The sneaky sexual side effect of metformin

For men with type 2 diabetes, erectile dysfunction (ED) can be a distressing complication of the condition. The damage caused by the disease can affect the blood vessels and nerves involved in an erection. In fact, men with diabetes are 3 times as likely to develop ED than men without diabetes, according to the Centers for Disease Control and Prevention (CDC).

To complicate matters, metformin — one of the most prescribed medications for the treatment of type 2 diabetes — can also have a negative impact on erections for some men. Some of the drug’s side effects can make it tougher to get an erection. This isn’t always the case, however. In fact, for some men, treating diabetes effectively with metformin can actually improve blood flow and erections. But there’s no way of knowing how it will affect you until you’re taking the medication.

If you’re on metformin and find that it’s causing or worsening ED — or if you’re starting a medicine and are concerned about how it will affect your erections — know that there are solutions.

Together with your doctor, you can navigate the treatment of both conditions in ways that improve your overall health and sex life. Here’s what to know about the different factors at play, and what you can do about ED issues if they do happen. (If you’re already struggling with ED, an Optum doctor can assess whether you’re a good candidate for ED medication, and you can have it delivered to your home, discreetly. Learn more.)

How can diabetes cause or worsen ED?

First, it helps to understand some diabetes basics. Diabetes mellitus is a condition in which the body cannot keep blood sugar (glucose) at healthy levels. That’s usually because the body isn’t making enough of the hormone insulin, which regulates blood sugar. Or it's because your body isn’t responding properly to the insulin it is making.

There are a few different types of diabetes, and type 2 is by far the most common, affecting 90% to 95% of patients, according to the CDC. Type 2 diabetes usually develops slowly over the course of many years. Chronically high levels of blood sugar can lead to serious health issues, including heart disease, nerve damage and kidney disease.

There are several ways that diabetes can affect erections:

• Nerve damage. When the nerves in the penis are damaged, it makes it less responsive to stimulation.
   
• Damage to blood vessels. Because diabetes can impair blood vessels, it may reduce blood flow to the penis. Since erections depend on healthy blood flow to the penile tissues, the result is less firm erections — or none at all.
   
• Other health issues. Diabetes can also indirectly lead to obesity, sleep apnea and depression. All of these conditions can affect your general well-being and can worsen erectile dysfunction.

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How can metformin help or hurt ED?

Because diabetes can be life-threatening and impacts so many bodily systems, your doctor will want to get it under control right away. Medication is also usually part of the plan, along with diet and other lifestyle changes. Metformin is often the first medication of choice.

Metformin works by helping the body make better use of the insulin it has, rather than by spurring the production of more insulin. Metformin is the generic name of the medication, but it also goes by several brand names (Fortamet^®, Glucophage^®, Glumetza^®).

For some, starting metformin will improve ED. That’s because treating diabetes itself can improve erectile function. Also, metformin may raise levels of nitric oxide. Nitric oxide help smake blood vessels more flexible and dilated, increasing blood flow to the penis.

“You hope that by treating diabetes with a medication such as metformin you’ll stabilize or even improve any erectile dysfunction that’s a consequence of the diabetes,” says Marc S. Cohen, MD. He is a urologist and medical adviser at Bastion Health, which specializes in men's reproductive and prostate health. Simply put: Good, early treatment of diabetes is also good early treatment of erection problems caused by the disease.

But that isn’t always the case, says Dr. Cohen. Diabetes treatment may not be able to reverse ED. Also, studies have shown that metformin can reduce testosterone levels, lower sex drive and thus cause erectile dysfunction.

If you’re taking metformin and experiencing ED

If you’re taking metformin and are having issues with ED, there are ways you and your doctor can control your diabetes and keep the home fires burning. Caution: Never stop taking your diabetes medication as a way of dealing with ED — it might even make ED worse.

Explore other diabetes meds. Men who take metformin and experience ED as a side effect do not simply have to put up with it, says Anna Garrett, PharmD, a specialist in hormones and wellnes in Asheville, North Carolina. She’s a pharmacotherapy specialist, which means she’s trained in ensuring the safe and economical use of medications by treatment teams.

Garrett suggests asking your doctor about other medication classes such as sulfonylureas. This group of medicines lower blood sugar levels by stimulating insulin production. Studies show that sulfonylurea medications result in elevated levels of testosterone, along with better erectile function and sex drive.

Consult with a urologist about ED treatments. “If metformin is the only medication that is well-tolerated for diabetes treatment, then ED can be treated separately if it develops,” says Garrett. The doctors most well-versed in treating ED are urologists, and you can work with one alongside your diabetes doctor. A urologist can prescribe an ED medication such as Viagra^® or Cialis^®. (See our guide to ED medications to find out more about each.)

Urologists, as well as other doctors who specialize in ED, also have a range of other treatments at their disposal, depending on the severity of the problem, says Dr. Cohen. These include medications that are injected into the penis, suppositories inserted into the urethra or vacuum erection devices.

“What urologists can offer that other doctors can’t are surgical options,” says Dr. Cohen. Surgical options include penile revascularization, penile reconstruction or penile implants. While they aren’t a starting point for treatment, they can be incredibly valuable for men who want and need them.

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Ask for a testosterone test. “It may be helpful to know your baseline testosterone level,” says Garrett. “If it’s low, you can supplement with testosterone if the metformin drops your testosterone enough to cause ED.”

Get healthier. Regardless of whether you have ED, it’s important to manage your diabetes with lifestyle changes and medication. Some people can send type 2 diabetes into remission with diet and exercise changes, which means they might be able to get off their diabetes medication altogether. But they must still be closely monitored, since the condition is never fully cured.

If you begin to have problems with erections, see your doctor as soon as possible. The earlier you get treatment for ED, the more likely it is that you’ll be able to address it.

The CDC also recommends diabetes self-management and support services. These services offer guidance on diet and how to test your blood sugar, as well as suggest ways to keep active and cope with the emotional aspects of living with diabetes. When the condition is well-managed, you’ll feel better overall — which most men agree will make for a happier sex life, too.

The Optum Store is here to help you, too. Learn more about our services for erectile dysfunction. 

Additional sources
Effects of metformin: Translational Andrology and Urology (2017). "Effects of Metformin on Endothelial health and Erectile Dysfunction"

Diabetes and ED:
• Centers for Disease Control and Prevention (2021). "Diabetes and Men"
• Cleveland Clinic (2020). "The Link Between Diabetes and Sexual Dysfunction"

Testosterone, metformin and sulfonylurea: Journal of Clinical and Diagnostic Research (2016). "Erectile Dysfunction and Low Sex Drive in Men With Type 2 DM"

Metformin and diabetes: Drug Design, Development and Therapy (2017). "Metformin: Review of Its Potential Indications"

Diabetes in remission: The Lancet (2021). Defining Type 2 Diabetes Remission