A new study finds that giving metformin to overweight adolescents with type 1 diabetes alongside insulin does not improve blood glucose control.

According to Dr. Sanjoy Dutta, PhD, Juvenile Diabetes Research Federation (JDRF) – which supported the study – glucose management is at its worst among obese and overweight adolescents with type 1 diabetes. This can require higher insulin doses, leading to further weight gain.

What is Metformin ?

Metformin is commonly used to treat type 2 diabetes, but this study investigated its effects on 140 type 1 diabetes adolescents who had a baseline HbA1c of 8.8 per cent (72.7 mmol/mol).

The study, which lasted for 26 weeks, was conducted across 26 pediatric clinics in the United States T1D Exchange Clinical Network between October 2013 and February 2014.

Patients randomly received metformin or placebo alongside their basal-bolus insulin regimen. After 26 weeks, the same mean change in HbA1c levels was observed in both groups.

However, 24 per cent of the metformin group had a 10 per cent reduction in Body Mass Index (BMI) from the beginning of the study. In the placebo group, this figure was seven per cent.

The metformin group also experienced lower mean total daily insulin doses compared to the placebo group at 26 weeks and throughout the duration of the study.

Dutta explained: “The reduction in body weight, or improved adiposity, as well as the significant reduction in insulin dose, are significant end points that will benefit patients in the long run.”

Study author Ingrid Libman, MD, PhD, associate professor at Children’s Hospital of Pittsburgh, Pennsylvania, added that the results of the study do not support the prescription of metformin to overweight type 1 adolescents.

Libman said: “Knowing that we were not able to show that metformin really had an effect on glycemic control, I would say that emphasizing compliance with diabetes management overall is imperative.”

Libman noted that current treatment options such as regularly blood glucose testing, getting regular physical activity and eating a healthy diet are essential for type 1 diabetes patients, especially those who are overweight.

The findings were published in the Journal of the American Medical Association.