Insulin levels in African American children worsen as they progress through puberty

Insulin levels in African American children worsen as they progress through puberty while those same levels don't change in their Caucasian counterparts, says new University of Alberta research that shows puberty is a key developmental period affecting diabetes risk.

Dr. Geoff Ball, from the Faculty of Medicine and Dentistry at the U of A, was part of a team of researchers who conducted a unique longitudinal study that looked into the underlying physical and ethnicity-specific characteristics of insulin resistance in childhood and adolescence. They evaluated the dynamics of insulin sensitivity, insulin secretion and pancreatic beta-cell function in African American and Caucasian children through the stages of puberty. The research, which included investigators from the University of Southern California, Tufts University and the University of Alabama at Birmingham, was recently published in "The Journal of Pediatrics".

The study took place in Alabama over seven years, where participants were part of an ongoing study of body composition, energy expenditure and risk factors for Type 2 diabetes and cardiovascular disease. "This was a unique opportunity to be able to examine puberty-related health changes in these boys and girls," said Ball. "It has been difficult for researchers to previously study whether the effects of puberty differ across ethnic groups, so we were fortunate. We're studying the early genesis of what might lead to Type 2 diabetes and it will give us a clearer understanding of physiological changes that can help explain health risks."

The study confirmed that African American kids are more insulin resistant than Caucasian kids. None of the boys and girls were diagnosed with Type 2 diabetes, but insulin levels were markedly different between the two ethnic groups. The measure of pancreatic beta-cell function decreased in African American youth throughout puberty while the level remained static in Caucasian kids. These data demonstrated that puberty may have a unique effect on beta cell compensation to insulin resistance in young African Americans.

Puberty is a transient phase that may act as an accelerator to increase diabetes risk in some individuals, said Ball, also director of the Pediatric Centre for Weight and Health (PCWH) at the Stollery Children's Hospital in Edmonton. Insulin sensitivity usually decreases at puberty onset, but most often returns to normal afterwards. Our data reveal that a return to normal or baseline levels may not occur in all children, including African Americans, who we know are at increased risk of Type 2 diabetes," he said. "Puberty is just one part of this picture; we need to consider a host of factors that contribute to diabetes risk , but we now know that physiological changes during puberty may make an important contribution to the risk profile."