There are three main types of diabetes: type 1 (which used to be called insulin dependent diabetes or juvenile diabetes), type 2 (which used to known as non-insulin dependent diabetes or adult onset diabetes), and gestational diabetes (experienced by some women during pregnancy). 

The American Diabetes Association, ADA , recommends that all individuals age 45 and above, particularly those with a BMI equal to or greater than 25, should be tested for diabetes, and if the test is normal, they should be re-tested every three years. Testing should be conducted at earlier ages and carried out more frequently in individuals who have any of the following diabetes risk factors:

•  are overweight (BMI equal to or greater than 25)

•  have a first degree relative with diabetes (i.e., parents or siblings)

•  are members of a high-risk ethnic population (African American, Hispanic American, Native American, Asian American or Pacific Islander)

•  have delivered a baby weighing more than 9 pound or have had gestational diabetes

•  have HDL cholesterol levels equal to or less than 35 mg/dl and/or a triglyceride level equal to or greater than 250 mg/dl

•  have high blood pressure

•  on previous testing, had impaired glucose tolerance or impaired fasting glucose.

The ADA recommendations for diagnosing diabetes state that patients should be told they have diabetes if any of the criteria below applies:

• Fasting plasma glucose is equal to or greater than 126 mg/dl;
• Diabetes symptoms exist and casual plasma glucose is equal to or above 200 mg/dl; or
• Plasma glucose is equal to or greater than 200 mg/dl during an oral glucose tolerance test.

If any of these test results occurs, testing should be repeated on a different day to confirm the diagnosis. If a casual plasma glucose equal to 200 mg/dl or above is detected, the confirming test used should be a fasting plasma glucose or an oral glucose tolerance test.