Healthy adults age 45 and older should get tested for diabetes every 3 years. Patients who have certain risk factors should ask their doctors about testing at an earlier age and more frequently. These risk factors include:
- A weight that is 20% more than ideal body weight
- Sedentary lifestyle
- High blood pressure (greater than 140/90) or unhealthy cholesterol levels -- especially for patients with low HDL ("good") cholesterol and high triglyceride levels
- History of heart disease, stroke, or peripheral artery disease
- A close relative (parent, sibling) with diabetes
- A high-risk ethnic group background (African-American, Latino, Native American, Asian American, Pacific Islander)
- Having delivered a baby weighing over 9 pounds or having a history of gestational diabetes (in women)
- Polycystic ovary disease (in women)
Children age 10 and older should be tested for type 2 diabetes (even if they have no symptoms) every 3 years if they are overweight and have at least two risk factors.
Testing for Diabetes and Pre-Diabetes
Pre-diabetes precedes the onset of type 2 diabetes. People who have pre-diabetes have fasting blood glucose levels that are higher than normal, but not yet high enough to be classified as diabetes. (Pre-diabetes used to be referred to as “impaired glucose tolerance.”) Pre-diabetes greatly increases the risk for diabetes.
There are three tests that can be used to diagnose diabetes or identify pre-diabetes:
- Fasting plasma glucose (FPG)
- Oral glucose tolerance test (OGTT)
- Hemglobin A1C (A1C)
Fasting Plasma Glucose Test
The fasting plasma glucose (FPG) test has been the standard test for diabetes. It is a simple blood test taken after 8 hours of fasting. FPG levels indicate:
- Normal. 100 mg/dL (or 5.5 mmol/L) or below
- Pre-Diabetes. Between 100 - 125 mg/dL (5.5 - 7.0 mmol/L)
- Diabetes.126 mg/dL (7.0 mmol/L) or higher
Review Date: 04/01/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.