GDM diagnosed earlier in pregnancy was associated with a higher risk of obesity in childhood. A prospective cohort study published in Diabetes Care evaluated the impact of diagnosis timing, treatment type, and glycemic target attainment on long-term obesity outcomes in children.

The study included 809 mothers with GDM treated with diet or glyburide who enrolled 6 to 9 weeks postpartum between 2008 and 2011. Mothers diagnosed with diabetes after delivery were excluded. Diagnosis timing was classified as early, before 24 weeks of gestation, or standard, at or after 24 weeks. Treatment type, achievement of self-monitored glycemic targets, and maternal prepregnancy body mass index (BMI) were obtained from electronic health records. Child height and weight were assessed between ages 5 and 11 years. Log-binomial regression models estimated adjusted relative risks (aRRs).

The cohort was multiethnic, with 77% identifying as Asian, Black, or Hispanic. Mean prepregnancy BMI was 29.4 kilograms per square meter. Early GDM diagnosis occurred in 20% of mothers. Glyburide treatment was used in 27%, and glycemic targets were met by 70%. At follow-up, 25% of children were classified as obese.

In joint analyses of diagnosis timing and treatment type, early GDM diagnosis was associated with higher childhood obesity risk. Compared with standard diagnosis and dietary treatment, the aRR was 1.58 (95% confidence interval [CI] 1.19-2.12) for early diagnosis with glyburide treatment and 1.53 (95% CI 1.15-2.04) for early diagnosis with dietary treatment.

These findings show that exposure to GDM diagnosed before 24 weeks is associated with increased obesity risk in childhood. This association was independent of treatment type, glycemic target attainment, and maternal prepregnancy BMI.