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Also: HbA1c · hemoglobin A1c
A blood test that measures average blood glucose over the previous ~3 months. The standard marker for diabetes control. Most labs report it as a percentage (5-15%); under 5.7% is normal, 5.7-6.4% is prediabetes, 6.5%+ usually indicates diabetes. Goal A1c varies by patient — tighter targets for younger patients, looser targets for frail older adults.
A1c measures the percentage of hemoglobin in red blood cells that has glucose attached. Because red blood cells live ~3 months, A1c reflects average blood sugar over the prior 60-90 days — a much more stable measure than a single fingerstick. It's the canonical metric for diabetes control.
Interpretation: • <5.7% — normal • 5.7-6.4% — prediabetes • ≥6.5% — diabetes (confirmed with a second test or fasting glucose)
Approximate A1c → average glucose conversion: • 6.0% ≈ 126 mg/dL • 7.0% ≈ 154 mg/dL • 8.0% ≈ 183 mg/dL • 9.0% ≈ 212 mg/dL • 10.0% ≈ 240 mg/dL
**A1c targets are NOT one-size-fits-all.** The American Diabetes Association recommends: • Most adults: <7.0% • Newly-diagnosed, no comorbidities, long life expectancy: <6.5% • Older adults, frail, or with limited life expectancy: 7.5-8.0% (looser is intentionally safer) • Very frail or end-of-life: 8.5% or even just symptom-focused management
Why looser is better for some patients: the harm of hypoglycemia (low blood sugar from too-aggressive control) is severe in frail older adults — falls, confusion, fractures, sometimes death. A tighter A1c target requires more aggressive insulin or oral medications, which raises hypoglycemia risk. For an 85-year-old with multiple comorbidities, the long-term diabetes complications take decades to develop; the short-term hypoglycemia risk is immediate. The right target is the one where the patient is symptom-free with the lowest hypoglycemia risk.
What else affects A1c: • Anemia or recent blood loss can artificially lower A1c (less hemoglobin to measure) • Some hemoglobin variants (sickle cell trait, thalassemia) affect the test accuracy • Chronic kidney disease can affect A1c interpretation • Pregnancy uses different targets and different metrics
Family tracking: A1c trended over time tells a story — going up means control is slipping; going down means treatment is working. The single value matters less than the trajectory. Kintaria's lab-trends feature charts A1c alongside blood pressure, weight, and kidney function (eGFR) for the full diabetes picture.
At every diabetes-related visit (usually 2-4 times per year). Useful to track over time — a Kintaria workspace charts the trend automatically.
Terms families frequently confuse with a1c.
A1c measures diabetes control; eGFR measures kidney function. Both matter in diabetes care — high A1c over years damages kidneys, which is reflected in declining eGFR. Tracking both together gives the full picture of how diabetes is affecting the body.
See also: all glossary terms · conditions by name · step-by-step playbooks