Criteria for Diagnosis of diabetes
Guidelines.
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Urine Sugar testing must not be used to diagnose diabetes. |
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True blood glucose should be estimated using enzymatic methods like the 'Glucose Oxidase Method'. |
Criteria for diagnosis of diabetes mellitus.
Fasting blood glucose. (defined as no calorie intake for at least 8 hrs)
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Fasting venous whole blood glucose of more than 110 mg %. |
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Fasting venous plasma blood glucose (FPG) of more than 126 mg /dl.(7.0 mmol/l) |
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Random blood glucose.
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Casual or Random venous whole blood glucose of more than 180 mg %.(Plasma blood glucose of = or more than 200 mg /dl or 11.1 mmol/l),confirmed on repeated testing, in a patient with characteristic sign and symptoms of diabetes including Polyuria, Polydipsia, and unexplained weight loss. |
or
Glucose Tolerance Test.
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Abnormal 'Glucose Tolerance Test'. i.e. 2-h post load glucose > or = 200 mg /dl (11.1 mmol/l) during an OGTT. The test should be performed as described by the WHO, using a glucose load containing the equivalent of 75-g anhydrous glucose dissolved in water. |
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The use of HBA1c is not recommended for diagnosis of diabetes mellitus. |
Oral Glucose Tolerance Test. (O.G.T.T)
Preparation of patient.
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The person to be tested must be on a normal diet for at least 48 to 72 hours prior to the test; this should contain at least 300 grams of carbohydrates per day, which is not a problem in those eating a traditional Indian diet. |
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The test should be carried out after fasting for 8-10 hours. |
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The person must rest throughout the test. |
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No smoking during test. |
Procedure.
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Blood is collected in fasting state, and then 75 grams of glucose is given orally, this may be diluted to avoid nausea and flavored with a little lime to make it more palatable, the glucose solution should be drunk with in 2-3 minutes. |
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Blood is collected 2 hours after glucose ingestion. |
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The results are interpreted according to the WHO. criteria. |
GLUCOSE CONCENTRATION (mg / 100ml)
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WHOLE BLOOD |
PLASMA VENOUS | |
VENOUS |
CAPILLARY | ||
DIABETES MELLITUS DIAGNOSTIC CRITERIA | |||
FASTING OR 2 HRS POST GLUCOSE LOAD (DURING AN OGTT AS PER WHO GUIDELINES)
OR SYMPTOMS OF DIABETES + CASUAL PLASMA GLUCOSE |
>/=110
>/=180
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>/=110
>/=200
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>/=126
>/=200 (11.1 mmol/l)
>/=200 (11.1 mmol/l)
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IMPAIRED GLUCOSE TOLERANCE- I.G.T | |||
FASTING (IF MEASURED) & 2 HRS POST GLUCOSE LOAD
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<110 >/=120 &<180
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<110 >/=140 &<200
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<126 >/=140 &<200
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IMPAIRED FASTING GLYCEMIA- I.F.G | |||
FASTING 2 HRS POST GLUCOSE LOAD (IF MEASURED) |
>/=100 & <110 <120
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>/=100 & <110 <140
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>/=100 & <126 <140
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Impaired Glucose Tolerance (I.G.T)
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Many patients in this category will go on to have diabetes; |
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Many I.G.T. patients show associated problems like hypertension, lipid disorders, high uric acid, obesity etc. which merit treatment; |
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I.G.T. is a risk factor for development of macro vascular disease. (angina, stroke, retinal damage, kidney failure) |
Impaired Fasting Glycemia.- I.F.G
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Impaired fasting glycemia is an entity which has been recently introduced to delineate persons in whom only the fasting blood glucose has been done, but who do not come in the normal or diabetic category. |
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It has been proposed that the diagnosis of diabetes can be made from a fasting blood glucose level only and that it may not be necessary to do a complete Glucose Tolerance Test. (G.T.T) |
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The general consensus is that whilst doing only the fasting blood glucose may be sufficient to pin point those with diabetes, it may be better to confirm this with a complete Glucose Tolerance Test. (G.T.T), if feasible. |
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A negative Glucose Tolerance Test. (G.T.T) result shows that the patient is not a Diabetic at the time of testing; it does not mean that he will never develop Diabetes; such persons must have an annual check up. |