Novel Risk Factors Add to Diabetes in African Americans

Two nontraditional risk factors-diminished lung function and low serum potassium levels-are important contributors to the racial disparity in diabetes mellitus (DM) risk among African Americans, according to a new study that found these risk factors have nearly the same impact as obesity.

“We have always assumed that the traditional risk factors would account for a majority of the racial disparity in diabetes risk, specifically differences in rates of obesity and measures of socioeconomic status. Although we did think that these novel risk factors would account for some of this disparity, we were surprised to find that each of these novel risk factors was as important a contributor to this disparity as obesity,”  Ranee Chatterjee, MD, MPH, Assistant Professor of General Internal Medicine at Duke University, Durham, North Carolina, told ConsultantLive.

Dr Chatterjee and colleagues analyzed data from nearly 11,200 patients with type 2 DM, including 8840 whites and 2322 African Americans. As expected, traditional risk factors had the greatest explanatory effects for the difference in DM risk between the races. More of the African Americans were heavier, had higher blood pressure, and were more likely to have lower incomes, Dr Chatterjee noted. These risk factors accounted for about 42% of the increased tendency for type 2 DM to occur among the African Americans.

Other, less well-known factors also surfaced, notably low lung function (as measured by forced vital capacity) and lower serum potassium levels among the African Americans in whom DM developed. Obesity accounted for a 22% increased risk of DM. Low lung function had nearly the same impact, accounting for a 21.7% increased risk among the African American patients with DM. Low serum potassium levels accounted for 17.7% of the increased risk.

“Other environmental, cultural, metabolic, and genetic factors are likely to contribute to the increased risk of type 2 diabetes among African Americans. These novel risk factors for diabetes may help us pinpoint who is at risk for developing diabetes,” said Dr Chatterjee. “Based on these novel risk factors, in the future, there may be additional recommendations other than weight loss and healthy lifestyle that will help to reduce a patient’s risk of developing diabetes.”

It is unclear what role reduced lung function and low potassium levels might play in type 2 DM, whether they are markers, causes, or consequences of the disease. “This is precisely what needs to be studied further to pinpoint the mechanism of association,” Dr Chatterjee said, adding that research may provide potential new avenues for developing treatments.

As of now, Dr Chatterjee suggests that “the information on the known risk factors is still the most important to help determine the risk of diabetes-a patient’s weight, family history of diabetes, presence of hypertension, and lifestyle. However, if these novel risk factors are confirmed in other studies, then these risk factors could potentially be included in diabetes risk scores, particularly for African Americans.”

The researchers published their results in the February 2014 issue of the Journal of General Internal Medicine.