Introduction
The use of metformin in the management of gestational diabetes mellitus (GDM) is increasing in Australia. After failing lifestyle therapy, women are often given the initial choice of metformin or insulin. We explore the characteristics of women who choose metformin compared to women who choose insulin therapy in a culturally and linguistically diverse population in Sydney, Australia
Objective
To investigate patient factors in the choice of metformin or insulin in gestational diabetes
Method
We conducted a retrospective study of singleton pregnancies delivered between 2016-2018 at Liverpool Hospital, Sydney, Australia that were complicated by gestational diabetes and who were unable to be managed on medical nutritional therapy alone. The women were given the choice of either metformin or insulin as initial pharmacologic management. Characteristics and pregnancy outcomes of each group were analysed using Chi-square and T-test.
Results
Six hundred and eighty-two women initially chose insulin compared to 263 who chose metformin. Of the 263 women who chose metformin, 75% (n=193) of them were younger than 35 years of age compared to 64% (n=432) of the insulin group (p<0.0001). In addition, women who chose insulin were more likely to have had GDM in the past (32.2% compared to 23.6%, p=0.01) and/or prior exposure to insulin therapy (20.5% compared to 9.1%, p<0.0001). There were no significant differences in the body mass index, ethnicity, gestational weight gain and pregnancy outcomes between the two groups. In particular, the risk of birthweight below 2000g was not significant between metformin or insulin (0.6%compared to 2.2%, p=0.561).
Conclusion
This study reflects real life clinical practice where women were given a choice in managing their gestational diabetes. The study helps characterise the women who are more likely to choose one therapy over the other with the metformin group more likely to be younger with no prior history of GDM or exposure to insulin administration. There were no significant differences in pregnancy outcomes between metformin or insulin, and the risk of birthweight below 2000gwas not significantly different between the 2 groups.