Among women with a history of gestational diabetes, alcohol intake of half a drink to one drink daily was associated with a 55% lower risk for subsequent type 2 diabetes, based on data from approximately 4,700 women in the Nurses’ Health Study II cohort.
However, the findings must be considered in the context of other risks and benefits of alcohol consumption before making statements or clinical recommendations, wrote Stefanie N. Hinkle, PhD, of the National Institutes of Health, Bethesda, Md., and colleagues.
Women with a history of gestational diabetes remain at increased risk for developing type 2 diabetes, so modifiable diet and lifestyle factors deserve further study, the researchers noted. Previous research has shown an association between light to moderate alcohol consumption and reduced risk of type 2 diabetes among women in the general population, but data on a similar risk reduction for women with a history of gestational diabetes are lacking, they added.
In a study published in JAMA Network Open, the researchers reviewed data from 4,740 women enrolled in the Nurses’ Health Study II who reported a history of gestational diabetes. These women were followed from Jan. 1, 1991, to Dec. 31, 2017, as part of the Diabetes & Women’s Health Study; dietary intake, including alcohol intake, was assessed every 4 years via validated food frequency questionnaires.
The average age at baseline was 38 years, and the median follow-up time was 24 years, yielding a total of 78,328 person-years of follow-up. Alcohol consumption was divided into four categories: none; 0.1 g/day to 4.9 g/day; 5.0 to 14.9 g/day, and 15.0 g/day or higher.
A total of 897 incident cases of type 2 diabetes were reported during the study period. After adjustment for multiple dietary and lifestyle variables, including diet and physical activity, only alcohol consumption of 5.0-14.9 g/day (approximately half a drink to one drink) was associated with a significantly decreased risk for incident type 2 diabetes (hazard ratio, 0.45) compared with women who reported no alcohol consumption.
On further adjustment for body mass index, women who reported alcohol consumption in the 5.0-14.9 g/day range had a 41% lower risk for developing incident type 2 diabetes (HR, 0.59); alcohol consumption in the other ranges remained unassociated with type 2 diabetes risk, although the researchers noted that these estimates were attenuated.
The median daily intake for women who consumed alcohol was 2.3 g/day, approximately one drink per week. Beer was the most frequently consumed type of alcohol.
When the researchers analyzed the data by alcohol type, notably, “only beer consumption of 1 or more servings a week was associated with a lower risk for type 2 diabetes,” although previous studies have suggested a stronger association in diabetes risk reduction with wine consumption vs. beer, the researchers noted.
The study findings were the potential for confounding factors not included in the adjustment, potential underreporting of alcohol intake, and potential screening bias toward women who were more health conscious, the researchers noted. Other limitations were lack of generalizability given that most of the study participants were white women, and a lack of data on binge drinking and whether alcohol was consumed with meals, they added. The study strengths included the prospective design, large size, long-term follow-up, and use of validated questionnaires, they said.
The researchers cautioned that the results should not be interpreted without considering other health outcomes. “Consistent with the 2020 Dietary Guidelines for Americans, which recommend that adults who do not consume alcohol do not initiate drinking, it may not be prudent for those with a history of gestational diabetes who do not consume alcohol to initiate drinking alcohol solely to reduce their risk for type 2 diabetes,” they emphasized.