Breastfeeding for at least 2 months was associated with decreased incidence of type 2 diabetes among women with gestational diabetes, new study results published in Annals of Internal Medicine suggest.
Gestational diabetes affects 5% to 9% of pregnancies in the United States, and increases the risk for type 2 diabetes. Lactation improves glucose and lipid metabolism, increases insulin sensitivity, and has favorable metabolic effects that could help women prevent postpartum diabetes, according to background information in the study.
“Breastfeeding promotion may be a practical, low-cost intervention during the postpartum period to prevent diabetes in high-risk women, with the potential benefits that are complementary to lifestyle interventions targeting weight loss,” the researchers wrote. “Modification of lactation behaviors to increase intensity and duration should be considered a high priority for pregnant and postpartum women with [gestational diabetes] because of their lasting metabolic benefits.”
The participants included women diagnosed with gestational diabetes who enrolled in the Study of Women, Infant Feeding, and Type 2 Diabetes After Gestational Diabetes Mellitus Pregnancy between 2008 and 2011.
The researchers conducted 3 in-person research examinations from 6 to 9 weeks after delivery, with annual follow-up for 2 years. The participants underwent an oral glucose tolerance test and researchers obtained blood samples at each examination. Participants also filled out questionnaires to assess diet quality and exercise.
Researchers determined lactation intensity through monthly questionnaires and telephone calls. The women were classified into 1 of 4 lactation intensity groups at 6 to 9 weeks after delivery, which included the exclusive lactation group (no formula, foods, or liquids), mostly lactation (>0 oz- 6 oz formula per 24 hours), mostly formula (>17 oz per 24 hours) and mixed (7oz-17 oz formula per 24 hours), or the exclusive formula group (breastfeeding <3 weeks).
Of 1010 women without diabetes at the beginning of the study, 11.8% developed incident diabetes within a 2-year follow-up period. The hazard ratios (HRs) for mixed or mostly formula, mostly lactation, and exclusive lactation groups compared with exclusive formula feeding were 0.64, 0.54, and 0.46, respectively (P for trend=.016).
The researchers also categorized durations of breastfeeding into groups of 2 to 5 months, longer than 5 to 10 months, and longer than 10 months and compared them with durations less than 2 months. HRs were 0.55, 0.50, and 0.43, respectively.
The data showed an overall 36% to 57% reduction in the 2-year diabetes incidence with higher intensity of lactation at 6 to 9 weeks after delivery and for periods longer than 2 months. The researchers noted that the association between lactation and the progression of type 2 diabetes could include the preservation of pancreatic cells, less inflammation, and improved endothelial function. They suggested further promotion to increase awareness on the issue.
“Greater allocation of healthcare resources to promote and support exclusive and extended breastfeeding may benefit high-risk women by reducing their risk for midlife progression to [diabetes],” the researchers concluded.