Metformin Vs. Insulin in The Managment of Gestational Diabetes Mellitus

Abstract

Objective To examine the effectiveness & safety of Metformin vs. Insulin in the treatment of pregnancy complicated by gestational diabetes mellitus (GDM) .  Design Open –labelled prospective randomized controlled study .Setting Basra maternity and children( tertiary level) hospital in Basra city . Sample 121 women with GDM who did not attain normoglycemia with diet during the period between January-December/2018.  Method Women were randomized to two groups :treatment by Insulin n= 60 & by Metformin  n=61.Main outcome measure The efficacy &safety of the use of oral Metformin in controlling hyperglycemia among women suffering from uncontrolled GDM by diet only; as compared to Insulin. Result There were no significant differences in the incidence of neonatal morbidity nor mortality including  macrosomia (10 (20%) versus 8( 16%)) ,intra uterine growth restriction (2(3%) vs. 5(3%)),mean birth weight(gm)(3923±412 vs. 3426±632),perinatal mortality (0 in both groups),birth trauma (0(0%)vs. 1(2%)),congenital anomaly(2(3%) in each group),neonatal hypoglycemia (8(13%)vs9(15%)),neonatal hyperbilirubinemia (17(28%)vs. 19(32%),& apgar score in Min 1&Min2 (7±1vs 6±1 &8±1 vs. 9±1)in Metformin vs. Insulin group. There was a tendency to a higher rate of deliveries by caesarean section ( 23(38%)vs. 13(22%)) &more spontaneous labor (34(56)%vs. 21(35%)) in the metformin group ,but induction of labor nearly same in both groups(25(41%) vs29(48%)) . Still both groups have comparable other maternal complications apart from less chance of developing hypertension (2(3%)vs13(22%)),less hypoglycemic episodes(11 (18%)vs33 (55%)), more hyperglycaemic postprandial episodes (18(30%)vs7(12%) ) ,less weight gain throughout the pregnancy  ( 1.4±3.20 vs. 3.9 ±3.5)in Metformin group, in spite of comparable fasting blood glucose level in both groups(6.5±0.7 vs. 6.0±0.5) .  9 (15%) of the Metformin treated women were failed to obtain normoglycemia and so ; needed  supplemental Insulin to be added. Those women who failed to have controlled glycemic status by monotherapy and needed combined therapy, were more obese,(mean BMI=36.2±3.4 vs. 30.6±1.4 kg/m²), had higher fasting  blood glucose level (7.4 ±1.2 vs. 6.1±0.5 mmol/L) and needed medical treatment for GDM earlier in pregnancy (about 26±3.2 vs. 32±3.4 wks)& their newborns had higher incidence of macrosomia(3(33%)vs. 7(13.5%)) than women who were normoglycemic with monotherapy.Conclusion Metformin is  effective in the control of maternal hyperglycemia & prevention of fetal macrosomia &other feto- neonatal events , especially in non obese women developing GDM  in late pregnancy. Women with considerable obesity , high fasting blood glucose and those who need for early pharmacological treatment during pregnancy may better be treated by Insulin alone or as adjuvant to the Metformin .