Introduction of metformin for gestational diabetes mellitus in clinical practice: has it had an impact?

Objective: The aim of the study was to compare maternal and neonatal outcomes in women with gestational diabetes mellitus (GDM) treated with metformin in addition to the dietary and lifestyle advice versus those treated traditionally with dietary and lifestyle advice only. Study design: A retrospective study of singleton pregnancies in women with GDM delivered between January 2008 to June 2010 (n = 592) at the Jessop Wing, Royal Hallamshre Hospital, UK. Introduction of metformin in August 2008 led to two comparable groups, those women receiving metformin, lifestyle advice (including dietary advice) +/- supplementary insulin and those women receiving lifestyle advice (including dietary advice) +/- supplementary insulin. Two hundred and ninety three women were treated with metformin and lifestyle advice and remaining 299 with lifestyle advice only. Supplementary insulin was used in both the groups if needed. Outcomes were analyzed using the chi-squared and t-tests. Results: There were no significant differences in baseline maternal characteristics between the two groups. Metformin was tolerated throughout the pregnancy by 90% of the women in the metformin + lifestyle advice group. Supplementary insulin was required by 21% in the metformin + lifestyle advice group compared to 37% in the lifestyle advice group (OR 0.46; 95% CI 0.32-0.66). Women in the metformin group had a significantly lower incidence of macrosomia (birth weight > 4 kg) (8.2% vs. 14.3% (OR 0.56; 95% CI 0.33-0.99)), as well as birth weight >90th centile (14.8% vs. 23.7% (OR 0.56; 95% CI 0.37-0.85)). There were no significant differences in maternal outcome measures between the groups. No serious maternal or neonatal adverse events were observed with the use of metformin. Conclusion: Metformin is safe and effective in the treatment of GDM in our experience. It is well tolerated and reduces the requirement for supplementary insulin. Women treated with metformin had a significantly lower incidence of macrosomic and large for gestational age neonates as well as a reduced caesarean section rate. (C) 2011 Elsevier Ireland Ltd. All rights reserved.