Short-term antidiabetic treatment with insulin or metformin has a similar impact on the components of metabolic syndrome in women with gestational diabetes mellitus requiring antidiabetic agents: results of a prospective, randomised study.

Gestational diabetes mellitus (GDM) is associated with an increased prevalence of fetal and maternal complications primarily caused by maternal hyperglycemia, which results in abnormal fetal growth. Diet modification is a common first step in the treatment of GDM, followed by antidiabetic pharmacotherapy if this approach fails. Insulin therapy is generally accepted; however, oral hypoglycemic agents have been used in this population. In this prospective, randomised study, we compared maternal metabolic status after treatment with insulin or metformin. Pregnant women (gestational age: ≥ 20 weeks) with GDM requiring medical hypoglycemic treatment were randomly allocated to the Metformin (n = 35) or Insulin (n = 43) Groups. Maternal metabolic status - assessed by glycated hemoglobin (HBA1c) level, glycemic profile, insulin concentration, Homeostatic Model Assessment - Insulin Resistance index, and lipids - was recorded at booking and throughout pregnancy. The characteristics of the study group were: maternal age 33.5 ± 5.9 years, gestational age at baseline 28.5 ± 3.5 weeks, prepregnancy body mass index (BMI) 32.2 ± 3.5 kg/m(2), HbA1c at baseline 5.6 ± 0.6%, and average daily glycemia 5.9 ± 0.6 mmol/dl. Fasting glycemia at term was significantly lower in the Insulin Group but there were no significant differences in mean daily glycemia, HbA1c and BMI at term between the groups. Longitudinally, there was a small but significant increase in BMI and a significant increase in high-density lipoprotein-cholesterol in the Insulin Group and a significant increase in the atherogenic index of plasma (AIP) and a trend towards higher triglycerides in the Metformin Group. Both fasting and average daily glycemia were significantly reduced following treatment in both groups. No such change was evident for HbA1c. In a relative risk analysis, metformin treatment was associated with an insignificant elevated risk of HbA1c, triglycerides and lipid indices falling within the highest quartile at term. The risk of gestational weight gain and total cholesterol falling within the highest quartile at term was insignificantly reduced in the Metformin Group. In conclusion, short-term antidiabetic treatment with insulin or metformin has a similar impact on markers of metabolic syndrome in women with GDM requiring antidiabetic treatment. Secondly, treatment with metformin is associated with increased triglyceride levels and higher AIP in the third trimester in pregnant women with GDM.