Women with gestational diabetes mellitus (GDM), breastfeeding reduced the risk of progressing to type 2 diabetes.
A team of investigators led by Erica Gunderson, PhD, a researcher at Kaiser Permanente in Oakland, Calif carried out a large prospective cohort study found that compared to women with GDM who used formula, those who exclusively breastfed were half as likely to be diagnosed with diabetes 2 years post-delivery.
Gunderson and colleagues mentioned in Annals of Internal Medicine –
“Previously published studies on the topic yielded conflicting results and did not control well for potential confounders and reverse causation. Women with a history of GDM are faced with an extremely high risk for type 2 diabetes; up to 50% diagnosed within 5 years after delivery. In our study, both higher lactation intensity and duration showed strong, graded protective associations with diabetes mellitus incidence, independent of risk factors.”
“The American Diabetes Association recommends that women with GDM breastfeed their babies. However, previous evidence was insufficient to conclude that breastfeeding protected women against type 2 diabetes,” Gunderson told MedPage Today via email.
This adds one more reason to plethora of already existing proven benefits of breastfeeding. Breastfeeding is likely to become the centerpiece of early diabetes prevention strategies during the postpartum period. There are women who are still unaware of the benefits of exclusive breastfeeding, although there have been many support groups and services, all advocating breastfeeding.
The study concludes with a message that breastfeeding promotion may be a practical, low-cost intervention during the postpartum period to prevent diabetes in high-risk women, with the potential for benefits that are complementary to lifestyle interventions targeting weight loss.
These findings will have major implications for health care systems to allocate greater resources for provision of breastfeeding education and support services to high-risk women with GDM so that they may breastfeed optimally and lower their risk.
The study included more than 1,000 women with GDM enrolled in the in the Study of Women, Infant Feeding, and Type 2 Diabetes After GDM Pregnancy (SWIFT) between 2008 and 2011. Approximately 75% of this cohort was Hispanic, Asian, or black.
According to MedPage Today, Feldman-Winter, who is also the policy chairperson for the section on breastfeeding at the American Academy of Pediatrics (AAP) said:
“It really drives home the message that we have to support the exclusivity of breast feeding, meaning helping mothers and families to avoid the temptation to introduce formula when it isn’t necessary,”
Research Study
The women were given oral glucose tolerance tests at baseline (6-9 weeks after delivery) and annually for 2 years. Approximately 12% of study participants developed type 2 diabetes during the 2-year follow up.
Gunderson and colleagues analyzed the relationship between how consistently and how long women breastfed and the risk for diabetes, controlling for potential confounders including ethnicity, education, prepregnancy body-mass index, GDM treatment strategy, oral glycose tolerance test scores, gestational age at GDM diagnosis, and subsequent births during the follow up.
Gunderson and colleagues found a graded inverse association between consistency of breastfeeding and hazard ratios for diabetes risk, with women exclusively feeding formula to their infants as the reference group (P=0.016 for trend):
Mostly formula feeding or inconsistent: HR 0.64; 95% CI 0.37-1.12
Mostly breastfeeding: HR 0.54; 95% CI 0.32-0.92
Exclusive breastfeeding: HR 0.46; 95% CI 0.24-0.88
The investigators found a similar relationship between duration of breastfeeding and diabetes risk, with breastfeeding ≤2 months as reference (P=0.007 for trend):
>2-5 months: HR 0.55; 95% CI 0.31-1.01
>5-10 months: HR 0.50; 95% CI 0.25-0.99
>10 months: HR 0.43; 95% CI 0.23-0.82
When Gunderson and colleagues also adjusted for weight change from delivery to 1 year, the relationships were slightly attenuated but still statistically significant.
“Our study found that differences in weight change within one year after delivery did not explain the lower risk of diabetes with higher lactation intensity and longer duration,” Gunderson said. “Breastfeeding may have biological effects on metabolism and cellular functions that can ‘reset’ the metabolism to the more favorable preconception state and aid recovery from pregnancy’s physiological adaptations. Scientists are only beginning to explore the potential mechanisms.”
The study adds to previous evidence in two important ways, said Lori Feldman-Winter, MD, a pediatrician at Cooper University Health Care in Camden, N.J. First, it demonstrates that breastfeeding is beneficial to all women with GDM, not just especially high-risk populations such as Native Americans in which previous studies were done. Second, it demonstrates the importance of breastfeeding exclusively.
For all women, the AAP recommends exclusive breastfeeding for about 6 months, followed by continued breastfeeding with complementary foods for 1 year or longer. However, in survey data, only 43% of U.S. women report exclusively breastfeeding at 3 months, and by 6 months only 51% are breastfeeding at all, Gunderson and colleagues noted.
