Glycated Hemoglobin: Normal HbA1c and What the Test Shows

The result of a glycated hemoglobin test often leaves people puzzled: they see percentages and do not understand what they mean. Below is an explanation: what HbA1c shows, which values are considered normal, and what the accuracy of the result depends on.

What glycated hemoglobin is and what it shows

Blood glucose binds to hemoglobin, the protein in red blood cells. The higher the glucose level, the larger the proportion of hemoglobin coated with it. The HbA1c test measures the percentage of red blood cells with such coating. The bond is irreversible and persists for as long as the red blood cell lives — about three months (120–125 days). Therefore, the result shows the average glucose level over two to three months, not at the moment of blood collection. Synonyms for the name are glycohemoglobin, glycosylated hemoglobin, A1C. About half of the value is formed by the last 30 days before the test.

What to remember: HbA1c is the average sugar over three months, not a momentary indicator.

Normal glycated hemoglobin in a healthy person

Reference points for diagnosis: normal — below 5.7%, prediabetes — 5.7–6.4%, diabetes — 6.5% and above; in another reference range, normal appears as 4–5.9%. These are reference frameworks: what is normal specifically for you depends on health, age, and other factors. In diabetes, the International Diabetes Federation recommends keeping the indicator below 6.5%, and a value above 8% indicates unsatisfactory control.

What to remember: in a healthy person, the indicator is usually below 5.7%.

Normal HbA1c in women and men: is there a difference

Reference ranges do not contain separate norms by sex. In pregnant women, the result may change, so pregnancy is reported before blood collection; this test is not used to diagnose gestational diabetes. The variation between two people with the same average blood sugar reaches 1% due to differences in laboratory technologies and individual characteristics.

What to remember: reference ranges contain no separate norms for women and men; pregnancy and blood disorders should be reported to the doctor.

What elevated and lowered values mean

Prediabetes means that glucose is above normal but insufficient for a diagnosis of diabetes. At 6.5% and above, the result is usually confirmed by a repeat HbA1c or another test — fasting glucose or an oral glucose tolerance test. A high indicator is associated with the risk of retinopathy, nephropathy, and other complications. A falsely low result occurs after acute blood loss and in hemolytic anemia. In anemia and other blood disorders, renal and hepatic failure, the test may be inaccurate — in that case other studies are discussed, for example fructosamine, which reflects glycemia over 2–3 weeks.

What to remember: a figure above normal is a reason for rechecking, not a ready-made diagnosis.

How the test is performed and what can affect the result

About 3 cm³ of venous blood is taken; there is no need to come fasting. The level does not depend on the time of day, food intake, physical activity, or emotional state. Some medications, for example opioids and certain drugs for the treatment of HIV, can affect the result: everything you take is reported to the doctor. You must not stop taking them on your own.

What to remember: no preparation is needed, but the list of medications and pregnancy must be mentioned.

When to see a doctor

Checking HbA1c is recommended after age 45; if the result is normal, the interval for the next checks is discussed with the doctor. In prediabetes, the test is usually repeated every 1–2 years; in diabetes — at least twice a year. A reason for an unscheduled visit is symptoms resembling manifestations of diabetes:

• severe thirst and frequent urination;
• weight loss without effort and constant hunger;
• blurred vision, numbness or tingling in the hands and feet;
• fatigue, dry skin, slow-healing wounds;
• infections more often than usual.

An elevated or lowered HbA1c by itself is not a reason to call an ambulance. Calling 103 or 112 is necessary for signs of stroke or heart attack.

What to remember: the test result is discussed with a doctor, not interpreted on your own. The material is for reference and does not replace a doctor's consultation.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer