Guidelines on Diabetes Screening

Who Should Be Screened

The American Diabetes Association recommends that all adults should begin screening for prediabetes and type 2 diabetes at age 35 years, with earlier screening for those with overweight/obesity and additional risk factors 1
Adults with overweight or obesity (BMI ≥25 kg/m² or ≥23 kg/m² in Asian Americans) who have one or more of the following risk factors should be considered for testing: first-degree relative with diabetes, high-risk race/ethnicity, history of cardiovascular disease, hypertension, low HDL cholesterol and/or high triglycerides, polycystic ovary syndrome, physical inactivity, or other insulin resistance conditions 2, 1

If initial screening results are normal, repeat testing at minimum 3-year intervals is reasonable, but more frequent screening should be considered sooner with symptoms or change in risk factors such as weight gain 1
People with prediabetes should be tested yearly 2

Three tests are equally appropriate for screening: fasting plasma glucose, 2-hour plasma glucose during 75-g oral glucose tolerance test, and HbA1c, each with distinct advantages and limitations 1, 4
Fasting plasma glucose requires an 8-hour fast, and diabetes diagnosis is made at ≥126 mg/dL, while prediabetes is diagnosed at 100-125 mg/dL 4
2-hour OGTT requires adequate carbohydrate intake for 3 days prior to testing, and diabetes diagnosis is made at ≥200 mg/dL, while prediabetes is diagnosed at 140-199 mg/dL 1, 4
HbA1c is convenient, with no fasting required, and diabetes diagnosis is made at ≥6.5%, while prediabetes is diagnosed at 5.7-6.4% 4

Risk-based screening should be considered after the onset of puberty or after 10 years of age, whichever occurs earlier, in children and adolescents with overweight or obesity who have one or more risk factors, including maternal history of diabetes, family history of type 2 diabetes, high-risk race/ethnicity, or signs of insulin resistance 1, 2

Screening for type 1 diabetes risk through islet autoantibody testing can effectively identify individuals who will develop type 1 diabetes, with a nearly 70% risk of developing type 1 diabetes within 10 years and 84% within 15 years for those with more than two autoantibodies 1

All screening should be done as part of a healthcare office visit, not as standalone community screening, and positive test results should be confirmed on another day, except when random plasma glucose is ≥200 mg/dL with classic symptoms of hyperglycemia 5, 4
Plasma glucose must be measured in an accredited laboratory when used for diagnosis or screening, using tubes containing rapidly effective glycolytic inhibitor such as granulated citrate buffer 6