Africans and Diabetes.

"We found gene expression profiles that suggest that carbohydrate metabolism should be different in the African-Americans in our population compared to Caucasians, Dr. Cam Patterson, chief of cardiology and director of the McAllister Heart Institute at the University of North Carolina, said in a university news release.
{snip}
Black people may have developed a different way of metabolizing glucose -- sugars"
{snip}
That, in turn, could lead to higher rates of diabetes in blacks."

This is in line with Henry Harpending's work reported in his book 'The 10,000 Year Explosion: How Civilization Accelerated Human Evolution'