Breast-feeding can protect against development of type 2 diabetes in youth of 3 ethnic groups, mediated in part by current weight status in childhood, according to the results of a study reported in the March issue of Diabetes Care.

"Among adults, breast-feeding in infancy has been associated with reduced risk of type 2 diabetes, but little is known regarding the potential beneficial effect of breast-feeding on the development of type 2 diabetes in adolescence," write Elizabeth J. Mayer-Davis, PhD, from the University of South Carolina in Columbia and colleagues from The SEARCH for Diabetes in Youth Case-Control Study.

"We hypothesized that youth with type 2 diabetes would be less likely to have been breast-fed compared with nondiabetic control youth and that this finding would be consistent across three race/ethnic groups of non-Hispanic whites, African Americans, and Hispanics and independent of maternal diabetes status. Further, we explored whether current BMI [body mass index] would account for any of the observed protective association."

WHAT DOES IT MEAN
Breast-feeding reduces the risk for incident type 2 diabetes primarily by reducing the risk for childhood obesity. Specifically, breast-feeding may set a lower satiety threshold; reduce insulin levels during infancy; and reduce exposure to chemicals and nitrates, which impair pancreatic beta-cell function.

"Breast-feeding appears to be protective against development of type 2 diabetes in youth, mediated in part by current weight status in childhood," the study authors write. "Attenuation of the odds ratios when BMI z-score was added to the models were consistent with a causal pathway in which breast-feeding may lower the risk for childhood overweight, which may in turn reduce risk for type 2 diabetes."

Breast-feeding has multiple salutary effects for children, and 1 of these effects appears to be a reduction in the risk for the development of type 2 diabetes. Breast-feeding reduces this risk primarily by reducing children's weight, but the precise means by which this occurs is unclear.

Breast-feeding may also set a lower and enduring satiety limit for infants, whereas overfeeding among bottle-fed infants can increase peak insulin levels and prolong the insulin response. Certain exposures associated with bottle-feeding, particularly to chemicals used to make plastic bottles and nitrates in tap water, can reduce pancreatic beta-cell function.

Some research has questioned whether children in different ethnic groups receive the same protection against type 2 diabetes associated with breast-feeding. The current study used the SEARCH study cohort to examine the effects of breast-feeding on rates of incident diabetes among African American, Hispanic, and non-Hispanic adolescents and young adults.

HOW DID THEY FIND IT
SEARCH was a multicenter study designed to detect factors associated with the risk for incident type 2 diabetes among persons at 20 years or younger in 2001. Cases were confirmed by the patients' healthcare providers.

Cases of patients with incident type 2 diabetes were compared with control subjects without diabetes from the same geographic areas. Researchers overrecruited Hispanics and African Americans into their study cohort.

The investigators queried the biological mothers for breast-feeding data, including the duration of breast-feeding and the timing of introduction of other foods.

Julie Gabriel, based on a study published in Diabetes Care. 2008;31:470-475.,/em>