Title: Definition:
1Definition
Diabetes Mellitus
- Diabetes mellitus (DM) is a syndrome of chronic
hyperglycemia due to relative insulin deficiency,
resistance, or both. - Epidemiology
- The prevalence of diabetes for all age groups
worldwide was estimated to be 2.8 in 2000 and to
increase to 4.4 in 2030. - At diagnosis, 50 of patients have micro-vascular
complications (diabetic neuropathy, nephropathy,
or retinopathy). - The risk of macro-vascular complications is at
least two times higher than that of the general
population.
- The risk of developing diabetes increases with
age, obesity, and lack of physical activity. - Type 2 diabetes is more common in individuals
with a family history of the disease. - It is more common in women with prior history of
gestational diabetes and polycystic ovarian
syndrome and in individuals with hypertension,
dyslipidemia or impaired glucose tolerance.
Insulin structure and secretion
- Insulin is the key hormone involved in the
storage and controlled release within the body of
the chemical energy available from food. - It is coded for on chromosome 11 and synthesized
in the beta-cells of the pancreatic islets as a
polypeptide hormone. - After secretion, insulin enters the portal
circulation and is carried to the liver, its
prime target organ. About 50 of secreted insulin
is extracted and degraded in the liver the
residue is broken down by the kidneys. C-peptide
is only partially extracted by the liver (and
hence provides a useful index of the rate of
insulin secretion).
- glucose metabolism
- Blood glucose levels are closely regulated in
health within the range of 3.5-8.0 mmol/L (63-144
mg/dL), despite the varying demands of food,
fasting and exercise. - The principal organ of glucose homeostasis is the
liver, which absorbs and stores glucose (as
glycogen) in the post-absorptive state and
releases it into the circulation between meals to
match the rate of glucose utilization by
peripheral tissues. - The liver by the process of gluconeogenesis can
form new glucose from end metabolites of fat ,
protein, and lactic acid. - Glucose production
- About 200 g of glucose is produced and utilized
each day. More than 90 is derived from liver
glycogen and hepatic guconeogenesis, and the
remainder from renal gluconeogenesis.
- Glucose utilization
- The brain is the major consumer of glucose. Its
requirement is 1 mg/kg bodyweight per minute, or
100 g daily in a 70 kg man. - Glucose uptake by the brain is obligatory and is
not dependent on insulin, and the glucose used is
oxidized to carbon dioxide and water. - Other tissues, such as muscle and fat, are
facultative glucose consumers. - Glucose taken up by muscle is stored as glycogen
or broken down to lactate, which re-enters the
circulation and becomes a major substrate for
hepatic gluconeogenesis. But the main source of
muscle energy is derived from fatty-acid
oxidation. - Fat tissue used glucose as a source of energy and
as a substrate for triglyceride synthesis
lipolysis releases fatty acids from triglyceride
together with glycerol, another substrate for
hepatic gluconeogenesis.
2Principal actions of insulin
- Rapid (seconds)
- Increased transport of glucose, amino acids, and
K into insulin-sensitive cells - Intermediate (minutes)
- Stimulation of protein synthesis Inhibition of
protein degradation - Activation of glycolytic enzymes and glycogen
synthetase - Inhibition of phosphorylase and gluconeogenic
enzymes - Delayed (hours)
- Increase in mRNAs for lipogenic and other enzymes
- Hormonal regulation
- Insulin actions in the fasting and postprandial
states differ . In the fasting state its main
action is to regulate glucose release by the
liver, and in the postprandial state it
additionally facilitates glucose uptake by fat
and muscle. - The effect of counter-regulatory hormones
(glucagon, epinephrine (adrenaline), cortisol and
growth hormone) is to cause greater production of
glucose from the liver and less utilization of
glucose in fat and muscle for a given level of
insulin.
- Glucose transport
- Cell membranes are not inherently permeable to
glucose. - A family of specialized glucose-transporter
(GLUT) proteins carry glucose through the
membrane into cells. - These are glycoproteins, coded for on the short
arm of chromosome 19. - GLUT-1 - enables basal non-insulin-stimulated
glucose uptake into many cells - GLUT-2 - transports glucose into the beta-cell a
prerequisite for glucose sensing. - GLUT-3 - enables non-insulin-mediated glucose
uptake into brain neurones and placenta. - GLUT-4 - enables much of the peripheral action of
insulin. It is the channel through which glucose
is taken up into muscle and adipose tissue cells
following stimulation of the insulin receptor .
Classification of DM
- DM is classified on the basis of the pathogenic
process that leads to hyperglycemia. - The two broad categories of DM are designated
- Type 1 (insulin-dependent diabetes mellitus)
- Type 2 (non-insulin-dependent diabetes mellitus)
- Type 1 diabetes is the result of complete or
near-total insulin deficiency. - Type 2 DM is a heterogeneous group of disorders
characterized by variable degrees of insulin
resistance, impaired insulin secretion, and
increased glucose production. - Type 2 DM is preceded by a period of abnormal
glucose homeostasis classified as impaired
fasting glucose (IFG) or impaired glucose
tolerance (IGT).
3Type 1 (insulin-dependent diabetes mellitus)
Secondary diabetes
- Although secondary diabetes accounts for only
1-2 of all new cases at presentation, it should
not be missed because the cause can often be
treated - Causes of secondary diabetes
- Pancreatic disease
- Cystic fibrosis
- Chronic pancreatitis
- Malnutrition-related pancreatic disease
- Pancreatectomy
- Hereditary haemochromatosis
- Carcinoma of the pancreas
- Endocrine disease
- Cushing's syndrome
- Acromegaly
- Thyrotoxicosis
- Phaeochromocytoma
- Glucagonoma
- Drug-induced disease
- Thiazide diuretics
- Corticosteroid therapy
- Insulin-receptor abnormalities
- Congenital lipodystrophy
- Acanthosis nigricans
- Genetic syndromes
- Friedreich's ataxia
- Dystrophia myotonica
- Causes
- Type 1 diabetes belongs to a family of
HLA-associated immune-mediated organ-specific
diseases. - Autoantibodies directed against pancreatic islet
constituents appear in the circulation within the
first few years of life, prior to the clinical
onset by many years , and also detected in cases
of late onset auto- immune DM(LADA). - Genetic susceptibility Type 1 diabetes is not
genetically predetermined, but increased
susceptibility to the disease may be inherited
(polygenic).
- Inheritance
- The identical twin of a patient with type 1
diabetes has a 30-50 chance of developing the
disease, indicating that additional modifying
factors are likely involved in determining
whether diabetes develops. - Children of people with type 1 diabetes have an
increased chance of developing type 1 diabetes.
by age 20 with a diabetic father the risk is
(3-7),and with a diabetic mother is (2-3). - If one child in a family has type 1 diabetes,
each sibling has a 6 risk of developing
diabetes by age 20. - If siblings are HLA-identical (share the same
HLA type as the affected child), the risk rises
to about 20.
4Environmental Factors
- Numerous environmental events have been proposed
to trigger the autoimmune process in genetically
susceptible individuals however, none have been
conclusively linked to diabetes. Identification
of an environmental trigger has been difficult
because the event may precede the onset of DM by
several years. - Putative environmental triggers include viruses
(coxsackie and rubella most prominently), bovine
milk proteins, and nitrosourea compounds.
Prevention of Type 1 DM
- A number of interventions have successfully
delayed or prevented diabetes in animal models. - Though results in animal models are promising,
these interventions have not been successful in
preventing type 1 DM in humans. The Diabetes
Prevention Trialtype 1 concluded that
administering insulin (IV or PO) to individuals
at high risk for developing type 1 DM did not
prevent type 1 DM. - In patients with new-onset type 1 diabetes,
treatment with anti-CD3 monoclonal antibodies has
recently been shown to slow the decline in
C-peptide levels.
Type 2 (non-insulin-dependent diabetes
mellitus)
- Pathogenesis
- Hyperglycemia in type 2 diabetes likely results
from complex genetic interactions, the expression
of which modified by environmental factors such
as body weight and exercise. - Genetic factors
- type 2 diabetes shows a clear familial
aggregation but does not inherited in a classic
mendelian fashion.
- 2- Insulin resistance
- Type 2 diabetes is heterogeneous , both of the
major pathogenic mechanisms i.e , impaired
insulin secretion and impaired insulin
action(insulin resistance or decreased insulin
sensitivity)are operative in variable degrees in
most patients. - The mechanism of insulin resistance remains
poorly understood there is a defect in insulin
receptor, defects in more distal (post- receptor)
pathways play a far greater role in insulin
resistance . - One important aspect of resistance is a reduced
capacity for translocation of GLUT4 to cell
surface in muscle cells, a separate defect in
glycogen synthesis is also likely to be present
and a variety of genetic abnormality in cellular
transduction of the insulin signal. - Hyperglycamia per se impairs the ß cell response
to glucose and promotes insulin resistance.
- Abnormalities of insulin secretion manifest early
in the course of type 2 diabetes. Normal subjects
have a biphasic insulin response to intravenous
glucose, but the first-phase insulin response is
lost as hyperglycaemia develops, and insulin
secretion in response to oral glucose is delayed
and exaggerated.
5CLINICAL PRESENTATION OF DIABETES
- Overview and prevention
- Whether an individual develops type 2 diabetes or
not is largely due to genetic factors. - When a person develops diabetes depends on
lifestyle - Clinical trials have shown that diet, exercise or
agents such as metformin have a marked effect in
delaying the onset of type 2 diabetes.
- Acute presentation
- Young people often present with a 2- to 6-week
history and report the classic triad of symptoms - polyuria - due to the osmotic diuresis that
results when blood glucose levels exceed the
renal threshold - thirst - due to the resulting loss of fluid and
electrolytes. - weight loss - due to fluid depletion and the
accelerated breakdown of fat and muscle secondary
to insulin deficiency. - Ketonuria is often present in young people(type
1) and may progress to ketoacidosis if these
early symptoms are not recognized and treated.
- Subacute presentation
- The clinical onset may be over several months or
years, particularly in older patients. Thirst,
polyuria and weight loss are typically present
but patients may complain of such symptoms as
easy fatigability , visual blurring (owing to
glucose-induced changes in refraction), or
pruritus vulvae or balanitis that is due to
Candida infection. - Complications as the presenting feature
- These include
- staphylococcal skin infections
- retinopathy noted during a visit to the optician
- a polyneuropathy causing tingling and numbness in
the feet - erectile dysfunction
- arterial disease, resulting in myocardial
infarction or peripheral gangrene.
- Asymptomatic diabetes
- Glycosuria or a hyperglycemia may be detected on
routine examination (e.g. for insurance purposes)
in individuals who have no symptoms of
ill-health. - Glycosuria is not diagnostic of diabetes but
indicates the need for further investigations. - NB renal glycosuria is an inherited low renal
threshold for glucose, transmitted either as a
Mendelian dominant or recessive trait , with an
incidence of about 1. - Physical examination at diagnosis
- Evidence of weight loss and dehydration may be
present, and the breath may smell of ketones. - Older patients may present with established
complications, and the presence of the
characteristic retinopathy is diagnostic of
diabetes.
6Diagnosis
The spectrum of diabetes a comparison of type 1 and type 2 diabetes mellitus The spectrum of diabetes a comparison of type 1 and type 2 diabetes mellitus The spectrum of diabetes a comparison of type 1 and type 2 diabetes mellitus
Type 1 (insulin dependent) Type 2 (non-insulin dependent)
Epidemiology Younger (usually lt 30 years of age) Older (usually gt 30 years of age)
Usually lean Often overweight
Increased in those of Northern European ancestry All racial groups. Increased in peoples of Asian, African, Polynesian and American-Indian ancestry
Seasonal incidence
Heredity HLA-DR3 or DR4 in gt 90 No HLA links
30-50 concordance in identical twins 50 concordance in identical twins
Pathogenesis Autoimmune disease No immune disturbance
Islet cell autoantibodies Insulin resistance
Insulitis
Association with other autoimmune diseases
Immunosuppression after diagnosis delays beta-cell destruction
Clinical Insulin deficiency Partial insulin deficiency
May develop ketoacidosis May develop hyperosmolar state
Always need insulin Many come to need insulin when beta-cells fail over time
Biochemical Eventual disappearance of C-peptide C-peptide persists
- The National Diabetes Data Group and World Health
Organization have issued diagnostic criteria for
DM based on the following parameters (1) the
spectrum of fasting plasma glucose (FPG) and the
response to an oral glucose load (OGTToral
glucose tolerance test) varies among normal
individuals, and (2) DM is defined as the level
of glycemia at which diabetes-specific
complications occur rather than on deviations
from a population-based mean. For example, the
prevalence of retinopathy in Native Americans
(Pima Indian population) begins to increase at a
FPG gt 6.4 mmol/L (116 mg/dL).
7Criteria for the Diagnosis of Diabetes Mellitus
- Symptoms of diabetes plus random blood glucose
concentration 11.1 mmol/L (200 mg/dL) or - Fasting plasma glucose 7.0 mmol/L (126 mg/dL)or
- Two-hour plasma glucose 11.1 mmol/L (200 mg/dL)
during an oral glucose tolerance test. - NB The glucose tolerance test is only required
for borderline cases and for diagnosis of
gestational diabetes.
The glucose tolerance test - WHO criteria
Adult 75 g glucose in 300 mL water. Child 1.75
g glucose/kg bodyweight. Only a fasting and a
120-min sample are needed. Results are for
venous plasma - whole blood values are lower. NB
FPG 5.66.9 mmol/L (100125 mg/dL) is defined
as IFG
Normal Impaired glucose tolerance Diabetes mellitus
Fasting Less than 7.0 mmol/L Less than 7.0 mmol/L More than 7.0 mmol/L (126mg/dL)
2 h after glucose Less than 7.8 mmol/L(140mg/dL) Between 7.8 and 11.0 mmol/L(140 and 199 mg/dL) 11.1 mmol/L or more (200mg/dL)
- Some investigators have advocated the hemoglobin
A1C (A1C) as a diagnostic test for DM. Though
there is a strong correlation between elevations
in the plasma glucose and the A1C, the
relationship between the FPG and the A1C in
individuals with normal glucose tolerance or mild
glucose intolerance is less clear, and thus the
use of the A1C is not currently recommended to
diagnose diabetes. - The diagnosis of DM has profound implications for
an individual from both a medical and financial
standpoint. Thus, these diagnostic criteria must
be satisfied before assigning the diagnosis of
DM. Abnormalities on screening tests for diabetes
should be repeated before making a definitive
diagnosis of DM, unless acute metabolic
derangements or a markedly elevated plasma
glucose are present . - The revised criteria also allow for the diagnosis
of DM to be withdrawn in situations where the FPG
reverts to normal.
TREATMENT OF DIABETES
- Goals of management
- Reduce acute and chronic complications.
- Improve quality of life.
- Prevent premature diabetes-related death.
- Maintain hemoglobin A1c less than 7.
- Clinical Standers
- FBG 100-120 mg\dl
- PPBG 140-160 mg\dl
- Bedtime BG 100-140mg\dl
8- The role of patient education and community care
- The care of diabetes is based on self-management
by the patient, who is helped and advised by
those with specialized knowledge , as whatever
the technical expertise applied, the outcome
depends on willing cooperation by the patient. - The best time to educate the patient is soon
after diagnosis. Organized education programmes
will involve all healthcare workers, including
nurse specialists, dietitians and podiatrist. - Lifestyle modifications
- Weight loss
- Exercise
- Dietary management
Nutritional Recommendations for Adults with
Diabetes
- Fat
- 2035 of total caloric intake
- Saturated fat lt 7 of total calories
- Two or more servings of fish/week provide -3
polyunsaturated fatty acids - Carbohydrate
- 4565 of total caloric intake (low-carbohydrate
diets are not recommended) . - Amount and type of carbohydrate important
- Sucrose-containing foods may be consumed with
adjustments in insulin dose
- Protein
- 1035 of total caloric intake (high-protein
diets are not recommended) i.e 1.0 to 1.5 g\kg
per day, to be restricted in nephropathy 0.8 g\kg
per day. - Other components
- Fiber-containing foods may reduce postprandial
glucose peak - Non-nutrient sweeteners
- Exercise
- Exercise has multiple positive benefits including
- cardiovascular risk reduction,
- reduced blood pressure,
- maintenance of muscle mass
- reduction in body fat
- weight loss and lowering plasma glucose (during
and following exercise) and increasing insulin
sensitivity.
- In patients with diabetes, it is recommended to
be150 min/week (distributed over at least 3 days)
of aerobic physical activity. - In patients with type 2 DM, the exercise regimen
should also include resistance training. - Pharmacotherapy
- Oral Hypoglycemic agents
- Sulphonylureas
- Their principal action is to promote insulin
secretion in response to glucose - Minor extra panceatic role as insulin sensitizers.
9Properties of the most commonly used sulphonylureas Properties of the most commonly used sulphonylureas
Drug Features
Tolbutamide Lower maximal efficacy than other sulphonylureas
Short half-life - preferable in elderly
Largely metabolized by liver - can use in renal impairment
Glibenclamide, glipizide and glimepiride Long biological half-lifeActive metabolitesRenal excretion - avoid in renal impairment
Gliclazide Fairly long biological half-life
Largely metabolized by liver - can use in renal impairment
More costly
Properties of the most commonly used
sulphonylureas (cont.)
Drug Features
Chlorpropamide Very long biological half-life
Renal excretion - avoid in renal impairment
1-2 develop inappropriate ADH-like syndrome
Facial flush with alcohol
Very inexpensive - major issue for developing countries
Drug interactions and side-effects
- Sulphonylureas should be used with care in
patients with liver disease, and only those
primarily excreted by the liver should be given
to patients with renal impairment. (Tolbutamide
,Gliclazide) - All encourage weight gain and are therefore not
drugs of first choice in obese patients. - Tolbutamide is the safest drug in the very
elderly because of its short duration of action. - Hypoglycaemia is the most common and dangerous
side-effect. Specially in long acting type eg,
Chlorpropamide - Skin rashes and other sensitivity reactions do
rarely occur. - All sulphonylureas bind to circulating albumin
and may be displaced by other drugs, such as
sulphonamides, that compete for their binding
sites ,also interact with warfarin.
10Biguanides
- Metformin is currently the best validated primary
treatment for type 2 diabetes. - Mechanism of action
- It remains unclear but it reduces
gluconeogenesis, thus suppressing hepatic glucose
output, and it increases insulin sensitivity. - Unlike the sulphonylureas it does not induce
hypoglycaemia in normal volunteers. - It is particularly helpful in the overweight
since it does not promote weight gain. - It may be given in combination with
sulphonylureas or thiazolidinediones. - Side-effects
- Anorexia, epigastric discomfort and diarrhoea.
- Lactic acidosis has occurred in patients with
severe hepatic or renal disease, and metformin is
contraindicated when these are present. - Most diabetologists withdraw the drug when serum
creatinine exceeds 1.5 in males and 1.4 in
females.
Thiazolidinediones
- The thiazolidinediones (more conveniently known
as the 'glitazones') reduce insulin resistance by
interaction with peroxisome proliferator-activated
receptor-gamma (PPAR-gamma), a nuclear receptor
which regulates genes involved in lipid
metabolism and insulin action. - One suggestion is that they act indirectly via
the glucose-fatty acid cycle, lowering free fatty
acid levels and thus promoting glucose
consumption by muscle. - They can be used alone or in combination with
other agents. - The glitazones reduce hepatic glucose production,
an effect that is synergistic with that of
metformin, and also enhance peripheral glucose
uptake thus, potentiate the effect of endogenous
insulin.
- Side effects
- Contraindicated in mild liver impairment(
elevated serum trasaminases 2.5 times the upper
limit ofnormal). - Given cautiously to patient with heart failure ,
renal impairment. - Fluid retention , mild oedema and weight gain.
- a-Glucosidase Inhibitors
- -Glucosidase inhibitors (acarbose and miglitol)
reduce postprandial hyperglycemia by delaying
glucose absorption they do not affect glucose
utilization or insulin secretion . - These drugs, taken just before each meal, reduce
glucose absorption by inhibiting the enzyme that
cleaves oligosaccharides into simple sugars in
the intestinal lumen.
- Side effects
- GIT disturbance flatulence , abdominal
distension . - Contraindicated in hepatic impairment.
- Meglitinides
- Repaglinide and nateglinide are non-sulphonylurea
insulin secretagogues known as the meglitinides. - Advantages
- Low incideace of hypoglycaemia as they are
short-acting agents that promote insulin
secretion in response to meals . - Disadvantages
- They are more expensive than standard
sulphonylureas.
11Insulin treatment
- Indications
- Type 1 (insulin-dependent diabetes mellitus)
- Gestational diabetes
- Diabetic ketoacidosis, hyperosmolar diabetic coma
- Hyperglycemia despite maximum doses of oral
agents - Surgical procedures
- Infection, acute injury, stress
- Allergy or other serious reaction to oral agents
- Insulin delivery methods
- Syringes
- Pens
- Insulin pump
- Inhalation
Pharmacokinetics of Insulin Preparations
Time of Action Time of Action Time of Action
Preparation Onset, h Peak, h Effective Duration, h
Short-acting, subcutaneous
Lispro lt0.25 0.51.5 34
Aspart lt0.25 0.51.5 34
Glulisine lt0.25 0.51.5 34
Regular 0.51.0 23 46
Short-acting, inhaled
Inhaled regular insulin lt0.25 0.51.5 46
Preparation Onset, h Peak, h Effective Duration, h
Long-acting
NPH 14 610 1016
Detemir 14 1220
Glargine 14 24
Insulin Combinations
75/2575 protamine lispro, 25 lispro lt0.25 1.5 h Up to 1016
70/3070 protamine aspart, 30 aspart lt0.25 1.5 h Up to 1016
50/5050 protamine lispro, 50 lispro lt0.25 1.5 h Up to 1016
70/3070 NPH, 30 regular insulin 0.51 Dual 1016
50/5050 NPH, 50 regular insulin 0.51 Dual 1016
12Insulin administration patterns
- 1-Conventional One or two injections per day of
intermediate acting such as zinc insulin
(lente)or isophane(NPH) with or without the
addition of small amount of regular insulin.
Usual starting dose is 20 u\day. - Premixed preparations may be used as two thirds
of the dose before breakfast and one third before
dinner. - 2- Multiple S.C insulin injections intermediate
, long acting or basal insulin single bedtime
dose with regular insulin prior to each meal. - 3- Continuous S.C insulin infusion insulin pump
Guide to adjusting insulin dosage according to blood glucose test results Guide to adjusting insulin dosage according to blood glucose test results Guide to adjusting insulin dosage according to blood glucose test results
Blood glucose persistently too high Blood glucose persistently too low
Before breakfast Increase evening long-acting insulin Reduce evening long-acting insulin
Before lunch Increase morning short-acting insulin Reduce morning short-acting insulin or increase mid-morning snack
Before evening meal Increase morning long-acting insulin or lunch short-acting insulin Reduce morning long-acting insulin or lunch short-acting insulin or increase mid-afternoon snack
Before bed Increase evening short-acting insulin Reduce evening short-acting insulin
Complications of insulin therapy
- At the injection site
- Shallow injections result in intradermal insulin
delivery and painful, reddened lesions or even
scarring. - Injection site abscesses occur but are extremely
rare. - Local allergic responses sometimes occur early in
therapy but usually resolve spontaneously. - Generalized allergic responses are exceptionally
rare. - Fatty lumps, known as lipohypertrophy, may occur
as the result of overuse of a single injection
site with any type of insulin. - Systemic complications
- Insulin resistance
- Hypoglycemia
- Weight gain ,especially if the insulin dose is
increased inappropriately.
Monitoring the Level of Glycemic Control
- Self-Monitoring of Blood Glucose (SMBG) The
frequency of SMBG measurements must be
individualized and adapted to address the goals
of diabetes care. Individuals with type 1 DM or
individuals with type 2 DM taking multiple
insulin injections each day should routinely
measure their plasma glucose three or more times
per day to estimate and select mealtime boluses
of short-acting insulin and to modify long-acting
insulin doses. Most individuals with type 2 DM
require less frequent monitoring, though the
optimal frequency of SMBG has not been clearly
defined. - Assessment of Long-Term Glycemic Control
- Glycated hemoglobin or A1C (standardized range
4-6.5) should be measured in all individuals
with DM during their initial evaluation and as
part of their comprehensive diabetes care. As the
primary predictor of long-term complications of
DM, the A1C should mirror, to a certain extent,
the short-term measurements of SMBG. - It ideally to kept lt 7.
13Acute Complications of DM
- Diabetic ketoacidosis
- Diabetic ketoacidosis (DKA) was formerly
considered a hallmark of type 1 DM, but it can
occur in obese individuals with type 2 DM with
absolute or relative insulin deficiency. - It is usually seen in the following
circumstances - previously undiagnosed diabetes
- interruption of insulin therapy
- the stress of intercurrent illness.
- Pathogenesis
- DKA results from relative or absolute insulin
deficiency combined with counter regulatory
hormone excess (glucagon, catecholamines,
cortisol, and growth hormone).
- This promotes gluconeogenesis, glycogenolysis,
and ketone body formation in the liver, as well
as increases in substrate delivery from fat and
muscle (free fatty acids, amino acids) to the
liver. - Rising glucose levels lead to an osmotic
diuresis, loss of fluid and electrolytes, and
dehydration. - Plasma osmolality rises and renal perfusion
falls. In parallel, rapid lipolysis occurs,
leading to elevated circulating free fatty-acid
levels. - Accumulation of ketone bodies produces a
metabolic acidosis. Vomiting leads to further
loss of fluid and electrolytes. - ketone bodies are excreted in the urine ,and also
appear in the breath, producing a distinctive
smell similar to that of acetone. - Respiratory compensation for the acidosis leads
to hyperventilation, 'air hunger'. - Progressive dehydration impairs renal excretion
of hydrogen ions and ketones, aggravating the
acidosis. - As the pH falls below 7.0 , pH-dependent enzyme
systems in many cells function less effectively. - Untreated, severe ketoacidosis is invariably
fatal.
- Clinical Features
- Symptoms of DKA are of gradual onset , may take
days . - Hyperglycemia Polyuria, nocturia, polydipsia ,
weight loss. - Dehdration dry skin and tongue, hypotension,
weak rapid pulse oliguria. - Acidosis(ketone bodies )Vomiting ,abdominal pain
, acetone odour in breath and Kussmaul breathing
. - Lethargy and central nervous system depression
may evolve into coma with severe DKA but should
also prompt evaluation for other reasons for
altered mental status (infection, hypoxia, etc.).
- Cerebral edema, an extremely serious complication
of DKA, is seen most frequently in children. - Signs of infection, which may precipitate DKA,
should be sought on physical examination, even in
the absence of fever. - Tissue ischemia (heart, brain) can also be a
precipitating factor.
14Management of Diabetic Ketoacidosis
- Confirm diagnosis (plasma glucose, positive serum
ketones, metabolic acidosis). - Admit to hospital intensive-care setting may be
necessary for frequent monitoring or if pH lt 7.00
or unconscious. - Assess
- Serum electrolytes (K, Na, Mg2, Cl-,
bicarbonate, phosphate) - Acid-base statuspH, HCO3-, PCO2,
ß-hydroxybutyrate - Renal function (creatinine, urine output)
- Replace fluids 23 L of 0.9 saline over first
13 h (1015 mL/kg per hour) subsequently, 0.45
saline at 150300 mL/h change to 5 glucose and
0.45 saline at 100200 mL/h when plasma glucose
reaches 250 mg/dL (14 mmol/L). - Administer short-acting insulin IV (0.1
units/kg) or IM (0.3 units/kg), then 0.1 units/kg
per hour by continuous IV infusion increase 2-
to 3-fold if no response by 24 h. If initial
serum potassium is lt 3.3 meq/L, do not administer
insulin until the potassium is corrected to gt 3.3
meq/L. - Assess patient What precipitated the episode
(noncompliance, infection, trauma, infarction)?
Initiate appropriate workup for precipitating
event (cultures, CXR, ECG).
- Measure capillary glucose every 12 h measure
electrolytes (especially K, bicarbonate,
phosphate) and anion gap every 4 h for first 24
h. - Monitor blood pressure, pulse, respirations,
mental status, fluid intake and output every 14
h. - Replace K 10 meq/h when plasma K lt 5.5 meq/L,
ECG normal, urine flow and normal creatinine
documented administer 4080 meq/h when plasma K
lt 3.5 meq/L or if bicarbonate is given. - Continue above until patient is stable, glucose
goal is 150250 mg/dL, and acidosis is resolved.
Insulin infusion may be decreased to 0.050.1
units/kg per hour. - Administer intermediate or long-acting insulin as
soon as patient is eating. Allow for overlap in
insulin infusion and subcutaneous insulin
injection.
Hyperglycemic Hyperosmolar Non-ketotic
state(HHNS)
- It is a metabolic emergency characteristic of
old uncontrolled type 2 diabetes. - Common precipitating factors include
- Consumption of glucose-rich fluids .
- Concurrent medication such as thiazide diuretics
or steroids. - Intercurrent illness.
- N.B Non-ketotic coma and ketoacidosis represent
two ends of a spectrum rather than two distinct
disorders
Pathogenesis
- Relative insulin deficiency and inadequate fluid
intake are the underlying causes of HHS. - Insulin deficiency increases hepatic glucose
production (through glycogenolysis and
gluconeogenesis) and impairs glucose utilization
in skeletal muscle . - Hyperglycemia induces an osmotic diuresis that
leads to intravascular volume depletion, which is
exacerbated by inadequate fluid replacement. - The absence of ketosis in HHS is not completely
understood. Presumably, the insulin deficiency is
only relative and less severe than in DKA, lower
levels of counter regulatory hormones and free
fatty acids, and also may be because that the
liver is less capable of ketone body synthesis or
that the insulin/glucagon ratio does not favor
ketogenesis.
15Clinical Features
- dehydration and stupor or coma Impairment of
consciousness is directly related to the degree
of hyperosmolality. - Evidence of underlying illness such as pneumonia
or pyelonephritis may be present. - The hyperosmolar state may predispose to stroke,
myocardial infarction or arterial insufficiency
in the lower limbs. - Laboratory Abnormalities and Diagnosis
- Sever hyperglycemia plasma glucose may be gt55.5
mmol/L (1000 mg/dL). - Hyperosmolality (gt350 mosmol/L).
- Prerenal azotemia.
- In contrast to DKA, acidosis and ketonemia are
absent or mild,but small anion gap metabolic
acidosis may be present secondary to increased
lactic acid. - Moderate ketonuria, if present, is secondary to
starvation.
- N.B
- The normal range of osmolality is 285-300
mOsm/kg. It can be measured directly, or can be
calculated approximately from the formula
Osmolality 2(Na K) glucose urea
(all in mmol/L). - The normal anion gap is less than 17. It is
calculated as (Na K) - (Cl- HCO3-). - Treatment
- Fluid replacement should initially stabilize the
hemodynamic status of the patient (13 L of 0.9
normal saline over the first 23 h). the rapidity
of reversal of the hyperosmolar state must
balance the need for free water repletion with
the risk that too rapid a reversal may worsen
neurologic function. - If the serum sodium gt 150 meq/L, 0.45 saline
should be used. After hemodynamic stability is
achieved, the IV fluid administration is directed
at reversing the free water deficit using
hypotonic fluids (0.45 saline initially then 5
dextrose in water, D5W).
- The calculated free water deficit (which averages
910 L) should be reversed over the next 12 days
(infusion rates of 200300 mL/h of hypotonic
solution)guided by CV line monitoring of the
volume status. - Insulin and K supplement are like DKA.
- Treatment of the underlying illness.
- Prognosis
- The reported mortality ranges as high as 20-30,
mainly because of the advanced age of the
patients and the frequency of intercurrent
illness.
Lactic acidosis
- Lactic acidosis may occur in diabetic patients on
biguanide therapy, if the therapeutic dose is
exceeded or the drug is not withheld in patients
with advanced hepatic or renal dysfunction. - Patients present in severe metabolic acidosis
with a large anion gap (normally less than 17
mmol/L), usually without significant
hyperglycaemia or ketosis. - Treatment
- Rehydration and infusion of isotonic 1.26
bicarbonate. - Prognosis
- The mortality is in excess of 50.
16Treatment
Hypoglycemia
- It occurs more common in type 1 DM especially
those on intensive insulin therapy, but it is
rare with the recent insulin analogues that have
no high beaks as old insulin formula. - Pathogenesis
- In normal subjects , fasting results in release
of adrenaline and glucagon to stimulate
glycogenolysis and gluconeogenesis .This hormone
release is blunted in type 1 DM . - NB
- If hypoglycemia occurs in type 2 DM on oral
hypoglycemic agents ,it is more prolonged ,more
sever ,so the pt should be hospitalized and
monitored for at least 24 h after resolution of
the attack.
- Predisposing factors
- Missed or small meal
- Over dose of insulin
- Unexpected increased activity.
- Clinical Features
- The most common symptoms and signs of
hypoglycaemia are neurological as the brain
consumes about 50 of the total glucose produced
by the liver these include cold sweating
,shaking, tachycardia, dilated pupils and
tremors.(release of adrenaline ) - If the condition is prolonged pt will develop
cognitive impairment, dizziness, hunger,
convulsions, coma without lateralizing signs and
bilateral extensor planter response ,and
irreversible brain damage death. (decrease
glucose supply to the brain which is the only
fuel)
Chronic Complications of DM
- If the pt is conscious a sugary fluid is given
and a meal is taken after 15 minutes - If the pt is unconscious IV glucose ( 25-50 ml
50) - Glucagon 1mg IM
- Searching for and correcting the predisposing
factors
- The chronic complications of DM affect many organ
systems and are responsible for the majority of
morbidity and mortality associated with the
disease these include - Microvascular complications
- Retinopathy,(non proliferative/proliferative),
macular edema - Neuropathy sensory and motor(mono- and
polyneuropathy), autonomic - Nephropathy
- Macrovascular complications
- Coronary artery disease
- Peripheral arterial disease
- Cerebrovascular disease
- Other complications
- Gastrointestinal (gastroparesis, diarrhea)
- Genitourinary (uropathy/sexual dysfunction)
- Dermatologic infectious
- Cataracts
- Glaucoma
- Periodontal disease
17Mechanisms of Complications
- Although chronic hyperglycemia is an important
etiologic factor leading to complications of DM,
the mechanism(s) by which it leads to such
diverse cellular and organ dysfunction is
unknown. - Four prominent theories, have been proposed to
explain how hyperglycemia might lead to the
chronic complications of DM. - One theory
- the increased intracellular glucose leads to the
formation of advanced glycosylation end products
(AGEs) via the nonenzymatic glycosylation of
intra- and extracellular proteins. AGEs have been
shown to cross-link proteins (e.g., collagen,
extracellular matrix proteins), accelerate
atherosclerosis, promote glomerular dysfunction,
reduce nitric oxide synthesis, induce endothelial
dysfunction, and alter extracellular matrix
composition and structure. - The serum level of AGEs correlates with the
level of glycemia, and these products accumulate
as glomerular filtration rate declines.
- A second theory
- It is based on the observation that hyperglycemia
increases glucose metabolism via the sorbitol
pathway by the enzyme aldose reductase. Increased
sorbitol concentration increases cellular
osmolality, generates reactive oxygen species,
and likely leads to other types of cellular
dysfunction. However, testing of this theory in
humans, using aldose reductase inhibitors, has
not demonstrated significant beneficial effects
on clinical endpoints of retinopathy, neuropathy,
or nephropathy. - A third hypothesis proposes that hyperglycemia
increases the formation of diacylglycerol leading
to activation of protein kinase C (PKC). Among
other actions, PKC alters the cellular membrane
,and plasma lipoproteins rendering them more
atherogenic. endothelial cells and neurons.
Inhibitors of PKC are being studied in clinical
trials.
- A fourth theory proposes that hyperglycemia
increases the flux through the hexosamine
pathway. The hexosamine pathway may alter
function by glycosylation of proteins such as
endothelial nitric oxide synthase or by changes
in gene expression of transforming growth factor
(TGF-) or plasminogen activator inhibitor-1
(PAI-1). - Growth factors as appear to play an important
role in DM-related complications, and their
production is increased by most of these proposed
pathways. Vascular endothelial growth factor A
(VEGF-A) is increased locally in diabetic
proliferative retinopathy. TGF- is increased in
diabetic nephropathy and stimulates basement
membrane production of collagen and fibronectin
by mesangial cells. Other growth factors, such as
platelet-derived growth factor, epidermal growth
factor, insulin-like growth factor I, growth
hormone, basic fibroblast growth factor, and even
insulin, have been suggested to play a role in
DM-related complications.
- A possible unifying mechanism is that
hyperglycemia leads to increased production of
reactive oxygen species or superoxide in the
mitochondria these compounds may activate all
four of the pathways described above. Although
hyperglycemia serves as the initial trigger for
complications of diabetes, it is still unknown
whether the same pathophysiologic processes are
operative in all complications or whether some
pathways predominate in certain organs.
Ophthalmologic Complications of Diabetes Mellitus
- DM is the leading cause of blindness between the
ages of 20 and 74 in the United
States,individuals with DM are 25 times more
likely to become legally blind than individuals
without DM. - Blindness is primarily the result of progressive
diabetic retinopathy and clinically significant
macular edema. - Diabetic retinopathy is classified into two
stages - Nonproliferative diabetic retinopathy usually
appears late in the first decade or early in the
second decade of the disease and is marked by
retinal vascular microaneurysms, blot
hemorrhages, and cotton wool spots. Alterations
in retinal blood flow, increased retinal vascular
permeability and abnormal retinal
microvasculature, all of which lead to retinal
ischemia. - Proliferative diabetic retinopathyThe
appearance of neovascularization in response to
retinal hypoxia is the hallmark of proliferative
diabetic retinopathy
18Diabetic nephropathy
- These newly formed vessels appear near the optic
nerve and/or macula and rupture easily, leading
to vitreous hemorrhage, fibrosis, and ultimately
retinal detachment. - Duration of DM and degree of glycemic control are
the best predictors of the development of
retinopathy hypertension is also a risk factor.
Non proliferative retinopathy is found in almost
all individuals who have had DM for gt20 years
(25 incidence with 5 years, and 80 incidence
with 15 years of type 1 DM). - Treatment
- Early detection and treatment Annual
ophthalmologic examinations should begin within
5years in type1 and at the time of disease
detection in type 2. - Optimization of glycemic control delays and slows
progression of non-proliferative retinopathy with
only little evidence in proliferative retinopathy
. - Aggressive control of hypertension.
- Retinal LASER photocoagulation if progressive
retinopathy threatens vision. - Surgical treatmentVitrectomy in vitreous
hemorrhage or to cut extensive fibrous bands
causing retinal detachments.
- It is the leading cause of ESRD worldwide and a
leading cause of DM-related morbidity and
mortality. - It is usually manifests 15-25 years after
diagnosis and affects 25-35 of patients
diagnosed under the age of 30 years. - Pathophysiology
- The earliest functional abnormality in the
diabetic kidney is renal hypertrophy associated
with a raised glomerular filtration rate. This is
related to poor glycaemic control. - As the kidney becomes damaged by diabetes, the
afferent arteriole becomes vasodilated to a
greater extent than the efferent glomerular
arteriole. This increases the intraglomerular
filtration pressure, leads to further damaging
the glomerular capillaries and increased shearing
forces locally which are thought to contribute to
mesangial cell hypertrophy and increased
secretion of extracellular mesangial matrix
material. This process eventually leads to
glomerular sclerosis.
- Albuminuria At first 'microalbuminuria' -
amounts of urinary albumin so small ,may be
tested for by radioimmunoassay or by using
special dipsticks. - It is a predictive marker of progression to
nephropathy in type 1 diabetes, and of increased
cardiovascular risk in type 2 diabetes. - progression to overt proteinuria (gt300 mg/d),
only 50 of individuals progress to
macroalbuminuria over the next 10 years. - Once macroalbuminuria is present, there is a
steady decline in GFR, and 50 of individuals
reach ESRD in 710 years. - Once macroalbuminuria develops, blood pressure
rises slightly and the pathologic changes are
likely irreversible. - NB Some individuals with type 1 or type 2 DM
have a decline in GFR in the absence of micro- or
macroalbuminuria and this is the basis for
assessing the GFR on an annual basis using serum
creatinine.
- Ischaemic lesions
- Arteriolar lesions, with hypertrophy and
hyalinization of the vessels, can occur in
patients with diabetes. The appearances are
similar to those of hypertensive disease and lead
to ischaemic damage to the kidneys. - Diagnosis
- 1-Urine albumin assay
- As the onset of diabetic nephropathy is often
silent screening of younger patients for
microalbuminuria has to be done routinely, since
there is evidence that meticulous glycaemic
control or early antihypertensive treatment at
this stage may delay the onset of frank
proteinuria. - Once proteinuria is present, other possible
causes for this should be considered ,also assay
should be done in absence of urinary tract
infection,DKA, and vigorous exercise.
19- 2- Serum urea , Creatinine , Creatinine
clearance. - 3-Abdominal ultrasound to exclude obstractive
nephropathy - 4- Fundus examination in almost all cases of
diabetic nephropathy ,diabetic retinopathy is
present. - Management
- Improved glycemic control reduces the rate at
which microalbuminuria appears and progresses in
type 1 and type 2 DM. However, once
macroalbuminuria exists, it is unclear whether
improved glycemic control will slow progression
of renal disease. During the phase of declining
renal function, insulin requirements may fall as
the kidney is a site of insulin degradation.
Furthermore, many glucose-lowering medications
(sulfonylureas and metformin) are contraindicated
in advanced renal insufficiency. - Aggressive treatment of blood pressure with a
target below 130/80 mmHg has been shown to slow
the rate of deterioration of renal failure
considerably. Angiotensin-converting enzyme
inhibitors or an angiotensin receptor II
antagonist are the drugs of choice.
- These drugs should also be used in normotensive
patients with persistent microalbuminuria as
reduction in albuminuria occurs with this
treatment. - Associated diabetic retinopathy tends to progress
rapidly, and frequent ophthalmic supervision is
essential. - Management of ESRD is made more difficult by the
fact that patients often have other complications
of diabetes such as blindness, autonomic
neuropathy or peripheral vascular disease.
Vascular shunts tend to calcify rapidly and hence
chronic ambulatory peritoneal dialysis may be
preferable to haemodialysis. - The failure rate of renal transplants is somewhat
higher than in non-diabetic patients. A segmental
pancreatic graft is sometimes performed at the
same time as a renal graft .
Diabetic neuropathy
- It occurs in 50 of individuals with
long-standing type 1 and type 2 DM. It may
manifest as polyneuropathy, mononeuropathy,
and/or autonomic neuropathy. - As with other complications of DM, the
development of neuropathy correlates with the
duration of diabetes and glycemic control. - Additional risk factors are
- BMI (the greater the BMI, the greater the risk
of neuropathy) and smoking. - The presence of cardiovascular disease,
hypertension ,and elevated triglycerides. - It is recommended to screen for distal symmetric
neuropathy beginning with the initial diagnosis
of diabetes and screen for autonomic neuropathy 5
years after diagnosis of type 1 DM and at the
time of diagnosis of type 2 DM. - All individuals with diabetes should then be
screened annually for both forms of neuropathy.
- Pathophysiology
- The earliest functional change in diabetic nerves
is delayed nerve conduction velocity the
earliest histological change is segmental
demyelination, caused by damage to Schwann cells. - In the early stages axons are preserved,
implying prospects of recovery, but at a later
stage irreversible axonal degeneration develops. - The following varieties of neuropathy occur
- symmetrical mainly sensory polyneuropathy
(distal) - acute painful neuropathy
- mononeuropathy and mononeuritis multiplex
- (a) cranial nerve lesions
- (b) isolated peripheral nerve lesions
- diabetic amyotrophy
- autonomic neuropathy.
20- Symmetrical mainly sensory polyneuropathy
- It is the most common form of diabetic
neuropathy. - It most frequently presents with distal sensory
loss (deep before superficial), but up to 50 of
patients do not have symptoms of neuropathy. - Hyperesthesia and paresthesia also may occur.
- As neuropathy progresses any combination of these
symptoms may develop including a sensation of
numbness, tingling, sharpness, or burning that
begins in the feet and spreads proximally. - Involvement of the hands is much less common and
results in a 'stocking and glove' sensory loss. - Complications include unrecognized trauma,
beginning as blistering due to an ill-fitting
shoe, and leading to ulceration.
- Diabetic polyradiculopathy is a syndrome
characterized by severe disabling pain in the
distribution of one or more nerve roots. - It may be accompanied by motor weakness.
- Intercostal or truncal radiculopathy causes pain
over the thorax or abdomen. Involvement of the
lumbar plexus or femoral nerve may cause severe
pain in the thigh or hip and may be associated
with muscle weakness in the hip flexors or
extensors (diabetic amyotrophy). - Fortunately, diabetic polyradiculopathies are
usually self-limited and resolve over 612
months. - Mononeuropathy (dysfunction of isolated cranial
or peripheral nerves) is less common than
polyneuropathy in DM and presents with pain and
motor weakness in the distribution of a single
nerve. - A vascular etiology has been suggested, but the
pathogenesis is unknown. - Involvement of the third cranial nerve is most
common and is heralded by diplopia. Sometimes
other cranial nerves IV, VI, or VII (Bell's
palsy) are affected. Peripheral mononeuropathies
or simultaneous involvement of more than one
nerve (mononeuropathy multiplex) may also occur.
- Acute painful neuropathy A diffuse, painful
neuropathy is less common. The patient describes
burning or crawling pains in the feet, shins and
anterior thighs. These symptoms are typically
worse at night, and pressure from bedclothes may
be intolerable. - It may present at diagnosis or develop after
sudden improvement in glycaemic control (e.g.
when insulin is started). It usually remits
spontaneously after 3-12 months if good control
is maintained. - A more chronic form, developing later in the
course of the disease, is sometimes resistant to
almost all forms of therapy. - Neurological assessment is difficult because of
the hyperaesthesia experienced by the patient.
- Autonomic neuropathy
- Asymptomatic autonomic disturbances can be
demonstrated on laboratory testing in many
patients, but symptomatic autonomic neuropathy is
rare. - It affects both the sympathetic and
parasympathetic nervous systems. - The cardiovascular system
- Vagal neuropathy results in tachycardia at rest
,loss of sinus arrhythmia,loss of cardiovascular
reflexes such as the Valsalva maneuver are
impaired , postural hypotension occurs owing to
loss of sympathetic tone to peripheral arterioles
, and warm foot with a bounding pulse as a result
of peripheral vasodilatation. - Gastrointestinal tract Vagal damage can lead to
- gastroparesis, often asymptomatic, but sometimes
leading to intractable vomiting. - Autonomic diarrhoea often occurs at night
accompanied by urgency and incontinence. - Diarrhoea and steatorrhoea may occur owing to
small bowel bacterial overgrowth treatment is
with antibiotics such as tetracycline. - Constipation is the most commen symptom, but
diarrhoea is the most distressing. - Urinary bladder involvement Loss of tone,
incomplete emptying, and stasis (predisposing to
infection) resulting in an atonic, painless,
distended bladder.
21- Male erectile dysfunction
- Erectile dysfunction in diabetes has many causes
including anxiety, depression, alcohol excess,
drugs, primary or secondary gonadal failure,
hypothyroidism, and inadequate vascular supply
owing to atheroma in pudendal arteries. - The history and examination should focus on these
possible causes. Blood is taken for LH, FSH,
testosterone, prolactin and thyroid function. - Skin and sweat glands
- Distal anhydrosis ,gustatory sweating
,compensatory truncal and facial sweating
- Treatment
- Treatment of diabetic neuropathy is less than
satisfactory - Improved glycemic control should be aggressively
done and will improve nerve conduction velocity,
but symptoms of diabetic neuropathy may not
necessarily improve. - Risk factors for neuropathy such as hypertension
and hypertriglyceridemia should be treated. - Chronic, painful diabetic neuropathy is difficult
to treat but may respond to antidepressants or
anticonvulsants . - Aldose reductase inhibitors do not offer
significant symptomatic relief. - Since the pain of acute diabetic neuropathy may
resolve over time, medications may be
discontinued as progressive neuronal damage from
DM occurs. - For gastroparisis agents with some efficacy
include dopamine agonists metoclopramide, and
domperidone before each meal. - Erythromycin interacts with the motilin receptor
and may promote gastric emptying. Treatment of
bacterial overgrowth with antibiotics is
sometimes useful . - Diabetic diarrhea in the absence of bacterial
overgrowth is treated symptomatically.
- Diabetic cystopathy should be treated with timed
voiding or self-catheterization, possibly with
the addition of bethanechol. - Drugs that inhibit type 5 phosphodiesterase are
effective for erectile dysfunction, but their
efficacy in individuals with DM is slightly lower
than in the nondiabetic population . - Sexual dysfunction in women may be improved with
use of vaginal lubricants, treatment of vaginal
infections, and systemic or local estrogen
replacement.