Does metformin lower A1C, if so how much?

When metformin is used alone as monotherapy, it lowers A1C by about 1% to 2% on average. A1C is a measure of longer-term blood sugar control. In most patients, metformin is suggested as the initial treatment for type 2 diabetes, but its glucose-lowering effect may not be adequate for all patients if used alone.

Metformin is favored over many other diabetes medications as initial treatment because of its ability to control blood sugar levels, lack of weight gain, low risk of hypoglycemia (low blood sugar side effect), its oral formulation and generic availability.

Studies

In metformin clinical studies, obese patients with type 2 diabetes with high blood sugar (hyperglycemia) not controlled by diet alone were started on metformin or placebo.

• Patients received metformin hydrochloride (up to 2,550 mg/day) or a placebo (a pill with no medication).
• After 29 weeks, the mean A1C concentration was 7.1% in the metformin group as compared with 8.6% in the placebo group.

If needed, adding additional glucose-lowering agents can be combined with metformin, including:

• insulin
• oral sulfonylureas (eg, glipizide, glyburide, glimepiride)
• glucagon-like peptide 1 (GLP-1) receptor agonists
• sodium-glucose co-transporter 2 (SGLT2) inhibitors
• dipeptidyl peptidase 4 (DPP-4) inhibitors
• repaglinide
• pioglitazone

What is A1C?

The A1C test, also known as the hemoglobin A1C or HbA1c test, is a simple blood test that measures your average blood glucose levels over the past 3 months. It measures the percentage of your red blood cells (RBCs) that have sugar-coated hemoglobin, a protein in your RBCs. An A1C test result of greater than or equal to 6.5% usually results in a diagnosis of diabetes.

Your doctor may order an A1C test for you every 3 to 6 months while you are taking metformin. You do not need to fast before an A1C test, and you can have this test at any time of the day.

Related Questions

• How long does metformin take to work?
• When is the best time to take metformin?
• What is the safest diabetes medication?

What A1C should I have?

For adults, the American Diabetes Association (ADA) recommends a target A1C of below 7%; however, in 2018, the American College of Physicians (ACP) issued new guidelines with suggested A1C targets between 7% and 8%. Part of the reasoning is to incorporate a more individualized approach to people using type 2 diabetes treatments.

For example, in the elderly, very low blood sugars can be linked with serious health issues, including confusion and fainting, and may not always be appropriate.

You can make a shared decision about treatment and A1C goals when you meet with your physician.

Why is A1C measured?

Your doctor will regularly monitor your A1C to be sure your glucose levels are staying within a healthy range. High blood sugar levels can increase the risk for serious complications due to type 2 diabetes such as:

• vision loss
• peripheral nerve damage
• loss of limbs, amputations
• kidney impairment
• hard-to-treat infections
• impotence and sexual dysfunction
• heart disease

This is not all the information you need to know about metformin for safe and effective use and does not take the place of your health care provider’s directions. Review the full product information and discuss this information and any questions you have with your doctor or other health care provider.