Whether you're newly diagnosed, managing type 2 diabetes, or just curious about a result on your lab report — this is where you start. Trustworthy, up-to-date, and plain-spoken.
A1C — technically hemoglobin A1C, sometimes written HbA1c — is a blood test that reflects your average blood sugar over the past two to three months. It works by measuring the percentage of hemoglobin in your red blood cells that has glucose attached to it.
Because red blood cells live about 120 days, a single A1C draw tells a much longer story than a one-time glucose reading. That's why it's the standard test for diagnosing diabetes and tracking how well treatment is working.
Unlike a fasting glucose test, you don't need to skip breakfast. Unlike a finger-stick, it isn't affected by what you ate an hour ago. It's a summary, not a snapshot — which is both its greatest strength and its biggest limitation.
A1C doesn't tell you about day-to-day variability or nighttime lows. For that, continuous glucose monitors (CGMs) have become increasingly common, even for people without diabetes.
These categories come from the American Diabetes Association. Your doctor may set personalized targets based on your age, other conditions, and treatment plan.
No evidence of diabetes. Blood sugar regulation is working as expected.
Elevated risk for developing type 2 diabetes. Often reversible with lifestyle changes.
Diagnostic of diabetes when confirmed by a second test or other criteria.
Untreated diabetes can push A1C to 10% or higher. Most treatment plans for people with diabetes aim for an A1C below 7%, though individual targets vary. See our ADA recommendations page for the full picture.
Ozempic, Wegovy, Mounjaro, Zepbound. Four brand names, two molecules, and a level of effectiveness that has reshaped both diabetes and weight-loss care. Our new comparison guide breaks down how they actually differ.
Read the comparison →Foods that help you manage A1C naturally, plus what to cut back on.
02How and when to test, at the lab or at home.
03Simple, sustainable workouts that lower A1C safely.
04How cortisol affects blood sugar — and what to do about it.
05A guide to prescription medications for blood sugar control.
06Find the right glucose meter or continuous monitor for you.
07Ozempic vs. Wegovy vs. Mounjaro vs. Zepbound, side by side.
08Scientific references behind our guides.
People with well-controlled diabetes are typically tested twice a year. Those changing treatment or not yet at target are usually tested every three months. People without diabetes don't need routine A1C testing unless they have risk factors, though it's increasingly included in standard blood panels.
For many people with prediabetes or early type 2 diabetes — yes. Sustained changes to diet (especially reducing refined carbohydrates), regular physical activity, weight loss, and better sleep can all lower A1C meaningfully. For established diabetes, lifestyle changes work alongside medication rather than replacing it.
Because A1C reflects roughly 2-3 months of average blood sugar, changes show up gradually. You typically see meaningful movement after 6-12 weeks of consistent effort. Don't be discouraged if a single month of hard work doesn't fully register yet.
Same underlying information, different units. A1C is a percentage; eAG translates that into a familiar blood-sugar number (mg/dL or mmol/L). An A1C of 7% corresponds to an eAG of about 154 mg/dL. Some lab reports now show both.
No. Semaglutide (as Wegovy) and tirzepatide (as Zepbound) are FDA-approved for chronic weight management in adults with obesity, or overweight plus a related health condition — regardless of diabetes status. See our GLP-1 comparison for details.