High pre-pregnancy BMI with a history of gestational diabetes mellitus is associated with an increased risk of type 2 diabetes in Korean women

Despite the importance of pre-pregnancy body mass index (BMI) and a history of gestational diabetes mellitus (GDM) in the progression of GDM to type 2 diabetes, few studies have evaluated the combined effect of high pre-pregnancy BMI and GDM status on the future development of type 2 diabetes in Korean women. This study aimed to examine the relationship of pre-pregnancy BMI and GDM history with the risk of type 2 diabetes among Korean women. In addition, the effects of pre-pregnancy BMI and current BMI on the risk of type 2 diabetes were evaluated. Women who gave birth in the Health Examinees Study of the Korean Genome and Epidemiology Study from 2004 to 2013 (n = 59,258) were included in this study. Multivariable logistic regression was used to examine the association of pre-pregnancy BMI categories (underweight: <18.5 kg/m(2); normal: 18.5–22.9 kg/m(2); overweight: 23.0–24.9 kg/m(2); obese: ≥25.0 kg/m(2)) and GDM history with the risk of type 2 diabetes after controlling for the following covariates: age, education, income, smoking status before the first pregnancy, alcohol consumption, regular exercise, menarche age, first pregnancy age, and first pregnancy outcome. Compared to women with normal pre-pregnancy BMIs, women with overweight and obese pre-pregnancy BMIs had higher odds of developing type 2 diabetes (adjusted odds ratio [AOR]: 1.13, 95% confidence interval [CI]: 1.02–1.25 and AOR: 1.29, 95% CI: 1.10–1.50, respectively) after controlling for covariates. Women with pre-pregnancy BMIs <23 kg/m(2) and current BMIs ≥23 kg/m(2) had increased odds of developing type 2 diabetes (AOR: 1.64, 95% CI: 1.51–1.78) compared to those with pre-pregnancy BMIs <23 kg/m(2) and current BMIs <23 kg/m(2). Among women without a history of GDM, those with overweight and obese pre-pregnancy BMIs had increased odds of developing type 2 diabetes compared to those with normal pre-pregnancy BMIs (AOR: 1.12, 95% CI: 1.01–1.24 and AOR: 1.23, 95% CI: 1.05–1.44, respectively). Among women with GDM, those with obese pre-pregnancy BMIs had increased odds of developing type 2 diabetes (AOR: 3.84, 95% CI: 1.52–9.87). This study showed that there was a higher likelihood of developing type 2 diabetes in women who were overweight or obese before pregnancy with a history of GDM compared to their counterparts without a history of GDM. Furthermore, high pre-pregnancy BMI or high current BMI increased the risk of type 2 diabetes in Korean women, regardless of GDM history. This emphasizes the importance of maintaining a healthy weight status before and after pregnancy to prevent the future risk of type 2 diabetes.