Metformin and ED: Is There a Connection?

Diabetes mellitus, or type 2 diabetes, is one of the most common chronic diseases in the United States, and it is becoming increasingly more prevalent around the world.

Diabetes is associated with many health conditions, including increased risk of cardiovascular disease and obesity, but its connection to sexual dysfunction is being discussed with greater regularity.

Diabetes is an established risk factor for erectile dysfunction because the disease can damage the tiny blood vessels and nerves that work together to trigger an erection.

Man looking at Rx bottle

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In fact, men with diabetes are three times more likely to have erectile dysfunction (ED) compared to those who do not have diabetes. They also often experience ED earlier, sometimes by as much as 10 to 15 years, than their peers without diabetes.

Diabetes alone can lead to ED because high blood sugar levels are toxic to nerves and blood vessels, which are necessary to achieve and maintain erections, but treatment can help. Metformin, a commonly prescribed diabetes medication, was once thought to help ED.

However, more recent research shows that sexual dysfunction may be a side effect of metformin, and that it may cause a significant lowering of testosterone levels.

Current research estimates approximately 462 million people were affected by type 2 diabetes in 2017, and the number is expected to rise to 552 million by 2030.

This article will discuss what the research shows about metformin and ED.

Diabetes and Erectile Dysfunction

The development of erectile dysfunction in people with diabetes is a gradual process that includes both vascular and neurological mechanisms.

Normal erections require blood flow into the penis. During sexual arousal, neurological signals from the brain are sent to the penis. Nitric oxide, a potent vasodilator that promotes blood flow, is activated.

Nitric oxide causes rapid and short-term increases in penile blood flow and short-term relaxation of the penile smooth muscle. As blood fills up the penis, the outflow of blood is restricted, allowing a man to acquire and maintain a firm erection.

Diabetes contributes to ED in three distinct ways:

  1. High glucose levels damage blood vessel walls, modifying the enzyme that activates the endothelial nitric oxide synthase enzyme. This prevents the rapid increase in blood flow to the penis, making it more difficult to achieve and maintain an erection.
  2. Diabetes is often associated with atherosclerosis, a condition that limits blood throughout the body. In those with diabetes and ED, atherosclerosis in the penile and pudendal arteries limits the flow of blood into the spongy chamber of the penis that becomes hard (the corpus cavernosum).
  3. High blood sugar can damage nerves, causing a condition called autonomic neuropathy. This can result in a loss of the autonomic nerve-mediated muscle relaxation that is essential for erections.

Some men with longstanding diabetes may also complain of symptoms of hypogonadism such as low testosterone and/or low sperm production. Diabetes management is important in preventing the development of hypogonadism.

Treating diabetes with medication and lifestyle changes can improve blood flow and nerve sensitivity, which may help in managing ED caused by diabetes complications.

Metformin and ED in Focus

Metformin is a popularly prescribed medication for the treatment of type 2 diabetes. It works by reducing the amount of sugar your liver releases into your blood. It also improves your body’s response to the blood sugar-regulating hormone insulin.

Metformin is capable of improving ED by managing some of the side effects of diabetes that can cause ED. One recent study showed that metformin treatment positively affects two of three pathways that contribute to ED, including:

  • Activating the nitric oxide response required to increase blood flow to the penis
  • Moderating sympathetic nerve activity

The combination of these two effects should help improve ED.

However, other studies have found that metformin may be associated with a reduced output of testosterone, which can cause reduced sex drive and may contribute to ED.

More research is needed to determine the effect of metformin on erectile function.

If you are taking metformin for diabetes and notice reduced sex drive or increased ED, don’t hesitate to talk with your healthcare provider. The options below can help you get your sex life back on track, while also managing your diabetes.

ED Drugs and Diabetes

Erectile dysfunction treatments are generally well tolerated, even by people with diabetes if they are in otherwise generally good health.

Phosphodiesterase type 5 inhibitors (PDE5i), like Cialis (tadalafil) and Viagra (sildenafil), are the first-line treatment options for people with diabetes and ED.

Penile injections of vasoactive drugs, like alprostadil, are commonly used as a second-line medical treatment when PDE5i has failed. Alprostadil is also available as a urethral suppository for those who prefer a non-injectable form of therapy.

Despite the effectiveness of drug therapy for ED, it is important to manage your diabetes with medication and lifestyle changes; otherwise, your ED will likely progress in spite of drug treatment. Additionally, ED drugs may increase your heart rate or interact with other drugs that you are taking, so you should never start taking these drugs without first consulting with your healthcare provider.

ED drugs are generally not recommended for people with severe cardiovascular disease or urinary tract issues. Therefore, people with diabetes should talk with their healthcare provider about their risk for kidney problems and heart disease prior to starting any ED medication. 

A Word From Verywell

Metformin is generally safe, but some researchers do cite erectile dysfunction as a potential side effect due to the drug’s effects on testosterone production. More recent research has found that metformin can help treat ED indirectly by addressing diabetes and other risk factors.

Making lifestyle changes such as eating a healthy diet, exercising regularly, and quitting smoking increases the potential effectiveness of metformin both in managing diabetes and ED.

8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Shamard Charles, MD, MPH
Shamard Charles, MD, MPH is a public health physician and journalist. He has held positions with major news networks like NBC reporting on health policy, public health initiatives, diversity in medicine, and new developments in health care research and medical treatments.