Screening for Diabetes

What are the tests used to screen and diagnose diabetes?

1.  Fasting Blood Sugar Test

A venous blood sample is taken after an overnight fast. The normal fasting blood glucose level is between 70-99 mg/dl (3.9 –5.5mmol/L). You are diagnosed with Diabetes if the level exceeds 126 mg/dl (7mmol/L) on two separate tests.

2.  HbA1C (Glycated Haemoglobin) Test

HbA1C measures the average blood glucose level for the past two to three months. It works by measuring the percentage of blood glucose attached to the Haemoglobin which is the oxygen carrying protein in the red blood cells.

More Haemoglobin will have the blood glucose attached if the blood glucose level rises.

You are diagnosed to have Diabetes if the HbA1C level exceeds 6.5% on two separate tests.

3.  Oral Glucose Tolerance Test (OGTT)

You are asked to fast overnight for at least 8 hours for this test. A sample of the blood is taken before you are asked to drink a concentrated sugar solution. Your blood glucose level is then measured again after two hours. The following conclusion can be drawn based on the result of the OGTT:

• Normal : Blood glucose less than 140 mg/dl (7.8mmol/L)
• Pre-diabetes (also known as impaired OGTT) : Blood glucose level from 140-199 mgldl (7.8 to 11mmol/L)
• Diabetes : Blood glucose level exceeds 200 mg/dl (11.1mmol/L)