Spotlight on the use of metformin for type 1 diabetes

Metformin (e.g., Glucophage) is an oral medication that is widely used as a treatment for type 2 diabetes (T2D). It decreases the production of glucose in the liver and the absorption of glucose in the intestine in order to bring blood sugar levels within the target range. It is generally one of the first medications that are prescribed to people with this condition.   

Why is metformin so widely used?

Metformin offers many benefits. Not only does it lower blood sugar levels without increasing the risk of hypoglycemia, but it has also been shown to help decrease body mass index (BMI), increase insulin sensitivity, and lower cholesterol (LDL) levels.

But a number of adverse side effects of a gastrointestinal nature, such as nausea, abdominal pain and diarrhea, can limit its use, in spite of the benefits it can provide. 

Can it be used for type 1 diabetes?

If metformin is widely used in treating T2D, could it also help people with type 1 diabetes (T1D) to manage their blood sugar levels?

T2D is characterized by an insulin resistance that develops gradually over time and raises blood sugar levels. People with T1D can develop insulin resistance as well if their blood sugar levels are out of range in the long term. This condition is called double diabetes. Some healthcare professionals prescribe metformin to people with T1D who have developed insulin resistance, but its use is a little more complicated than it is for people with T2D.

A number of experts have also wondered whether metformin could be prescribed even to people with T1D who don’t have insulin resistance to help them manage their blood sugar. 

So far, studies seem to indicate that metformin doesn’t significantly improve HbA1c levels in people with T1D. A decrease of HbA1c levels was observed in one study after a three-month period, but only temporarily. However, other studies have shown that metformin can slightly lower cholesterol levels and reduce weight, increase insulin sensitivity and decrease the risk of heart disease. So, metformin can be safe and beneficial for people with T1D who are at risk for heart disease or take high doses of insulin.  

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  • Livingstone, R., Boyle, J.G., Petrie, J.R., et al. (2017). A new perspective on metformin therapy in type 1 diabetes. Diabetologia, 60, 1594–1600. https://doi.org/10.1007/s00125-017-4364-6
  • Meng, H., Zhang, A., Liang, Y., Hao, J., Zhang, X., Lu, J. (2018). Effect of metformin on glycaemic control in patients with type 1 diabetes: A meta-analysis of randomized controlled trials. Diabetes/Metabolism Research and Reviews, 34(4). doi:10.1002/dmrr.2983

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