Font Size

Hemoglobin A1c (HbA1c) (cont.)

When Should Hemoglobin A1c Levels Be Tested?

In addition to random fasting blood glucose levels, HbA1c levels are routinely measured (tested) in the monitoring of people with type 1 and type 2 diabetes. HbA1c levels depend on the blood glucose concentration. That is, the higher the glucose concentration in blood, the higher the level of HbA1c. Levels of HbA1c are not influenced by daily fluctuations in the blood glucose concentration but reflect the average glucose levels over the prior six to eight weeks. Therefore, HbA1c is a useful indicator of how well the blood glucose level has been controlled in the recent past (over two to three months) and may be used to monitor the effects of diet, exercise, and drug therapy on blood glucose in people with diabetes.

How Can a Person Lower Their HbA1c Levels?

Following your type 1 or type 2 diabetes management plan can help lower your HbA1c level. This may consist of

  • dietary modifications,
  • physical activity,
  • medications,
  • a combination of these.

A normal or only slightly elevated HbA1c level is an indication that your diabetes is under good control. If your HbA1c level remains high despite following your treatment plan, your doctor may suggest changing your treatment plan.

What Are the Limitations to Measuring Hemoglobin A1c?

Since HbA1c is not influenced by daily fluctuations in blood glucose concentration, it cannot be used to monitor day-to-day blood glucose concentrations and is inappropriate to be used for adjusting insulin doses; nor can it detect the day-to-day presence or absence of hyperglycemia or hypoglycemia. HbA1c may be increased falsely in certain medical conditions. These conditions include

Medical conditions that may falsely decrease HbA1c include


American Diabetes Association. "A1C and eAG." Sept. 29, 2014. <>

Horowitz, Gary L. "Hemoglobin A1c Testing." Sept. 15, 2015. <> HbA1c test. Sep 2016.

Medically Reviewed by a Doctor on 9/19/2017

Must Read Articles Related to Hemoglobin A1c (HbA1c)

Diabetes: Caring for Your Diabetes at Special Times
Caring for Your Diabetes at Special Time Be prepared to manage your diabetes, and control blood sugar and symptoms when you're sick, when you're at work or school, when traveling, during pregnancy, or ...learn more >>
Diabetes (Type 1 and Type 2)
Diabetes (Mellitus, Type 1 and Type 2) There are two types of diabetes, type 1 (insulin dependent), and type 2 (non-insulin dependent). learn more >>
Diabetic Emergency
Diabetes Blood Sugar Emergencies Skip Caray, legenday Atlanta Braves baseball announcer, died of complications from learn more >>

Patient Comments & Reviews

The eMedicineHealth doctors ask about Hemoglobin A1c Test (HbA1c) :

HbA1C Test - High Levels

Are the test results for your HbA1c levels high? If so, what things have been helpful in lowering your HbA1c blood levels and are they working?

Hemoglobin - Treatment

Please describe how monitoring your hemoglobin levels has helped with the treatment of your condition.

Hemoglobin Levels - Experience

Please describe your experience with hemoglobin levels.

Read What Your Physician is Reading on Medscape

Retinopathy, Diabetic, Background »

Diabetes mellitus (DM) is a major medical problem throughout the world.

Read More on Medscape Reference »

Medical Dictionary