New Study: Metformin Does Not Reduce Insulin Resistance in Type 1 Diabetes

Insulin resistance—a condition where the body does not respond effectively to insulin—is often thought of as a type 2 diabetes problem. However, researchers have increasingly recognized that many adults with type 1 diabetes also experience insulin resistance, which can raise their risk for heart disease and other cardiovascular complications.

In this new study, researchers compared insulin resistance in adults with type 1 diabetes to those without diabetes. They used a precise measurement called a hyperinsulinemic-euglycemic clamp, which directly measures how well the body uses insulin. The findings were striking: adults with type 1 diabetes showed significant insulin resistance in three areas—the liver (64% higher), muscles (29% lower glucose uptake), and fat tissue (higher fatty acid levels).

Given that metformin is widely used to treat insulin resistance in type 2 diabetes, researchers wanted to know whether it might help adults with type 1 diabetes. They conducted a randomized, placebo-controlled trial involving 40 adults with type 1 diabetes. Half received metformin at a dose of 1500 mg daily, and half received a placebo. The study lasted 26 weeks.

The primary goal was to see whether metformin would reduce the amount of glucose the liver produces on its own—a key marker of hepatic insulin resistance. After 26 weeks, the results were clear: metformin and placebo produced virtually identical outcomes. There was no meaningful difference between the groups, and the study did not support using metformin for this purpose.

Importantly, neither group experienced an increase in hypoglycemia (low blood sugar) or diabetic ketoacidosis, suggesting that metformin was safe in this population, at least over the study period.

This study adds important evidence to the treatment landscape for type 1 diabetes. While metformin remains valuable for people with type 2 diabetes and insulin resistance, these findings suggest it is not an effective tool for addressing the specific forms of insulin resistance that occur in type 1 diabetes.

The results highlight that type 1 and type 2 diabetes, despite some overlapping features, are distinct conditions requiring different approaches. Recognizing and managing insulin resistance in type 1 diabetes remains an important cardiovascular health goal—but metformin does not appear to be the answer, based on this evidence.

Researchers continue to investigate other ways to identify, measure, and address insulin resistance in people with type 1 diabetes. Anyone with questions about their own cardiovascular risk or treatment options should discuss this study with their diabetes care team.

Origin: nature.com (News report). Evidence: News report, corroborated with 1 indexed study. Type1Cure is an information and intelligence hub, not a medical advice service. This article summarizes published research and does not provide diagnosis, treatment, or personal medical guidance. Always talk to your own care team before changing anything about your Type 1 diabetes management.