Nontraditional Risk Factors Illuminate Racial Disparities in Diabetes

Two surprising risk factors—diminished lung function and low serum potassium levels—appear to have nearly the same impact as obesity in explaining why blacks are disproportionately prone to developing type 2 diabetes, researchers at Duke Medicine report.

The finding, published in theJournal of General Internal Medicine, clarifies some of the large racial disparities associated with diabetes risk and provides potential new avenues for developing treatments.

According to estimates from the National Health and Nutrition Exam Survey, the prevalence of diabetes is 70% higher among blacks than non-Hispanic whites. Traditional risk factors such as obesity, socioeconomic status, diet, and behavioral factors account for some of the racial disparities, but not all.

“Other environmental, cultural, metabolic, and genetic factors are likely to contribute to the increased risk of type 2 diabetes among African Americans,” says lead author Ranee Chatterjee, MD, MPH, an assistant professor of general internal medicine at Duke.

“More recently, nontraditional risk factors have been identified, including dietary factors, markers of chronic inflammation, metabolic abnormalities, genetic markers and others,” Chatterjee says. “The impact of these nontraditional risk factors on people of different races has not been studied, so we set out to see what proportion of the risk they might account for in African Americans and whites.”

Chatterjee and colleagues analyzed data from nearly 11,200 people with type 2 diabetes, including 8,840 whites and 2,322 blacks. Among the blacks, many well-known distinctions emerged: there were more women; they were heavier; they had higher blood pressure; and they were more likely to have lower incomes.

Those and other known risk factors accounted for about 42% of the increased tendency for type 2 diabetes among blacks.

Other, less well-known factors also surfaced, notably low lung function and lower serum potassium levels among the blacks who developed diabetes. Compared with obesity, which accounts for a 22% increased risk of developing diabetes, low lung function (measured as forced vital capacity) was nearly equally culpable, accounting for a 21.7% increased risk among the black diabetes patients. Low serum potassium levels accounted for 17.7% of the increased risk.

Chatterjee says it is unclear what role reduced lung function and low potassium levels might play in type 2 diabetes; whether they are markers, causes or consequences of the disease needs additional study. She says both factors are typically different among blacks and whites.

“We were surprised at the findings,” Chatterjee says. “It’s not clear how these nontraditional risk factors mediate the racial disparities in diabetes risk, but they suggest there are additional biological or environmental causes driving this disparity. Identifying the mediators of the racial disparities in type 2 diabetes risk may indicate where we need to focus research and development of interventions.”

Source: Duke Medicine