Postpartum glucose intolerance following early gestational diabetes mellitus

Background: Patients with gestational diabetes mellitus are at increased risk for type 2 diabetes mellitus or glucose intolerance postpartum compared with those without diabetes mellitus.

Objective: We aimed to evaluate the association between early gestational diabetes mellitus and postpartum dysglycemia compared with gestational diabetes mellitus diagnosed by routine screening in a cohort of patients with obesity.

Study design: This was a secondary analysis of a randomized controlled trial of patients with obesity and singleton, nonanomalous gestations that compared early gestational diabetes mellitus screening at 14 to 20 weeks of gestation with routine screening at 24 to 28 weeks of gestation. Patients were included in this analysis if they were diagnosed with gestational diabetes mellitus at the primary study site. The primary outcome was postpartum dysglycemia, defined as any abnormality on 2-hour oral glucose tolerance test 6 weeks postpartum or clinical diagnosis based on hyperglycemia requiring pharmacotherapy after delivery with deferred glucose tolerance test. Maternal characteristics and outcomes were compared in bivariable analysis, and logistic regression estimated the association between early gestational diabetes mellitus and postpartum dysglycemia.

Results: Of 119 patients included in this analysis, 30 were diagnosed by screening at <20 weeks of gestation and 89 at 24 to 28 weeks of gestation. Patients were overall similar in baseline characteristics. Patients with early gestational diabetes mellitus were more likely to have postpartum dysglycemia than those with gestational diabetes mellitus diagnosed with routine screening (36.7% vs 14.6%; odds ratio, 3.38; 95% confidence interval, 1.31-8.73). Most patients with early gestational diabetes mellitus who had postpartum dysglycemia were diagnosed clinically (n=7/11), whereas none of the patients with gestational diabetes mellitus established by routine testing were diagnosed with postpartum dysglycemia clinically. All (100%) patients with early gestational diabetes mellitus who completed a postpartum glucose tolerance test had dysglycemia compared with only 45% of patients with gestational diabetes mellitus diagnosed on routine screening. The proportion of patients who followed up for postpartum visits and the timing of follow-up were similar between groups. Postpartum glucose tolerance test completion was low but also similar between groups.

Conclusion: Although postpartum glucose tolerance test completion is low, patients with gestational diabetes mellitus before 20 weeks of gestation, seem to be at higher risk for postpartum dysglycemia than those with gestational diabetes mellitus diagnosed at routine screening in a cohort of patients with obesity. Larger studies are needed to confirm these findings, but postpartum follow-up and diabetes mellitus testing may be even more important to improve long-term health in patients with early gestational diabetes mellitus.