Persistence of Risk for Type 2 Diabetes After Gestational Diabetes Mellitus

Objective: Gestational diabetes complicates about 6% of pregnancies and strongly predicts subsequent type 2 diabetes. It has not been fully elucidated how risk depends on the number of affected pregnancies or how long the excess risk persists.

Research designs and methods: We assessed reproductive histories in relation to risk of type 2 diabetes, using a nationwide cohort of 50,884 women. Among initially nondiabetic participants, 3,370 were diagnosed with diabetes during 10 years of follow up. We used Cox proportional hazards models that allowed risk to depend on age, cumulative number of pregnancies with gestational diabetes, and time since the most recent affected pregnancy, adjusting for body mass index, educational level, and race/ethnicity.

Results: History of one or more pregnancies with gestational diabetes predicted elevated age-specific risk of type 2 diabetes, with a hazard ratio of 3.87 (95%CI: 2.60-5.75) 6-15 years after an affected pregnancy. Risk increased steeply with multiple affected pregnancies. The age-specific associations attenuated over time after an affected pregnancy, with an estimated 24% reduction of the hazard ratio per decade. Risk remained elevated, however, for more than 35 years.

Conclusions: Gestational diabetes predicted markedly increased rates of type 2 diabetes. Relative risk increased substantially with each additional affected pregnancy. The estimated hazard ratio declined with time after a gestational diabetes pregnancy, but remained elevated for more than 35 years. Women recalling a history of gestational diabetes should be screened regularly for type 2 diabetes, even late in life