Breastfeeding for six months or more nearly halves the risk of women developing type 2 diabetes, a new long-term US study has found.
The findings, published in JAMA Internal Medicine, are based on data for more than 1,200 young women aged 18 to 30 who enrolled in a 30-year heart disease study in the mid 1980s.
“The incidence of diabetes decreased in a graded manner as breastfeeding duration increased”
None of the women, who all went to have one or more children, had diabetes at the start of the study or before becoming pregnant. All reported how long they breastfed their babies and were screened for diabetes up to seven times during the 30 years up to 2016.
The researchers found those who breastfed every child for six months or more saw a 47% reduction in their risk of developing type 2 diabetes, compared with those who did not breastfeed at all. Meanwhile, the study found that women who breastfed for six months or less saw a 25% reduction in diabetes risk.
The team from the research division of US healthcare provider Kaiser Permanente found the link between the length of time women breastfed children and lower risk of diabetes was “very strong” even when a range of other risk factors such as obesity and lifestyle were taken into account.
There may well be a biological reason for the association, suggested the researchers.
“The incidence of diabetes decreased in a graded manner as breastfeeding duration increased, regardless of race, gestational diabetes, lifestyle behaviours, body size, and other metabolic risk factors measured before pregnancy, implying the possibility that the underlying mechanism may be biological,” said lead author and senior research scientist Erica Gunderson.
For example, the study authors suggested one such mechanism could be the influence of hormones linked to lactation on the pancreatic cells that control blood insulin and therefore blood sugar levels.
“This is yet another reason that nurses should support women and their families to breastfeed as long as possible”
Dr Tracy Flanagan, director of women’s health for Kaiser Permanente Northern California, said the research added to evidence of the benefits of breastfeeding.
“We have known for a long time that breastfeeding has many benefits both for mothers and babies, however, previous evidence showed only weak effects on chronic disease in women,” she said.
“Now we see much stronger protection from this new study showing that mothers who breastfeed for months after their delivery, may be reducing their risk of developing type 2 diabetes by up to one half as they get older,” she said.
“This is yet another reason that doctors, nurses, and hospitals as well as policymakers should support women and their families to breastfeed as long as possible,” she added.