It’s not clear whether patients with type 2 diabetes gain any long-term benefit from taking the blood sugar-lowering drug metformin and insulin together rather than insulin alone.

That’s the conclusion of Danish researchers who reviewed data from 23 clinical trials involving more than 2,200 patients over the age of 18.

Reporting online April 19 in the BMJ, they found that taking metformin plus insulin leads to better blood sugar control, less weight gain and less need for insulin.

However, the researchers also noted that the clinical trials provided little information about long-term patient outcomes, such as the total numbers of deaths and deaths from cardiovascular disease.

This means that more clinical trials are needed to determine the long-term benefits and harms of the combination, specifically the risks of premature death.

The researchers, led by Bianca Hemmingsen of the Center for Clinical Intervention Research in Copenhagen, also believe that the combination of metformin and insulin raises the odds for severe low blood sugar (hypoglycemia), so further study is needed to assess the long-term benefits and harms of this regimen.

Currently, metformin is recommended in guidelines for type 2 diabetes patients starting on insulin.

One expert in the United States took issue with the findings.

“It certainly seems like a controversial statement since all our treatment is based on metformin with additional meds [insulin or otherwise] added when the blood sugar is no longer controlled and based on what an individual patient might need,” said Dr. Mary Ann Banerji, director of the Diabetes Treatment Center at the State University of New York Downstate Medical Center, in New York City.

She added that, “I am unaware that there is more hypoglycemia with metformin plus insulin compared to insulin alone, since presumably one would not be put on insulin unless it was needed and other modalities [treatments] tried.”

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(HealthDay News)