International Diabetes Center > Disease Information > Diagnosing Diabetes

Diagnosing diabetes

Diabetes is diagnosed using blood tests that measure the glucose (sugar level) in the blood. Two tests are used.

• A fasting blood glucose test is conducted when a person has had nothing but water for at least eight hours
• A casual (random) blood glucose test can be conducted any time.

These tests show whether the blood glucose level is too high. If it is, a person is diagnosed with diabetes.

Diagnosis	Fasting test	Casual test
Diabetes	126 mg/dL or higher	200 mg/dL or higher and symptoms
Normal	Less than 100 mg/dL	Less than 140 mg/dL

Some people have blood glucose levels higher than normal, but not high enough to be diabetes. This is known as prediabetes. People with prediabetes are at risk for diabetes.

Gestational diabetes

Gestational diabetes is diagnosed using an oral glucose tolerance test. All pregnant women without diabetes need to take this test. If two of the tests are higher than the values shown in the table below, a woman has gestational diabetes.

Test time	Plasma blood glucose
Fasting (before drinking a glucose solution)	95 mg/dL or higher
One hour after drinking a glucose solution	180 mg/dL or higher
Two hours after drinking a glucose solution	155 mg/dL or higher
Three hours after drinking a glucose solution	140 mg/dL or higher

To make an appointment with International Diabetes Center, call 952-993-3393 or toll-free at 888-825-6315.