Science News

from research organizations

This cheap drug could help people with type 1 diabetes use less insulin

A cheap, 100-year-old drug could quietly reduce insulin needs in type 1 diabetes—and scientists are racing to figure out why.

Date:

April 15, 2026

Source:

Garvan Institute of Medical Research

Summary:

A surprising new clinical trial has revealed that metformin—a cheap, century-old drug widely used for type 2 diabetes—may help people with type 1 diabetes in an unexpected way. While researchers initially hoped it would reduce insulin resistance, they instead found it allows patients to use about 12% less insulin while maintaining stable blood sugar levels.

Facebook

Twitter

FULL STORY

A century-old diabetes drug may help people with type 1 diabetes use less insulin, even though it doesn’t improve insulin resistance as expected. Scientists are now exploring whether the gut microbiome holds the key to this unexpected effect. Credit: Shutterstock

A new clinical trial led by the Garvan Institute of Medical Research suggests that metformin, a widely used and inexpensive drug for type 2 diabetes, could help people with type 1 diabetes reduce how much insulin they need. The findings point to a potential new way to manage the condition more effectively.

For years, doctors have prescribed metformin to some people with type 1 diabetes in hopes of improving insulin resistance. That approach has mostly been based on limited evidence. Now, results from a controlled clinical trial show that while metformin does not improve insulin resistance in type 1 diabetes, it does help lower the amount of insulin required to keep blood sugar levels within a healthy range.

Published in Nature Communications, the study highlights a surprising benefit that could ease the daily challenges faced by people who rely on insulin therapy.

The Challenge of Managing Type 1 Diabetes

Type 1 diabetes is an autoimmune disease that affects more than 130,000 Australians. In this condition, the immune system attacks the insulin-producing cells in the pancreas. As a result, patients must take insulin for life to control their blood sugar.

Managing the disease can be demanding. People with type 1 diabetes make an estimated 180 additional daily decisions related to monitoring and adjusting their blood sugar levels.

Over time, some patients develop insulin resistance, meaning their bodies respond less effectively to insulin. This can lead to higher and higher doses being needed to maintain stable blood sugar.

"Insulin resistance is a growing problem in type 1 diabetes. Not only does it make regulating blood sugar levels difficult, but it is an underappreciated risk factor for heart disease, which is one of the biggest causes of health complications and deaths in those with type 1 diabetes," says Dr. Jennifer Snaith, endocrinologist and co-lead of the study.

Clinical Trial Tests Metformin in Type 1 Diabetes

To better understand whether metformin could help, researchers conducted the first randomized controlled trial of its kind in adults with type 1 diabetes. The study, known as the Insulin Resistance in Type 1 Diabetes Managed with Metformin (INTIMET) study, examined whether the drug could reduce insulin resistance in this group.

Metformin is commonly used to treat type 2 diabetes and is already prescribed off-label to as many as 13,000 Australians with type 1 diabetes. However, its exact effects in this population have remained unclear.

"We randomized 40 adults with long-term type 1 diabetes to take either metformin or a placebo for six months. We examined whether their insulin resistance changed over that time through a sophisticated and comprehensive research technique, called a clamp study, that allowed us to map insulin resistance in different parts of the body," explains Professor Greenfield.

Unexpected Results on Insulin Use

The results did not match expectations. Researchers found no improvement in insulin resistance and no significant changes in blood sugar levels among those taking metformin.

However, one key finding stood out. Participants who took metformin needed about 12% less insulin than those in the placebo group to maintain stable blood sugar.

"Although we didn't find changes to insulin resistance from the use of metformin, we did show that people taking it used around 12% less insulin than those on placebo. This is an important result. Insulin is a relatively old treatment which, while lifesaving, comes with significant mental and physical burden. This means that lowering the amount of insulin used is a priority for many people living with type 1 diabetes. We have shown that a very cheap, accessible medication may serve this purpose and this is very exciting," Dr. Snaith says.

Scientists Explore Possible Role of the Gut Microbiome

Researchers are now working to understand why metformin reduces insulin needs if it does not affect insulin resistance.

Professor Gre