How is diabetes diagnosed?
Diabetes is diagnosed with fasting sugar blood tests or with A1c blood tests, also known as glycated hemoglobin tests. A fasting blood sugar test is performed after you have had nothing to eat or drink for at least eight hours. Normal fasting blood sugar is less than 100 mg/dl (5.6 mmol/l). You do not have to be fasting for an A1c blood test. Diabetes is diagnosed by one of the following (see chart):
- Your blood sugar level is equal to or greater than 126 mg/dl (7 mmol/l).
- You have two random blood sugar tests over 200 mg/dl (11.1 mmol/l) with symptoms.
- You have an oral glucose tolerance test with results over 200 mg/dl (11.1 mmol/l).
- Your A1c test is greater than 6.5% on two separate days.
An A1c test should be performed in a laboratory using a method that is certified by the National Glycohemoglobin Standardization Program (NGSP) and standardized to the Diabetes Control and Complications Trial (DCCT) assay.
- Fasting Glucose Test
- Normal: Less than 100
- Pre-diabetes: 100-125
- Diabetes: 126 or higher
- Random (anytime) Glucose Test
- Normal: Less than 140
- Pre-diabetes: 140-199
- Diabetes: 200 or higher
- A1c Test
- Normal: Less than 5.7%
- Pre-diabetes: 5.7 - 6.4%
- Diabetes: 6.5% or higher