First specimens of urine and blood are taken on fasting level. Thereafter, the patient is asked to take his normal meals. Next test is carried out after 1 hour 45 minutes or two hours. Accuracy of this result is sometimes doubted, for the simple reason that patients generally do not follow a uniform pattern on diet. Variations in food will result in variable test results. Ideal fasting level (NORMAL) result should be between 80-120 mg/dl and result after two hours or 1 hour 45 minutes should between 120-140. even 140 mg is considered to be normal, W.H.O. studies further reveal that P.P. level is tolerable even upto 200 mg but any reading beyond this is a definite indication to confirm presence of diabetes.

Note: In certain cases, G.T.T. or P.P. tests may rule out presence of glucose in the blood but the urine test may show presence of glucose in the urine (especially when glucose level remains normal in the blood). In such a case (provided the tests are fully reliable and dependable) one should infer renal glycosuria. But before jumping to any final conclusion, it is necessary to ascertain and find out if-
i. The patient passes glucose in urine, in the first urine in the morning or
ii. Whether it was on fasting or whether.
iii. It was traced after taking meals
If during G.T.T. there is presence of sugar (glucose) only in the urine (but not in the blood), then it is indicative of low renal threshold, so to say, which points to diseased state of kidneys. Patients who pass sugar in urine during ‘fasting’ state only (but not in P.P.tests), there is no cause for any anxiety. But if sugar is passed after taking meals it is a sure and certain indication of a diabetic status. No firm opinion should ever be formed, merely on the basis of a single urine and /or blood test of the patient.