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Does Metformin Benefit People With Type 1 Diabetes?

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Metformin is a commonly prescribed medication for people with type 2 diabetes. However, some experts see benefits in prescribing the drug to certain people with type 1 diabetes, too. Here’s what you should know. 

You may already know that metformin is a popular medication for people with type 2 diabetes. What you might not be aware of is that a number of people with type 1 diabetes also take metformin to help with issues like insulin resistance, excess weight, and reducing heart disease risk. 

In the U.S. and most other countries, metformin is only approved for use in people with type 2 diabetes (one exception to this is France, where it’s been approved for type 1 since 1996). But for years, some healthcare professionals have been prescribing the drug to certain individuals with type 1 “off-label,” meaning it hasn’t been approved for this condition. 

In Scotland, for instance, about 15% of adults with type 1 have been prescribed metformin, according to 2016 data. The U.K.’s national diabetes care guidelines recommend that providers consider prescribing metformin off-label to people with type 1 diabetes who have a body mass index above 25 (or 23 and above for Asians and Asian American adults) and want to optimize their blood sugar levels while minimizing insulin use. 

Why? Experts suggest that the benefits of metformin, such as increased insulin sensitivity and modest weight loss, also apply to people with type 1 struggling with these issues, said Dr. Amy Chang, an endocrinologist at Scripps Health. 

How metformin may help type 1 diabetes

Experts are increasingly recognizing that medications initially intended for people with type 2 diabetes may also support some with type 1

Chang has seen firsthand in her practice that many individuals with type 1 diabetes experience a wide variety of positive changes on metformin. Mainly, it helps to keep blood sugars in range using less insulin and lose excess body weight at the same time. In some cases, she’s also seen greater time in range and lower cholesterol. 

“That's where medications traditionally for type 2 diabetes can actually be helpful,” Chang said. 

Jenna Brothers, a diabetes care and education specialist and endocrinology physician assistant at Duke Health, also prescribes metformin to people with type 1 diabetes who are facing insulin resistance and weight gain. 

“Metformin provides them with extra help to make the insulin they're taking work a little bit better,” Brothers explained. “In turn, that usually helps them lose a small amount of weight – maybe five to 10 pounds.” 

All of the people Brothers has prescribed metformin for have noticed improvements in their blood sugars as well.

Brothers also prescribes a nighttime dose of metformin in cases where individuals have a difficult time managing overnight blood sugar surges (sometimes called the dawn phenomenon), caused by a glucose release from the liver. 

What the research says 

Experts we spoke to agreed that while they see many individuals who do well with metformin in the real world, scientific research is lacking. Metformin was originally studied in people with type 2 diabetes; there is much less data for use in those with type 1. However, a handful of smaller studies provide evidence of potential benefits for some people. 

While results are mixed, one study review noted the following positive effects of metformin for people with type 1 diabetes:

  • Reducing insulin needs (by 5-10 units per day) 
  • Lowering A1C (by 0.6-0.9%) 
  • Weight loss (from 3-13 pounds)
  • Lowering total cholesterol (by 11-16 mg/dL) 

Researchers concluded that overall, metformin was linked to lower insulin requirements, but not lower blood sugars. 

The largest single study on the topic tracked 428 adults with type 1 diabetes (average age 56) who had an elevated risk for heart disease. Researchers gave half the participants metformin and the other half a placebo and followed them over three years. They found that metformin slightly lowered body weight, LDL cholesterol (“bad” cholesterol), and insulin use. However, the biggest takeaway was the potential heart health benefits. Metformin was found to reduce the progression of atherosclerosis, a build-up of plaque in the arteries that can lead to heart disease.

Whether we see more research on metformin for type 1 diabetes is unclear as conducting large, long-term studies that could provide more solid data is expensive, Chang explained. Since metformin is available in a generic form, which makes it less profitable, there is less incentive for drugmakers to invest in this kind of research, she added.

The downsides of metformin

Overall, metformin can be a useful tool for some people struggling with insulin resistance and excess weight, but it’s not for everyone. 

“There's just not enough [evidence] for me to say that I would prescribe metformin to every patient with type 1 diabetes,” Brothers said. 

Metformin has a long track record as a very safe medication. But like any drug, it comes with potential downsides. For instance, it may increase your risk of low blood sugar. Some people experience side effects like an upset stomach, nausea, and vomiting. Studies also show that metformin causes a vitamin B12 deficiency for some individuals (an issue that those with type 1 diabetes are already at risk for). 

If you’re curious about metformin for type 1 diabetes

Keep in mind that diabetes health basics come first. Chang recommends prioritizing key health habits that can naturally boost insulin sensitivity and help you lose excess weight. That includes eating a nutritious diet, regularly exercising, getting enough sleep, and managing stress. 

Again, generally speaking, the best candidates for metformin are people who are experiencing serious insulin resistance and have excess weight. If you’re not sure if you’re experiencing insulin resistance, one sign is that your insulin needs have increased significantly.

“If you’re noticing that your insulin needs are going up in addition to your weight, it's worth a discussion with your endocrinologist,” Brothers said. “To me, there's little risk and potentially a great benefit.”

If you’re unsure how to broach the subject, Chang recommends asking your healthcare provider: “Do you think a medication like metformin would be helpful in my case?” Then you can discuss it together and figure out what makes sense for you. 

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