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Erectile Dysfunction - Causes | November 21, 2022, 6:00 CST

Men Are Subject to the Sexual Side Effects of Metformin

The first-line antidiabetic medication may induce erectile dysfunction, according to research.
Three green and white pills are set on a bright blue background.
Illustration by Tré Carden

The ultimate benefit proposition of taking medications is to improve your quality of life. The side effects that accompany them, however, are often unpleasant. Nausea, headaches and fatigue are common side effects of prescription medications.

Then there are the ones that may affect your sexual function.

People with diabetes are not immune to such outcomes. A 2016 study in the Journal of Clinical & Diagnostic Research suggested there are sexual side effects from metformin, a standard treatment method for diabetes. It may play a role in erectile dysfunction (ED) among male patients.

What is metformin?

Metformin is an antidiabetic drug used to manage type 2 diabetes and prediabetes. This medication is meant to lower blood sugar levels and increase insulin sensitivity in patients with type 2 diabetes or prediabetes.

"Metformin decreases glucose production in [the] liver and decreases absorption of glucose in the intestine," said Hiren Italia, M.D., a board-certified physician and prescribing physician at SuperPill in Charlotte, North Carolina, in an email conversation.

Your healthcare provider may prescribe metformin if lifestyle adjustments, such as diet and exercise, aren't enough to manage your blood sugar levels.

Metformin is not always a risk factor for ED

Metformin may affect sexual function, but it's not often the initial cause of ED. Many male patients with diabetes may be experiencing sexual dysfunction before being prescribed the antidiabetic drug. ED is a well-known symptom of diabetes, and the risk factors associated with the chronic disease can also hinder sexual performance.

"It is known that the risk factors for diabetes, such as obesity and sedentary lifestyles, can also be risk factors for reduction in sexual performance," said Ken Perry, M.D., an emergency medicine attending physician in Charleston, South Carolina, in an email conversation.

Side effects of metformin

Taking metformin as part of your diabetes treatment can cause several side effects, ranging from mild to severe, and can affect your overall health.

The potential side effects of metformin can include the following:

  • Abdominal cramps
  • Diarrhea
  • Nausea
  • Upset stomach

Allergic reactions and lactic acidosis are more severe side effects that can occur in rare cases. For example, metformin-associated lactic acidosis (MALA) is a rare and possibly fatal disease that results from a high concentration of plasma metformin and a secondary health condition, such as sepsis or cirrhosis.

The study on the sexual side effects of metformin

The 2016 study in the Journal of Clinical & Diagnostic Research assessed erectile dysfunction and low sex drive among men with diabetes who were taking metformin.

The study included 64 male patients with type 2 diabetes. They were divided based on which diabetic treatments they received or were not receiving. Group A consisted of patients receiving metformin. Group B was patients being treated with the diabetes drug sulfonylurea. Group C included nondiabetic men. In the cross-sectional study, the researchers used the following parameters to compare the groups:

  • Total testosterone (TT)
  • Free testosterone (FT)
  • Free androgen index (FAI)
  • Sex hormone-binding globulin (SHBG)
  • Lipid profile
  • Sexual Health Inventory for Men (SHIM)

The study's results suggest total testosterone, free testosterone, free androgen and SHBG levels were higher in sulfonylurea-treated participants than in patients receiving metformin treatment.

"This study looked at metformin versus a sulfonylurea, another pill for diabetes, and determined that not only were testosterone levels low in the group that had diabetes, metformin further lowered the testosterone in these patients," Perry said.

Additionally, bioavailable testosterone (BT) and SHIM scores were lower in metformin-treated patients compared to sulfonylurea patients and the control group of nondiabetic men.

In short, metformin can significantly reduce a male patient's testosterone levels and sex drive while increasing testosterone-induced ED.

Could you have erectile dysfunction (ED)?

What do the study's results indicate?

Based on the study's conclusions, sulfonylurea may be a viable alternative to metformin, given that participants taking this antidiabetic drug had higher testosterone levels than the patients taking metformin.

"The risk factors for diabetes are also similar risk factors for reduction in sexual performance, and a recent study concludes that metformin, which is a first-line drug for diabetes, may further worsen this performance and, therefore, may not be the best option for all male patients," Perry said.

How to treat metformin's side effects

Switching patients with prediabetes and type 2 diabetes from metformin to sulfonylurea could help resolve the ED issue.

"There are alternatives, such as sulfonylureas like gliclazide, which, in the study, did not appear to impact testosterone levels to the same effect," said Abbas Kanani, M.R.Pharm.S., the superintendent pharmacist at Chemist Click, an online pharmacy in the United Kingdom, in an email conversation. "However, this is not always as simple as a straight swap, and your doctor or endocrinologist will be in the best position to advise."

However, what if a patient declines to switch medications?

A few methods are available to treat metformin-related side effects:

  • Take your pills with a meal to reduce gastrointestinal issues.
  • If your testosterone levels fall, testosterone replacement therapy may help.
  • Your doctor may prescribe ED meds, although they have their own side effects.
  • Surgical intervention is an option in extreme cases.

If you're experiencing side effects from your medications, speak with your doctor to get professional advice on diagnosis and treatment options.

One option that doesn't have side effects is Eddie® by Giddy, an FDA-registered Class II medical device designed to treat erectile dysfunction and improve male sexual performance. Its specific shape optimizes blood flow as it puts pressure on the veins of the penis but not the arteries.

In 2021 clinical trials, Eddie proved effective in treating men with physically, psychologically and pharmacologically induced ED. Of the study participants who used Eddie, 95 percent reported a beneficial effect on their sex lives. Eddie is a safe treatment that does not have the side effects of prescription pills, nor does it require a prescription.