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

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.

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.

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.

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).

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.