(HealthDay News) – Metformin does not reduce the occurrence of gestational diabetes (GD) among pregnant women with polycystic ovarian syndrome (PCOS) treated with metformin throughout pregnancy, according to a small study published in the June issue of Diabetes Care.

Daniela Romualdi, PhD, from Università Cattolica del Sacro Cuore in Rome, and colleagues enrolled 60 women with PCOS who conceived while being treated with metformin. At each trimester of ongoing pregnancies (47) an oral glucose tolerance test and a euglycemic-hyperinsulinemic clamp were performed.

The researchers found that 22 participants developed GD despite treatment. Insulin sensitivity was comparable at baseline between women who developed GD and women who did not. Independent of the trimester of GD diagnosis, there was a progressive decline in insulin sensitivity in all subjects. In patients with an early failure of metformin treatment, insulin secretion was significantly higher during the first trimester. There was a significant increase in insulin output as gestation proceeded for women with GD in the third trimester and women with no GD. All newborns were healthy and there was only one case of macrosomia.

“Women with PCOS who enter pregnancy in a condition of severe hyperinsulinemia have development of GD earlier, independently of metformin treatment,” the authors write.

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