Hemoglobin A1C under 5.7 %

The 2026 Standards of Care never print a row called normal. They define prediabetes as the range between normoglycemia and diabetes, and everything under 5.7 percent sits in the normoglycemia region by that definition. The Standards also warn that risk does not stop at the line: the footnote to their prediabetes table says risk "is continuous, extending below the lower limit of the range and becoming disproportionately greater at the higher end of the range." A 5.6 is not a different kind of result from a 5.7.

What the ADA says to do next. Recommendation 2.12c: after a normal screening result, repeat screening "at a minimum of 3-year intervals is reasonable, sooner with symptoms or change in risk (e.g., weight gain)." The Standards give their reason for three years in plain terms: it keeps false positives down while making sure a false negative is caught "before substantial time elapses and complications develop." They add that people with earlier values near the diagnostic cut point, or on medications that raise glucose, may warrant shorter intervals. A result close to a threshold gets its own instruction: repeat the test in 3 to 6 months.

Who gets screened at all. Recommendation 2.12b sets the default start at age 35 for everyone. Recommendation 2.12a moves it to any age for adults with overweight or obesity (BMI 25 or higher, 23 or higher for people of Asian ancestry) who carry one or more of the Table 2.5 risk factors: a first-degree relative with diabetes, high-risk race or ethnicity, cardiovascular disease, blood pressure of 130/80 or higher, HDL under 35 or triglycerides over 250, polycystic ovary syndrome, physical inactivity, or another condition tied to insulin resistance.

Two caveats the Standards attach to a normal A1C. First, A1C has "lower sensitivity" at its cut point than the 2-hour glucose test, so a normal A1C does not rule out the abnormal glucose tolerance an OGTT would find. Second, Recommendation 2.4 says plasma glucose, not A1C, should be used to diagnose diabetes when something alters the relationship between A1C and glucose: some hemoglobin variants, pregnancy, G6PD deficiency, HIV, and conditions that change red blood cell turnover such as anemia, blood loss, transfusion, or kidney failure. In those situations a normal A1C is not evidence of normal glucose.