Effect of Metformin Added to Insulin on Glycemic Control Among Obese Adolescents with Type 1 Diabetes

Studies currently show that 24% of children and adolescents with Type 1 Diabetes are overweight and 15% are obese. The need for high doses of insulin may further promote weight gain. Additionally, insulin resistance has been associated with increased risk for cardiovascular risk factors. Metformin lowers glucose and was associated with low insulin doses without having an effect on A1C.

A trial was conducted using patients aged 12 to 19 diagnosed with Type 1 Diabetes for at least one year who had an insulin pump or administered at least 3 injections of insulin each day. The patients had an A1C between 7.5% and 9.9% and were in the 85th percentile for BMI. The patients were given 500 mg of metformin that was titrated over 4 weeks to reach 2000mg daily. The rest of the patients were given a placebo.

The baseline A1C was 8.8% in each both groups. At 13 weeks, the mean change in the metformin group was -0.2% and 0.1% in the placebo group. However at 26 weeks, the mean change in the metformin group was 0% and 0.3% in the placebo group. There was no significant difference for glycemic control. However, the patients in the metformin group used less insulin throughout the 26 weeks than the patients on the placebo and more patients in the metformin group maintained or lost weight.

In conclusion, metformin did not improve glycemic control in children or adolescents with Type 1 Diabetes. A few outcomes were favored but not significantly. Additionally, taking metformin increases the risk of GI adverse effects. Therefore, it is not indicated to prescribe metformin to this patient population.

This is interesting because many people do not fully understand the difference between Type 1 and Type 2 Diabetes and the medications to treat each. It is important to know what medications are indicated for each to educate children and parents. Thoughts on another oral medication that may be better suited for this patient population?

JAMA. 2015;314(21):2241-2250. 

1 thought on “Effect of Metformin Added to Insulin on Glycemic Control Among Obese Adolescents with Type 1 Diabetes”

  1. This study is interesting because it is testing whether an established medication can be used for something other than it’s directly implicated uses. Because type 1 and type 2 diabetes are very different in their physiologic functions and therapeutic needs, it was interesting to see the use of metformin in trying to reduce endpoints associated with type 1 diabetes. I agree with your recommendation that the risks do not outweigh the marginal benefits in this particular situation.

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