Gestational diabetes mellitus: Who requires insulin therapy?

Background: The prevalence of gestational diabetes mellitus (GDM) is increasing in Australia. Management of GDM has taken up a significant share of the workload of diabetes services in public hospitals, especially in managing women who require insulin therapy. Aims and Methods: The aim of this study is to assess patient factors that predict failure of medical nutritional therapy (MNT) thus necessitating insulin therapy. A retrospective review of clinical characteristics of women with GDM who attended antenatal clinics at Liverpool Hospital between 2007 and 2009 was conducted. Results: Of the 612 women included in this study, 52.8% required insulin therapy. Women with GDM who required insulin therapy had greater body mass index (BMI), were more likely to have previous GDM, had higher fasting glucose level on 75-g oral glucose tolerance test (OGTT) and were diagnosed with GDM at an earlier stage of their pregnancy. On multivariate logistic regression analysis, BMI, fasting glucose level and 2-h glucose level on OGTT and gestational week when GDM was diagnosed were all independent predictors for requirement of insulin therapy. Offspring of women on insulin therapy had higher birth weight and birth-weight percentile than those of women on MNT, but there was no difference in neonatal morbidity. Conclusion: Women with GDM who require insulin therapy differ from those who can be managed on MNT alone. Being aware of factors that predict failure of MNT could help diabetes services develop a more efficient model of care in the management of women with GDM.