Introduction
Gestational diabetes mellitus (GDM), defined as impaired glucose metabolism first identified in pregnancy, complicates an estimated 288,000 pregnancies in the United States annually.1,2Without intervention, an estimated 70% of women with GDM progress to type 2 diabetes within 10 years of delivery.3 Women with GDM are at higher risk for stroke, cardiovascular and liver disease during their lifetime.4-7 Current guidelines recommend that women with recent GDM receive an oral glucose tolerance test (OGTT) at 4-12 weeks postpartum and annually thereafter.8,9However, postpartum OGTT completion is less than 50%.10-13 Recently, an OGTT at 2 days postpartum, prior to women being discharged after delivery, was shown to have comparable predictive ability as an OGTT at 4-12 weeks postpartum, with superior completion rates.14 Despite this advance, the sensitivity and positive predictive value of an OGTT at either 2 days or 4-12 weeks postpartum to predict progression to impaired glucose tolerance post-partum remains at 50% or less. This leads to a missed opportunity to identify individuals after delivery most likely to develop type 2 diabetes over their life course.14
Predictive models have been used to develop clinical risk scores, such as the FINDRISC Diabetes Risk Score, to identify non-pregnant persons at high risk for progression to types 2 diabetes for follow-up and intervention.15-18 These risk scores do not account for glucose metabolism in pregnancy and therefore are not applicable to women with recent GDM. In women with GDM, age, body mass index (BMI), race/ ethnicity, family history of type 2 diabetes, and insulin treatment in pregnancy are all correlated with the risk of progressing to pre-diabetes and type 2 diabetes postpartum,1,19,20but have not been integrated into a clinically useful prediction model to identify high risk women at delivery.
To fill this gap, we developed a predictive model using clinical data available around the time of delivery to identify women with GDM in their most recent pregnancy who are at high risk for progression to impaired glucose tolerance by 1 year postpartum.