5 Surprising Metformin Benefits Beyond Blood-Sugar Control
What if the medication you’re taking for blood sugar control could also protect your vision? New research reveals a surprising connection between metformin and eye health—and doctors say vision support may not be the only bonus benefit. If you have type 2 diabetes or prediabetes, you’ve likely heard of this prescription medication. In fact, according to UC Health, an estimated 200 million people worldwide take it to prevent or treat type 2 diabetes. While it’s best known for helping manage blood sugar, our experts say the potential benefits of metformin extend far beyond diabetes control. Here’s what you need to know.
What is Metformin?
“Metformin is a medication that is used as a first-line treatment for type 2 diabetes,” says Jennifer Chung, MD, a board-certified internist and former primary care physician with more than a decade of clinical experience. “It works by several mechanisms, mainly through decreasing the production of glucose by the liver, reducing the absorption of glucose from the intestinal tract and increasing insulin sensitivity.”
Lynn Westphal, MD, board-certified ob-gyn and Medical Director at Musely, says metformin is usually very safe for most people. (The most common side effects are GI upset.) However, she notes that it may not be a good fit for those with serious kidney problems or for people with advanced liver disease.
A word of advice: “Be sure to take a multivitamin that contains vitamin B12 with metformin, otherwise [the medication] can cause B12 deficiency,” adds Jacob Teitelbaum, MD, author of From Fatigued to Fantastic.
Dr. Westphal emphasizes that the medication should always be taken under a doctor’s guidance with proper monitoring.
New research on metformin benefits for eye health
With age often comes changes in vision, including an increased risk of age-related macular degeneration, (AMD). The condition will affect an estimated 200 million people globally this year, according to Eye Health Central.
“Age-related macular degeneration is a common eye condition in adults over 50 years old,” explains Dr. Chung. “It is due to a combination of factors such as aging, genetic risk and environmental risk factors that lead to gradual damage, or degeneration, of the macula. The macula is the part of the retina that is responsible for sharp, central vision. Damage to the macula leads to blurry vision and difficulty seeing details directly in front of you.”
A new study published in BMJ Open Ophthalmology followed more than 2,000 adults over age 50 living with type 2 diabetes for five years. Researchers took retinal images at the start and end of the study, and found those taking metformin had a 37 percent lower risk of developing a more advanced stage of age-related macular degeneration.
Eve Elizabeth K. Pennie, MD, a general practitioner and clinical research professional with experience in epidemiology and clinical trial management, says the study findings point to a protective association between retinal health in people living with diabetes and taking metformin.
Why? Dr. Pennie explains that metformin has anti-inflammatory and antioxidant effects that may help protect the cells in the back of the eye from damage caused by long-term high blood sugar and harmful molecules that build up in the body over time. She says it can also improve blood vessel function, which may enhance circulation to the eyes, reducing damage linked to poor blood flow.
4 other surprising metformin benefits
Better eye health is not the only health benefit you may experience when taking metformin. Dr. Westphal says other potential benefits include:
Heart protection
Metformin has been linked to a lower risk of cardiovascular events, such as heart attacks, in people living with diabetes.
“Cardiovascular protection may be due to anti-inflammatory effects, improved endothelial function and favorable effects on lipid profiles,” Dr. Westphal explains.
Weight stabilization
The drug may support modest weight loss by helping the body use insulin more efficiently and, in some people, curbing appetite, explains Dr. Westphal. Better insulin sensitivity can help reduce fat storage and stabilize hunger cues.
Healthy aging
Dr. Westphal says there’s growing interest in whether metformin could play a role in healthy aging. Scientists are studying how it activates AMPK, a cellular “energy sensor,” and how it supports mitochondrial function, meaning how efficiently our cells produce energy. Researchers are also examining its effects on inflammation, since energy regulation and inflammation are closely linked to the aging process.
Lower cancer risk
Some observational studies have linked metformin use to lower rates of certain cancers, possibly because the medication lowers insulin and helps keep blood sugar and metabolism more stable, Dr. Westphal explains. She adds that scientists are still studying this connection.
If you’ve recently been prescribed metformin or are considering starting it, there’s good reason to feel optimistic. This widely used, well-studied medication may support your health in a multitude of ways.
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This story was originally published March 2, 2026 at 12:30 PM.