Factors predicting early postpartum glucose intolerance in Japanese women with gestational diabetes mellitus: decision‐curve analysis

Aims To identify factors predicting early postpartum glucose intolerance in Japanese women with gestational diabetes mellitus, using decision‐curve analysis. Methods A retrospective cohort study was performed. The participants were 123 Japanese women with gestational diabetes who underwent 75‐g oral glucose tolerance tests at 8–12 weeks after delivery. They were divided into a glucose intolerance and a normal glucose tolerance group based on postpartum oral glucose tolerance test results. Analysis of the pregnancy oral glucose tolerance test results showed predictive factors for postpartum glucose intolerance. We also evaluated the clinical usefulness of the prediction model based on decision‐curve analysis. Results Of 123 women, 78 (63.4%) had normoglycaemia and 45 (36.6%) had glucose intolerance. Multivariable logistic regression analysis showed insulinogenic index/fasting immunoreactive insulin and summation of glucose levels, assessed during pregnancy oral glucose tolerance tests (total glucose), to be independent risk factors for postpartum glucose intolerance. Evaluating the regression models, the best discrimination (area under the curve 0.725) was obtained using the basic model (i.e. age, family history of diabetes, BMI ≥25 kg/m2 and use of insulin during pregnancy) plus insulinogenic index/fasting immunoreactive insulin