Breastfeeding may provide mothers with long-lasting protection against diabetes, according to a new study published in Diabetes.

Prior research suggests that breastfeeding protects women from developing Type 2 diabetes decades after their children have been weaned; however, the reasons behind this are unclear, according to the current study. 

One theory is that breastfeeding changes how the body uses insulin. Metabolic studies have found that although pregnancy reduces the body’s sensitivity to insulin, lactation may restore it, according to the researchers. 

The study authors investigated this hypothesis by recruiting 18 women who had recently given birth. Twelve of the women were breastfeeding or giving their babies less than 6 ounces of formula per day and the other 6 were exclusively formula feeding. 

At 5 weeks postpartum, the volunteers came to the University of Texas (UT) Southwestern for a comprehensive medical exam. The next week, the women returned for a hyperinsulinemic-euglycemic clamp, which is a test that measures insulin sensitivity. 

At that visit, they also received stable isotopes during the test. These are tracers that measure insulin activity for organs of interest, such as the liver. At 8 weeks postpartum, the participants underwent magnetic resonance spectroscopy, which measures the amount of fat in their livers. 

The study showed that all women had low blood insulin concentrations that is typical in the postpartum period, no matter what they were feeding their babies. Even with these low levels, after a 12-hour fast, the lactating mothers produced 2.6-fold more glucose and released 2.3-fold more fatty acids stored in their fat tissue compared with mothers who were formula feeding. 

The results from the tests found that breastfeeding increases insulin sensitivity to highly insulin-sensitive organs. 

"Lactation is millions of years old, but we still have a long way to go before we understand all there is to learn…If we know better how it happens in the body, we can help improve the health of women and children,” Maria A. Ramos-Roman, MD, associate professor of internal medicine in the division of endocrinology at UT Southwestern, said in the press release.

The changes in insulin levels observed may explain the legacy benefits found in other epidemiologic studies, which could offer a buffer against insulin resistance even decades later, according to the study.  

Reference:
Breastfeeding's legacy may protect against diabetes. Study of 18 women shows effects of insulin levels and sensitivity (Press release) Dallas, TX, August 25, 2020, ScienceDaily, accessed August 26, 2020