The prediabetes A1c range

Category	A1c	Estimated average glucose
Normal	Below 5.7%	Below 117 mg/dL (6.5 mmol/L)
Prediabetes	5.7% to 6.4%	117 to 137 mg/dL (6.5 to 7.6 mmol/L)
Diabetes	6.5% or higher	140 mg/dL or higher (7.8 mmol/L)

What the range means

• The ADA defines prediabetes as an A1c of 5.7% to 6.4%; it can also be defined by fasting glucose or the OGTT (ADA Standards 2026, sec. 2).
• Prediabetes is a risk factor for type 2 diabetes. Within the range, the higher the A1c, the higher the risk (NIDDK).
• If you have no symptoms, a result in this range is usually confirmed with a repeat test on another day (NIDDK).
• The range is the same at every adult age, although A1c tends to drift up a little with age. See A1c by age.

What the DPP trial found

The Diabetes Prevention Program randomly assigned adults with raised glucose to an intensive lifestyle program, metformin, or placebo. The lifestyle program aimed for 7% weight loss and at least 150 minutes of physical activity a week. Over an average of 2.8 years, type 2 diabetes developed 58% less often with the lifestyle program and 31% less often with metformin than with placebo (DPP 2002).

NIDDK says type 2 diabetes may be prevented or delayed with changes such as weight loss and being active most days of the week (NIDDK). Ask your doctor whether a program like this is right for you.

Key values in this range

A1c 5.7% · A1c 6.0% · A1c 6.4% · A1c 6.5% (diabetes threshold)