Lower risk of diabetes a benefit of breastfeeding
Results of a 30-year observational study show that breastfeeding is independently associated with lower incidence of diabetes. Published in JAMA Internal Medicine, the findings reflect outcomes in white and black women and document a 25% to 47% relative reduction in diabetes, depending on length of breastfeeding, which was unchanged by race, gestational diabetes (GD), or parity.
Some 1238 women (623 white; 615 black) from the Coronary Artery Risk Development in Young Adults (CARDA) study were included in the prospective cohort. All were aged 18 to 30 and did not have diabetes at baseline in 1985-1986. They all had at least 1 live birth after that, reported on how long they breastfed, and were screened for diabetes up to 7 times between 1986 and 2016.
Researchers examined the association between risk of development of diabetes and no breastfeeding and breastfeeding for up to 6 months, > 6 months to < 12 months, and 12 months or more. Outcomes were diabetes incidence rates per 1000 person-years and adjusted relative hazards (RH) with corresponding 95% confidence intervals (CI). Proportional hazards regression models were adjusted for biochemical, sociodemographic, and reproductive risk factors, family history of diabetes, lifestyle, and weight change during follow-up.
During 27,598 person-years, 182 incident diabetes cases were reported for an overall incidence rate of 6.6 cases per 1000 person-years (95% CI, 5.6-7.6). Rates for women with and without GD were 18.0 and 5.1, respectively (P for difference < .001). Duration of lactation was strongly and inversely associated with diabetes incidence, with RH from 0.75 for 0 to 6 months, to 0.52 for 6 months to < 12 months, to 0.53 for ≥ 12 months in comparison to no breastfeeding (P for trend = .01).
The authors said that their study provided longitudinal biochemical evidence that duration of lactation is independently associated with lower incidence of diabetes but the mechanism for that relationship requires further investigation.