HbA1c (Glycosylated Hemoglobin)

A normal HbA1c is generally below 5.7% (under 39 mmol/mol). Levels between 5.7% and 6.4% (39–46 mmol/mol) suggest prediabetes, while an HbA1c of 6.5% (48 mmol/mol) or higher on repeat testing indicates diabetes. For people with diagnosed diabetes, treatment targets are often around <7% but should be individualized by age, comorbidities, and hypoglycaemia risk.

For people without diabetes, HbA1c should be under 5.7% (39 mmol/mol); 5.7–6.4% indicates prediabetes. If you have diabetes, most adults aim for about 7.0% (53 mmol/mol) or lower; pregnant women and younger adults may aim for tighter control (~6.5% or below), while older or frail people may have a relaxed target (7.5–8.5%). Individual targets should be set with your clinician.

Glycosylated hemoglobin is a general term for hemoglobin chemically bound to glucose. HbA1c is a specific glycated form—the A1c fraction—reported as a percent (or mmol/mol) of total hemoglobin. HbA1c reflects average blood glucose over the past 2–3 months and is the standard test used to diagnose and monitor diabetes; other glycated hemoglobins exist but are less commonly used.

The HbA1c test measures average blood glucose over the past 2–3 months. In pregnancy it’s used early to detect undiagnosed pre‑existing diabetes and to monitor long‑term glucose control. It is not sensitive for diagnosing gestational diabetes, which is usually identified by an oral glucose tolerance test at 24–28 weeks. An elevated HbA1c (commonly ≥6.5%) suggests probable diabetes and warrants specialist care.

Lower HbA1c quickly by combining medication adherence and physician‑guided treatment adjustments with lifestyle changes: reduce refined carbs and calories, choose low‑Glycemic Index foods, increase regular aerobic and resistance exercise (aim ~150 minutes/week), lose excess weight, monitor blood glucose, and stop smoking and limit alcohol. Rapid changes should be supervised to avoid hypoglycaemia—discuss medication changes with your clinician.

Dangerously high HbA1c is generally considered ≥9–10% (≈75–86 mmol/mol). Levels in this range indicate very poor blood‑glucose control and substantially increased risk of acute problems and long‑term complications (retinopathy, nephropathy, neuropathy, cardiovascular disease). Most treatment targets are <7% (≈53 mmol/mol); values above 8% already raise complication risk and require prompt medical review and treatment intensification.