Glycosylated Haemoglobin Test;
HbA1c is a measurement to assess the level of your blood sugar over the past 120 days.An HbA1c reading of over 6.1% is suggestive of diabetes.
Oral Glucose Tolerance Test:
After fasting overnight, you are given water with 75 gm sugar ( in a water-sugar solution).Your blood glucose levels are tested over a 24-hour period.

In a diabetic person, blood glucose levels rise higher than normal and do not fall as
quickly.A normal blood glucose reading, two hours after drinking the solution, should be less than 130 mg/dl. All readings between zero to two hours should be less than
200 mh/dl.

In addition to these ,a random blood sugar reading can be taken any time.A reading
of above 140 mg/dl can be indicative of diabetes.