Therefore , although the overall effect of metformin on the concentration of serum Hcy was neutral , our results suggested that metformin could increase the concentration of Hcy when exogenous B-group vitamins or folic acid supplementation was not given
The aim of this systematic review is to assess whether metformin could change the concentration of serum homocysteine ( Hcy ) with and without simultaneous supplementation of B-group vitamins or folic acid .
Vitamin B12 and homocysteine status during pregnancy in the metformin in gestational diabetes trial: responses to maternal metformin compared with insulin treatment.
AIM The aim of the study is to compare the effects of metformin and insulin treatment for gestational diabetes mellitus ( GDM ) on vitamin B12 and homocysteine ( Hcy ) status . METHODS Women with GDM , who met criteria for insulin treatment , were r and omly assigned to metformin ( n = 89 ) or insulin ( n = 91 ) in the Adelaide cohort of the metformin in gestational diabetes ( MiG ) trial .  Fasting serum total vitamin B12 ( TB12 ) , holotranscobalamin ( HoloTC ) , a marker of functional B12 status and plasma Hcy concentrations were measured at 20 - 34 weeks ( at r and omization ) and 36 weeks gestation , then at 6 - 8 weeks postpartum . RESULTS Circulating TB12 , HoloTC and Hcy were similar in both treatment groups at each time point . Women who were taking dietary folate supplements  at r and omization had higher serum TB12 and HoloTC at r and omization than those not taking folate . Overall , serum TB12 fell more between r and omization and 36 weeks gestation in the metformin group than in the insulin group ( metformin : -19.7 ± 4.7 pmol/l , insulin : -6.4 ± 3.6 pmol/l , p = 0.004 ) . The decrease in serum TB12 during treatment was greater with increasing treatment duration in metformin-treated ( p < 0.001 ) , but not in insulin-treated women . CONCLUSIONS Total , but not bioavailable , vitamin B12 stores were depleted during pregnancy to a greater extent in metformin-treated  than in insulin-treated women with GDM , but neither analyte differed between groups at any stage . This adds further evidence supporting metformin as a safe alternative treatment to insulin in GDM . Further investigation is needed to evaluate whether women treated with metformin for longer periods in pregnancy require additional B12 or other supplementation
Therefore , although the overall effect of metformin on the concentration of serum Hcy was neutral , our results suggested that metformin could increase the concentration of Hcy when exogenous B-group vitamins or folic acid supplementation was not given
The aim of this systematic review is to assess whether metformin could change the concentration of serum homocysteine ( Hcy ) with and without simultaneous supplementation of B-group vitamins or folic acid .