When should diabetes screening and blood glucose monitoring be initiated in adults, and how often should it be repeated based on age and risk factors, including follow‑up testing after diagnosis?

When to Start Diabetes Screening

All adults should begin diabetes screening at age 35 years, with repeat testing every 3 years if results are normal. 1, 2

This represents the most recent guideline update from the American Diabetes Association (2025), which lowered the universal screening age from 45 to 35 years to facilitate earlier detection of metabolic disease that impacts long-term morbidity and mortality. 1, 2

Universal Screening Timeline

• Age 35 years: Begin screening for all adults regardless of risk factors 1, 2
• Every 3 years: Repeat screening if initial results are normal 1, 2
• More frequently: Consider earlier repeat testing if BMI increases or risk factor profile worsens 1, 3

Earlier Risk-Based Screening (Any Age)

Screen adults of any age who have overweight or obesity (BMI ≥25 kg/m² or ≥23 kg/m² in Asian Americans) PLUS one or more of the following risk factors: 1, 3

• First-degree relative with diabetes 1, 3
• High-risk race/ethnicity (African American, Latino, Native American, Asian American, Pacific Islander) 1
• History of cardiovascular disease 1, 3
• Hypertension (≥130/80 mmHg or on antihypertensive therapy) 1, 3
• HDL cholesterol <35 mg/dL and/or triglycerides >250 mg/dL 1, 3
• Polycystic ovary syndrome 1
• Physical inactivity 1, 3
• Conditions associated with insulin resistance (severe obesity, acanthosis nigricans, metabolic dysfunction-associated steatotic liver disease) 1, 3

Important note for Asian Americans: The BMI threshold is lowered to ≥23 kg/m² (instead of ≥25 kg/m²) because this population has higher diabetes risk at lower body weight. 1, 3

Screening Tests to Use

Any of the following three tests are equally appropriate for initial screening: 1, 3

• Fasting plasma glucose (FPG): Requires 8-hour fast 1
• Hemoglobin A1C: No fasting required; stronger predictor of cardiovascular events than fasting glucose 1, 3
• 75-gram oral glucose tolerance test (OGTT): Requires adequate carbohydrate intake (at least 150 g/day) for 3 days prior to testing 1, 3

Post-Screening Follow-Up Intervals

If Normal Results

• Repeat every 3 years minimum 1, 2
• More frequently if symptoms develop or risk factors change (e.g., weight gain) 1, 2

If Prediabetes Detected (A1C 5.7-6.4%, IFG, or IGT)

• Test yearly 1, 3
• Patients with A1C >6.0% are very high-risk with 25-50% five-year progression to diabetes and warrant aggressive intervention 3

If Diabetes Diagnosed

• A1C testing at least twice yearly if meeting treatment goals 2, 4
• A1C testing quarterly if therapy has changed or not meeting goals 2, 4
• Annual screening for chronic kidney disease with urinary albumin and serum creatinine 4

Special Populations Requiring Different Schedules

History of Gestational Diabetes

• Lifelong testing every 1-3 years 1, 3

High-Risk Medications

• Screen adults on glucocorticoids, statins, thiazide diuretics, or certain HIV medications 2

Children and Adolescents

• After onset of puberty or age 10 years (whichever comes first) if overweight/obese with ≥2 additional risk factors 1
• Maternal history of diabetes/gestational diabetes during gestation is the strongest pediatric risk factor 1

Common Pitfalls to Avoid

Do not rely on community screening programs outside healthcare settings: These fail to ensure appropriate follow-up for positive results and repeat testing for negative results, and often inappropriately test low-risk individuals. 1

Do not screen for type 1 diabetes in asymptomatic individuals: Widespread autoantibody testing is not recommended outside of research settings or specialized screening programs for high-risk relatives. 1

Do not forget to confirm abnormal results: In the absence of unequivocal hyperglycemia, diagnostic criteria should be confirmed by repeat testing on a different day. 1

Asian American threshold is critical: Missing the lower BMI cutoff (≥23 vs ≥25 kg/m²) will result in delayed diagnosis in this high-risk population. 1, 3