Conference Coverage

Can insulin plus metformin improve pregnancy outcomes in women with type 2 diabetes?



– Insulin is the preferred agent for type 2 diabetes in pregnant women, yet about a third of pregnancies still have an adverse outcome, according Kim Boggess, MD, who spoke at the biennial meeting of the Diabetes in Pregnancy Study Group of North America.

“We are not where we need to be,” said Dr. Boggess, who is leading a trial that brings metformin, the first-line agent for type 2 diabetes outside of pregnancy, back into the picture for pregnant women – as an add-on to insulin.

It is an interesting twist, because pregnant women taking metformin for preexisting type 2 or gestational diabetes have been shown in some studies to require supplemental insulin, more than occasionally, to achieve target glycemic control.

This was the case in a small, randomized, controlled trial at Dr. Boggess’ institution, the University of North Carolina at Chapel Hill, in which 43% of pregnant women with type 2 diabetes who were assigned to metformin required supplemental insulin (Am J Perinatol. 2013;30[6]:483-90). The study also found, however, that women treated with metformin had significantly fewer episodes of hypoglycemia, compared with women using insulin (0% vs. 36%, respectively) and fewer reports of glucose values less than 60 mg/dL (7.1% vs. 50%).

“I don’t consider this [need for supplemental insulin] ‘metformin failure,’ because studies that use metformin as monotherapy and that [show some patients] ultimately requiring insulin support ... also show that these women need less insulin,” she said. “What’s the risk of insulin alone? Hypoglycemia. So using less insulin could be a good thing.”

Other research suggests there may be less maternal weight gain, less neonatal hypoglycemia, fewer neonatal complications, and improved maternal glycemic control in patients treated with metformin, alone or with add-on insulin, than with insulin alone. “We’re starting to get a sense in the literature that, at least in the [pregnant] population with type 2 diabetes, there may be a role for metformin,” said Dr. Boggess, professor and program director for maternal-fetal medicine at the university.

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