Starting Age for Annual Blood Tests in Adults
For adults without significant medical history but with possible risk factors like family history, routine blood testing should begin at age 35 years, with repeat testing every 3 years if results are normal. 1, 2, 3
General Population Screening Framework
The most recent guidelines establish age 35 as the universal starting point for metabolic screening in asymptomatic adults, regardless of risk factors. 1, 2, 3 This represents a shift toward earlier detection of metabolic diseases that can impact long-term morbidity and mortality.
Core Laboratory Tests Starting at Age 35
Diabetes screening should begin at age 35 using fasting plasma glucose, 2-hour plasma glucose during 75-g oral glucose tolerance test, or A1C. 1, 2, 3 If results are normal, repeat testing at minimum 3-year intervals is recommended, with more frequent testing if risk factors develop (such as weight gain). 1, 2
Lipid profile testing should begin between ages 40-70 years for cardiovascular risk assessment, though for adults aged 21-39 years, testing is based on clinical judgment and presence of cardiovascular risk factors. 2, 3
Blood pressure measurement should occur at every clinical visit regardless of age, with annual screening recommended for all adults. 2, 3
Risk-Based Earlier Screening (Before Age 35)
For adults of any age with overweight or obesity (BMI ≥25 kg/m² or ≥23 kg/m² in Asian Americans) who have one or more risk factors, testing should be considered earlier. 1, 3 These risk factors include:
- 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
- Hypertension (≥130/80 mmHg or on therapy) 1
- Abnormal lipids (HDL <35 mg/dL and/or triglycerides >250 mg/dL) 1
- Physical inactivity 1
- Conditions associated with insulin resistance (polycystic ovary syndrome, severe obesity, acanthosis nigricans) 1
Testing Frequency Algorithm
If initial tests are normal:
- Repeat screening at minimum 3-year intervals 1, 2, 3
- Consider more frequent testing with symptoms or change in risk status (e.g., weight gain) 1
If prediabetes is detected (A1C 5.7-6.4%, impaired fasting glucose, or impaired glucose tolerance):
- Test yearly 1
If diabetes is 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
Special Populations
Adults with gestational diabetes history should have lifelong testing at least every 3 years. 1
Adults on certain medications (glucocorticoids, statins, thiazide diuretics, some HIV medications) should be screened for prediabetes or diabetes. 1
Adults age 65 and older should receive annual screening for cognitive impairment in addition to metabolic testing. 2
Common Pitfalls to Avoid
Do not delay screening until age 50 in patients with family history or other risk factors—the age 35 threshold applies to all adults, with earlier testing indicated for those with risk factors. 1, 2, 3
Do not rely on annual testing as routine—the evidence supports 3-year intervals for those with normal results, reserving annual testing for those with prediabetes or specific risk factors. 1, 2
Do not screen with only one test type—comprehensive metabolic assessment requires consideration of glucose metabolism (via fasting glucose, OGTT, or A1C), lipid profile, and blood pressure. 1, 2, 3
Do not ignore family history as a trigger for earlier screening—a first-degree relative with diabetes is a specific indication for risk-based screening before age 35 if the patient has overweight or obesity. 1, 3