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Hemoglobin A1c, commonly known as HbA1c or glycated hemoglobin, is a crucial blood test that measures the average blood sugar levels over the past two to three months. This test is essential for diagnosing and monitoring diabetes. Unlike daily blood glucose tests that provide a snapshot of sugar levels at a specific moment, the HbA1c test offers a comprehensive picture of long-term glucose control. When glucose circulates in the blood, it attaches to hemoglobin, the protein in red blood cells that carries oxygen. The more glucose present in the blood, the more hemoglobin becomes glycated. Since red blood cells live for approximately three months, the HbA1c test reflects average blood sugar levels during that period.

The HbA1c test is recommended for several groups of people. Adults aged 45 and older should consider getting tested, especially if they are overweight or have other diabetes risk factors. Younger individuals who are overweight and have additional risk factors such as family history of diabetes, sedentary lifestyle, high blood pressure, abnormal cholesterol levels, or a history of gestational diabetes should also be tested. For people already diagnosed with diabetes, regular HbA1c testing helps monitor how well treatment plans are working and whether adjustments are needed. The test requires no special preparation and can be done at any time of day without fasting, making it convenient for patients.

The results of the HbA1c test are expressed as a percentage. For people without diabetes, normal levels are typically below 5.7 percent. Levels between 5.7 and 6.4 percent indicate prediabetes, a condition where blood sugar is higher than normal but not yet high enough to be classified as diabetes. An HbA1c level of 6.5 percent or higher on two separate tests indicates diabetes. For those already diagnosed with diabetes, the American Diabetes Association generally recommends maintaining an HbA1c level below 7 percent, though individual targets may vary based on age, overall health, and other factors.

Several factors can affect HbA1c test results and should be considered when interpreting the values. Conditions that affect red blood cell turnover, such as recent blood loss, blood transfusions, or certain types of anemia, can lead to inaccurate results. People with hemoglobin variants or certain kidney or liver diseases may also experience discrepancies. Additionally, some medications and supplements can influence test results. If HbA1c results seem inconsistent with daily blood sugar readings or if there are concerns about accuracy, healthcare providers may recommend alternative tests or more frequent monitoring to ensure proper diabetes management.