The Laboratory Examination for Diabetes Mellitus

1
The Laboratory Examination for
Diabetes Mellitus
2
What is diabetes mellitus?

• The majority of intake of food is converted into
  glucose.
• The pancreas produces the insulin hormone, which
  help the organism to take advantage of glucose.
• In persons with diabetes, the insulin does not
  work. Therefore, the sugar and the fat increase
  in the blood.

3
(No Transcript)
4
The World Wide EpidemicPrevalence of Diabetes
5
8
3
14
4
5
The Worldwide EpidemicDiabetes Trends
Sources www.who.int www.idf Zimmet P. et al
Nature 414, 13 Dec 2001
6
Types of Diabetes

• There are several types of diabetes
• Type I - body does not produce any insulin.
• Type II- body is not making enough or is losing
  sensitivity to insulin made.

7
Types of Diabetes

• Secondary - a consequence from another disease.
  For example, pancreatitis or cystic fibrosis.
• Gestational Diabetes- diabetes during pregnancy.
• Impaired Glucose Tolerance- an intermediate
  between normal and diabetes.

8
Type I

• Usually diagnosed in children and young adults.
• Must take daily insulin shots to stay alive.
  (insulin dependent)
• Type I accounts for 5-10 of the population with
  diabetes.

9
Type II

• adult on set diabetes non-insulin dependant
• The most common form of the disease.
• Approximately 50 of men and 70 of women are
  obese at the time of diagnosis.

10
Whos at risk of Type II?
11
Risk factors

• Family history of diabetes
• Older than 30 years of age
• Lack of physical activity
• Sedentarism ( person with little or no physical
  activity)
• Poor diet
• Excessive weight

12
Classification of Diabetes
13
What are the Symptoms?

• Polyphasia- excessive eating
• Polyurea- excessive urination
• Polydypsia-excessive fluid intake
• Blurred vision
• Poor wound healing
• Irritability

14
Complications

• Diabetic retinopathy a leading cause of
  blindness and visual disability
• Kidney failure
• Heart disease
• Diabetic neuropathy
• Diabetic foot disease

15
The Laboratory Examination

• Laboratory plays an important part in the
  diagnosis and care of diabetic patients

16
Glucose Oxidase

• GLU2H2OO2 GOD Gluconic acid 2H2O2
• 2H2O2 4-aminoantipyrine 1,7-dihy-droxynaphthalen
  e POD red dye

17
Reference Interval

• Fasting glucose 3.9 - 6.11mmol/l

• (fasting is defined as no calorie intake
  for at least 8 hours)

18
Old Diagnostic Criteria

• Beware
• Many books and ward handbooks contain out of date
  diagnostic criteria
• Always
• check that you are using the most up to date
  values.

19
WHO Diagnostic criteria 2000

• Symptoms of diabetes (ie polyuria, polydipsia and
  unexplained weight loss) plus
• a random plasma glucose concentration gt 11.1
  mmol/L or
• a fasting plasma glucose concentration gt 7.0
  mmol/L
• With no symptoms, diagnosis should not be based
  on a single plasma glucose determination. At
  least another plasma glucose on another day with
  a value in the diabetic range is essential.

20
Urine Tests

• URINE "GLUCOSE"
• lacks sensitivity positivity in disease
• poor specificity negativity in health
• Problems
• renal threshold variable 6 to 15 mmol/L
• interferences Clinitest / Glucose oxidase
  strips
• IF URINE TEST POSITIVE
• A CONFIRMATORY BLOOD TEST IS NEEDED

21
Blood Tests

• Glucose
• whole blood 10-15 lower than plasma
• venous 10 lower than capillary
• Venous blood - loss of 0.33 mmol/L per hour
• There is no decrease within 24 h in the presence
  of sodium fluoride

22
Oral Glucose Tolerance Test (OGTT)

• A venous blood sample will be collected for the
  determination of fasting glucose
• Load of 75g of glucose is ingested within 5 min
• Blood samples will be collected at timed
  intervals (30min, 60min, 120min) for the
  determination of glucose

23
OGTT Criteria

• Plasma glucose (mmol/L)
• 0 min 120 min
• Non diabetic lt 6.1 lt 7.8
• Impaired glucose tolerance 6.1 - 6.9 gt7.8 - 11.1
• Diabetic gt 7.0 gt 11.1

24
Impaired Glucose Tolerance

• Higher than normal plasma glucose but lower than
  the diagnostic values for DM
• Precursor for Type II
• Only about 25 develop into type II and rest go
  back to normal
• Patients are more susceptible to macrovascular
  diseases.

25
Glycosylated proteins

• Caused by non-enzymatic glycosylation
• Glycosylated hemoglobin
• HbA1c - LGI ref range 4.6-6.5
• indicates previous 2-3 months glycaemic exposure
• n.b. affetced by altered red cell survival
• Fructosamine
• mirrors glycosylation of all serum proteins
• indicates previous 2-3 weeks glycaemic exposure
• used pregnancy/children in some sites
• Glycosylated albumin
• indicates previous several days glycaemic
  exposure
• not commonly used

26
Hemoglobin A1c

• HbA1c is stable glycosylated hemoglobin
• Its percentage concentration indicates cumulative
  glucose exposure

27
Hemoglobin A1c

• A good indicator of blood glucose control.
• Gives a that indicates control over the
  preceding 2-3 months.
• Performed 2 times a year.
• A hemoglobin of 6 indicates good control and
  level gt8 indicates action is needed.

Lowering HbA1C Reduces Risk of Complications
28
Diabetes is preventable by life style modification

• Maintain a healthy body weight
• Half an hour of exercise daily
• Eat a healthy diet

(fruits, vegetables, bread, milk)
29
Conclusion
In Conclusion

• Diabetes is a very complicated disease. It is
  easy to diagnosis and it is difficult to treat
• Laboratory plays an important part in the
  diagnosis and care of diabetic patients

30
THE END