In this study, we combined data from the ARIC and JHS cohorts to determine: 1) if there is an association between KCNJ11 variants (rs5215 and rs5219) and risk of incident type 2 diabetes; 2) if these genetic variants are significant effect modifiers of the association between serum K and incident diabetes risk; and 3) if these associations and interactions differ by race. The gene discussed is KCNJ11; the disease is diabetes mellitus.