How breastfeeding lowers mothers' risk of developing type 2 diabetes

Studies have shown that breastfeeding offers protection against type 2 diabetes in mothers, but researchers have yet to pinpoint why. A new Yale study, led by Julie Hens, Ph.D., research scientist (endocrinology), has found a possible explanation.

The findings were presented at the Endo 2023 conference in Chicago in June.

In the study, researchers looked at changes in metabolism that are the result of breastfeeding. They found that mice that lactated after giving birth had an improvement in insulin sensitivity as well as an increase in the numbers of insulin-producing, pancreatic beta-cells compared with mice that did not lactate. Hens and her team believe this combination likely contributes to the protection against type 2 diabetes that breastfeeding provides.

"One of the triggers for the development of diabetes is the loss of beta-cells' ability to produce enough insulin to overcome insulin resistance—that is the inability of insulin to effectively lower blood sugar," she said, noting that genetics and obesity often cause insulin resistance, which becomes worse during pregnancy, especially in the third trimester.

Hens noted that while many people assume that nursing protects against diabetes by causing weight loss, the study suggests that the protective effects of breastfeeding in mice likely occur through multiple mechanisms that are independent of weight loss, which agrees with human studies.

Through her work, Hens hopes to spread the word that lactation is beneficial not just to the infant but also to the mother. "We want to make people aware that lactation can have a protective effect on a mother's metabolism," she said. "By defining the mechanisms involved in this protection against diabetes, we hope this research will lead to improved outcomes for women after childbirth as well as all patients with type 2 diabetes."