effect of metformin on diabetes mellitus prevention in pregnant women with risk factors

objective: this study evaluated the efficacy and safety of metformin on prevention of gestational diabetes mellitus in women with high risk of gdm. materials and methods: total number of 189 pregnant women aged between 25 to 35, and 10 to 14 weeks pregnancy,admitted to  mirza koochakkhan hospital, tehran in january 2008 - january 2009 entered to this randomized controlled clinical trial. the women had one of the three risk factors; history of gdm, family history of diabetes, or bmi ≥ 30 kg/m 2 , with normal results in the glucose challenge test (gct) or the glucose tolerance test (gtt). subjects were randomly split to two groups; 63 women (group a) who received metformin (500 mg, twice a day) and 126 women (group b) did not use metformin. incidence  of gestational diabetes was compared between two groups. results: the incidence  of gestational diabetes was significantly different between two groups (%1.4 in group a, %15.4 in group b) ( p <0.001). the study also showed that the insulin requirement was significantly different between two groups after developing gdm (group a %3.6, group b %9.5, p =0.001). conclusion: using metformin can effectively reduce the incidence of gdm in pregnant women at risk.