Diagnosing Diabetes

Only your healthcare provider can tell if you have diabetes. Your provider may do one or more of the following tests to confirm:

 Tests
 Results
 Blood Glucose tested anytime of the day
(including those tested after meals)
 200 mg/dL (or 11.1 mmol/L) or more and you have symptoms of diabetes.
 FPG
Fasting Plasma Glucose
(no food at least for 8 hrs)
 126 mg/dL (7.0 mmol/L) or more on two occasions
 OGTT
2-hours Oral Glucose Tolerance Test
(Glucose level 2 hours after drinking a bottle of water containing 75 g of glucose)
 200 mg/dL (11.1 mmol/L) or more
A1C
Blood test that measures average blood glucose levels that were attached to red blood cells over the past 2-3 months. No fasting needed.
6.5% or more
 
All of the above tests need to be repeated to confirm if you have diabetes. The A1C test is recently approved to be used as diagnosis of type 2 diabetes. The oral glucose tolerance test (OGTT) may be a better test to determine if an individual of Asian descent has diabetes or pre-diabetes because the fasting plasma glucose test sometimes can miss the diagnosis especially in this population.

Diagnosing Pre-Diabetes

If your blood glucose is higher than normal but not high enough to be diagnosed as diabetes, you may have "pre-diabetes." Test results that could indicate pre-diabetes are as follows:
  • FPG   between  100-125 mg/dL or 5.6 – 6.9 mmol/L
  • OGTT between  140 - 199 mg/dL or 7.8 - 11.0 mmol/L
  • A1C   between   5.7% -6.4%