At what age or under what conditions should someone be screened for type 2 diabetes?

When to Screen for Type 2 Diabetes

All adults should be screened starting at age 35 years, with repeat screening every 3 years if normal, or annually if prediabetes is detected. 1 Adults of any age with BMI ≥25 kg/m² (or ≥23 kg/m² for Asian Americans) who have one or more additional risk factors should be screened regardless of age. 2, 1

Age-Based Screening

• Universal screening begins at age 35 years for all adults, representing the most current guideline recommendation. 1
• Older guidelines recommended starting at age 45 years, but this threshold has been lowered to capture younger-onset diabetes. 2
• The rationale for earlier screening is that approximately 19% of new type 2 diabetes diagnoses occur in adults under age 35 years, and nearly half of new diagnoses occur in individuals with normal BMI. 3
• Repeat screening every 3 years if results are normal, or annually in those with prediabetes (A1C 5.7-6.4%, fasting glucose 100-125 mg/dL, or 2-hour glucose 140-199 mg/dL). 2, 1

Risk Factor-Based Screening (Any Age)

Screen adults of any age who are overweight or obese AND have one or more of the following risk factors: 2, 1

Major Risk Factors:

• Physical inactivity 2, 1
• First-degree relative with diabetes (parent or sibling) 2, 1
• High-risk race/ethnicity: African American, Latino, Native American, Asian American, or Pacific Islander 2, 1
• History of gestational diabetes or delivery of baby weighing ≥9 pounds 2, 1
• Hypertension (≥140/90 mmHg or on antihypertensive therapy) 2, 1
• HDL cholesterol <35 mg/dL** and/or **triglycerides >250 mg/dL 2, 1
• Polycystic ovary syndrome 2, 1
• Previous A1C ≥5.7%, impaired glucose tolerance, or impaired fasting glucose 2, 1
• History of cardiovascular disease 2, 1
• Conditions associated with insulin resistance (severe obesity, acanthosis nigricans) 2

BMI Thresholds by Ethnicity

• General population: BMI ≥25 kg/m² triggers screening when combined with risk factors 2, 1
• Asian Americans: Lower threshold of BMI ≥23 kg/m² due to increased diabetes risk at lower body weights 2, 1
• This ethnic-specific threshold is critical because Asian Americans develop diabetes at lower BMI levels, and using the standard 25 kg/m² cutoff leads to missed diagnoses. 2

Screening in Children and Adolescents

Screen overweight children and adolescents (BMI ≥85th percentile for age and sex) starting at age 10 years or at puberty onset (whichever comes first) if they have two or more of the following risk factors: 2

• Maternal history of gestational diabetes during the child's gestation 2
• Family history of type 2 diabetes in first- or second-degree relative 2
• High-risk race/ethnicity 2
• Signs of insulin resistance or conditions associated with insulin resistance (acanthosis nigricans, hypertension, dyslipidemia, polycystic ovary syndrome) 2
• Repeat screening every 2 years in this population 2

Recommended Screening Test

Fasting plasma glucose (FPG) is the preferred screening test because it is faster, easier to perform, more convenient, more acceptable to patients, less expensive, and more reproducible than alternatives. 4

• FPG requires an 8-hour fast and uses a diagnostic threshold of ≥126 mg/dL for diabetes. 1, 4
• Alternative acceptable tests include A1C (≥6.5% indicates diabetes) or 2-hour 75-gram oral glucose tolerance test (≥200 mg/dL indicates diabetes). 2, 1
• Confirm all abnormal screening results with repeat testing on a subsequent day, unless the patient has classic symptoms of hyperglycemia (polyuria, polydipsia, weight loss) with random glucose ≥200 mg/dL. 1, 4

Common Pitfalls to Avoid

• Do not wait until age 45 to screen high-risk individuals—the current guideline is age 35 for universal screening, and any age for those with BMI ≥25 kg/m² plus risk factors. 1
• Do not use BMI ≥25 kg/m² as the threshold for Asian Americans—use ≥23 kg/m² instead to avoid missing diagnoses in this population. 2, 1
• Do not rely on a single abnormal test result—confirmation with repeat testing is required except when classic symptoms are present with random glucose ≥200 mg/dL. 1, 4
• Do not assume normal-weight individuals are low-risk—nearly half of new diabetes diagnoses occur in people with normal BMI, so age-based screening is essential. 3
• Do not screen only symptomatic patients—type 2 diabetes frequently goes undiagnosed for years because hyperglycemia develops gradually, and approximately one-fourth of all people with diabetes in the U.S. are undiagnosed. 2, 1
• Do not forget to consider type 1 diabetes in younger patients or those without typical risk factors—consider islet autoantibody testing (GAD) to exclude type 1 diabetes in these populations. 2, 1

Screening Frequency Algorithm

1. Age ≥35 years with no risk factors: Screen every 3 years 1
2. Any age with BMI ≥25 kg/m² (≥23 kg/m² for Asian Americans) plus ≥1 risk factor: Screen now, then every 3 years if normal 2, 1
3. Prediabetes detected (A1C 5.7-6.4%, FPG 100-125 mg/dL, or 2-hour glucose 140-199 mg/dL): Screen annually 2, 1
4. Children age ≥10 years with overweight/obesity plus ≥2 risk factors: Screen every 2 years 2