Most adults should start screening for type 2 diabetes at age 35, then repeat the test every three years. That recommendation, updated in 2022 by the American Diabetes Association and supported by the U.S. Preventive Services Task Force, lowered the starting age from the previous threshold of 45. But several common risk factors can push that timeline earlier, sometimes by decades.
The Standard Starting Age
For adults without obvious risk factors, routine screening for prediabetes and type 2 diabetes begins at 35. The USPSTF specifically recommends screening adults aged 35 to 70 who are overweight or obese. The ADA’s broader recommendation covers all adults starting at 35, regardless of weight. If your initial result comes back normal, the standard advice is to rescreen every three years.
That three-year interval is a general guideline, though. Research on optimal screening frequency suggests the ideal gap depends on your individual risk level. People whose blood sugar sits at the higher end of normal (an A1C between 5.7% and 6.0%) benefit from retesting every two years, while those with results well within the normal range could safely wait up to five years.
Risk Factors That Move Screening Earlier
If you carry extra weight and have at least one additional risk factor, screening should begin before 35. Those risk factors include:
- Family history: a parent or sibling with type 2 diabetes
- Ethnicity: Native American, African American, Latino, Asian American, or Pacific Islander heritage
- Physical inactivity
- High blood pressure
- Abnormal cholesterol: low HDL or high triglycerides
- History of cardiovascular disease
- Polycystic ovary syndrome (PCOS)
- Previous gestational diabetes or delivering a baby over 9 pounds
- A previous borderline result on any blood sugar test
Any one of these, combined with a BMI of 25 or higher, is enough reason to get tested regardless of age. The more risk factors you have, the stronger the case for early and more frequent screening.
Why Ethnicity Matters for Screening
Diabetes risk doesn’t distribute evenly across ethnic groups, and the standard weight thresholds can be misleading. A large population study found that South Asian individuals develop type 2 diabetes at the same rate as White individuals who are significantly heavier. Specifically, a South Asian person at a BMI of about 24 carries the same diabetes risk as a White person at a BMI of 30. That’s a striking gap: a BMI of 24 is technically “normal weight” by conventional standards.
Black, Chinese, and Arab populations also face elevated risk at lower BMI levels than White populations, though the difference is less dramatic than for South Asian groups. This is why major guidelines flag certain ethnic backgrounds as independent risk factors. If you’re Asian American, for instance, screening is worth discussing with your doctor even at a BMI below 25.
Screening During Pregnancy
Gestational diabetes has its own screening timeline. Most pregnant people are tested between 24 and 28 weeks, during the second trimester. If you’re at higher risk (due to obesity, a previous pregnancy with gestational diabetes, or a strong family history of diabetes), your provider will likely test you at your first prenatal visit instead of waiting.
A history of gestational diabetes also places you in a higher-risk category for type 2 diabetes later in life. That means more vigilant screening after pregnancy, not just during it.
Screening for Children and Teens
Type 2 diabetes in young people is rising, and guidelines now recommend risk-based screening starting at age 10 or the onset of puberty, whichever comes first. The child must be overweight (at or above the 85th percentile for BMI) and have at least one additional risk factor. Those include a mother who had diabetes or gestational diabetes during that pregnancy, a first- or second-degree relative with type 2 diabetes, belonging to a high-risk ethnic group, or showing signs of insulin resistance like darkened skin patches on the neck or underarms (a condition called acanthosis nigricans).
This isn’t universal screening for all kids. It targets children who carry a real and measurable risk profile.
What the Tests Actually Measure
The most common screening test is the A1C, a blood test that reflects your average blood sugar over the past two to three months. No fasting required. The ranges are straightforward:
- Normal: below 5.7%
- Prediabetes: 5.7% to 6.4%
- Diabetes: 6.5% or higher
A fasting blood sugar test and a glucose tolerance test (where you drink a sugary solution and have your blood drawn afterward) can also be used. Your provider may choose one over another depending on the situation, but all three are considered valid for diagnosis.
What Happens If You’re in the Prediabetes Range
A prediabetes result isn’t a diabetes diagnosis. It’s a signal that your blood sugar is elevated but hasn’t crossed the threshold yet. About 38% of U.S. adults fall into this range, so it’s extremely common.
The practical value of catching prediabetes is that it responds well to lifestyle changes. Modest weight loss (5% to 7% of body weight) and regular physical activity can significantly reduce the odds of progressing to full diabetes. If your A1C lands between 5.7% and 6.0%, retesting every one to two years is reasonable. If it’s between 6.1% and 6.4%, closer to the diabetes cutoff, retesting every seven months to a year makes more sense so that any progression gets caught quickly.
If your doctor suspects prediabetes but your initial test comes back normal, a repeat test within a year or a different type of blood sugar test can help confirm the result. No single test is perfect, and catching the trend matters more than any one number.