Should women with gestational diabetes be screened at delivery hospitalization for type 2 diabetes?

Background: Less than one-half of women with gestational diabetes mellitus are screened for type 2 diabetes postpartum. Other approaches to postpartum screening need to be evaluated, including the role of screening during the delivery hospitalization.

Objective: To assess the performance of an oral glucose tolerance test administered during the delivery hospitalization compared with the oral glucose tolerance test administered at a 4- to 12-week postpartum visit.

Study Design: We conducted a combined analysis of patient-level data from 4 centers (6 clinical sites) assessing the utility of an immediate postpartum 75-g oral glucose tolerance test during the delivery hospitalization (PP1) for the diagnosis of type 2 diabetes compared with a routine 4- to 12-week postpartum oral glucose tolerance test (PP2). Eligible women underwent a 75-g oral glucose tolerance test at both PP1 and PP2. Sensitivity, specificity, and negative and positive predictive values of the PP1 test were estimated for diagnosis of type 2 diabetes, impaired fasting glucose, or impaired glucose tolerance.

Results: In total, 319 women completed a PP1 screening, with 152 (47.6%) lost to follow-up for the PP2 oral glucose tolerance test. None of the women with a normal PP1 oral glucose tolerance test (n=73) later tested as having type 2 diabetes at PP2. Overall, 12.6% of subjects (n=21) had a change from normal to impaired fasting glucose/impaired glucose tolerance or a change from impaired fasting glucose/impaired glucose tolerance to type 2 diabetes. The PP1 oral glucose tolerance test had 50% sensitivity (11.8-88.2), 95.7% specificity (91.3-98.2%) with a 98.1% (94.5-99.6%) negative predictive value and a 30% (95% confidence interval, 6.7-65.3) positive predictive value for type 2 diabetes vs normal/impaired fasting glucose/impaired glucose tolerance result. The negative predictive value of having type 2 diabetes at PP2 compared with a normal oral glucose tolerance test (excluding impaired fasting glucose/impaired glucose tolerance) at PP1 was 100% (95% confidence interval, 93.5-100) with a specificity of 96.5% (95% confidence interval, 87.9-99.6).

Conclusion: A normal oral glucose tolerance test during the delivery hospitalization appears to exclude postpartum type 2 diabetes mellitus. However, the results of the immediate postpartum oral glucose tolerance test were mixed when including impaired fasting glucose or impaired glucose tolerance. As a majority of women do not return for postpartum diabetic screening, an oral glucose tolerance test during the delivery hospitalization may be of use in certain circumstances in which postpartum follow-up is challenging and resources could be focused on women with an abnormal screening immediately after the delivery hospitalization.