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.
Risk/Benefit Ratio for Alcohol Includes Many Factors
“There is a relative paucity of data regarding women’s long-term health as it may relate to pregnancy and pregnancy outcomes,” Angela Bianco, MD, of Mount Sinai Hospital, New York, said in an interview.
Bianco said she was surprised by some of the study findings.
“Generally speaking, I consider alcohol to be of little to no nutritional value, and to have a high sugar content/glycemic index,” she said. “However, a reduced incidence of adult-onset diabetes has been observed among moderate drinkers in other large prospective studies as well,” she noted. “In contrast, some studies have shown an increased risk of diabetes among a proportion of subjects in the top alcohol consumption category, while other studies have found no association. Possible inconsistencies may be due to differences in drinking patterns and the types of beverages consumed,” Bianco explained.
A key point for clinicians to keep in mind is that “the study may be flawed based on the different criteria used to make a diagnosis of history of gestational diabetes, the fact that they excluded patients that did not return the questionnaires, and the fact that respondents may not have answered correctly due to recall bias” or other reasons, Bianco said. “Additionally, those who responded obviously had access to health care, which in and of itself is a confounder,” she noted.
Another key point is that “the effect of alcohol being consumed with or without a meal was not examined,” said Bianco. “Alcohol concentration is reduced if consumed with meals. Alcohol can lead to hypoglycemia (from reduced gluconeogenesis) during fasting states, but after meals (postprandial states) it can result in lower glucose disposal and higher blood glucose levels,” she said. “The available literature suggests that alcohol may improve insulin sensitivity and reduce resistance, but there is likely a U-shaped association between alcohol consumption and the risk of diabetes,” Bianco noted. “There is likely a delicate balance between benefits and risks of alcohol intake. The inherent benefit/risk ratio must take into account with other potential comorbidities including BMI, activity level, stress, and preexisting conditions,” she said.
“Additional long-term studies engaging patients with diverse ethnic and socioeconomic backgrounds with detailed information regarding the role of nutrition, alcohol intake, tobacco and drug use, environmental exposures, and medical comorbidities need to be performed,” Bianco concluded.
The study was supported by the Eunice Kennedy Shriver National Institute of Child Health and Human Development, the National Institute of General Medical Sciences, and the National Institute of Diabetes and Digestive and Kidney Diseases; the Nurses‘ Health Study II was supported by the National Institutes of Health. Lead author Hinkle and coauthor Cuilin Zhang, MD, are employees of the U.S. federal government. The researchers and Bianco had no financial conflicts to disclose.
This article originally appeared on MDedge.com, part of the Medscape Professional Network.
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