Association of Habitual Alcohol Consumption with Long-term Risk of Type 2 Diabetes among Women with a History of Gestational Diabetes

Importance: Women with gestational diabetes are at high risk for type 2 diabetes. Identifying modifiable dietary and lifestyle factors, such as alcohol intake, that can be useful in delaying or preventing progression to overt type 2 diabetes is of particular interest. Objective: To evaluate the association between alcohol consumption and risk for type 2 diabetes among women with a history of gestational diabetes. Design, Setting, and Participants: This cohort study included women from the Nurses' Health Study II cohort who reported a history of gestational diabetes and were followed up from January 1, 1991, to December 31, 2017, as part of the Diabetes & Women's Health Study. Data analysis was performed from 2020 to 2021. Exposures: Dietary intakes, including alcohol, were assessed every 4 years using validated food-frequency questionnaires. Main Outcomes and Measures: Multivariable Cox proportional hazards regression models were used to estimate hazard ratios (HRs) and 95% CIs for the association of alcohol intake with risk for incident type 2 diabetes after a pregnancy during which gestational diabetes was diagnosed. Results: A total of 4740 women were included in the study; the mean (SD) age at baseline was 38.2 (5.0) years, and the median follow-up time was 24 years (interquartile range, 18-28 years), resulting in 78328 person-years of follow-up. During this period, 897 incident cases of type 2 diabetes were reported. After adjustment for major dietary and lifestyle factors, compared with women who did not consume any alcohol, only alcohol consumption of 5.0 to 14.9 g/d was associated with decreased risk for incident type 2 diabetes (HR, 0.45; 95% CI, 0.33-0.61); there was no association of alcohol consumption of 0.1 to 4.9 g/d or 15.0 g/d or more (maximum, 74.2 g/d) with risk of type 2 diabetes (0.1 to 4.9 g/d: HR, 0.87 [95% CI, 0.73-1.03]; ≥15.0 g/d: HR, 0.62 [95% CI, 0.37-1.04]). After additional adjustment for body mass index, women who reported alcohol consumption of 5.0 to 14.9 g/d had a 41% lower risk for developing incident type 2 diabetes (HR, 0.59; 95% CI, 0.42-0.81); consumption of 0.1 to 4.9 g/d and consumption of 15.0 g/d or more were still not associated with risk of type 2 diabetes, but the results were attenuated (0.1-4.9 g/d: HR, 1.02 [95% CI, 0.85-1.23]; ≥15.0 g/d: HR, 0.75 [95% CI, 0.42-1.33]). Conclusions and Relevance: In this cohort study, among women with a history of gestational diabetes, usual alcohol intake of 5.0 to 14.9 g/d (approximately 0.5-1 drinks per day) was associated with a lower risk for type 2 diabetes. These findings should be interpreted in the context of other known risks and benefits of alcohol consumption when considering clinical recommendations for individual women with a history of gestational diabetes.