Association of A1C levels with vitamin D status in U.S. adults: data from the National Health and Nutrition Examination Survey.

Objective: Data relating vitamin D status with indices of glucose homeostasis as manifested by A1C in the U.S. adult population are few.

Research Design And Methods: We examined the association between serum 25 hydroxyvitamin D [25(OH)D] and A1C levels in 9,773 adults (age >or=18 years old) participating in the 2003-2006 National Health and Nutrition Examination Survey. Multivariate linear regression analyzed the association after accounting for potential confounders. RESULTS Serum 25(OH)D levels were inversely associated with A1C levels in subjects age 35-74 years (P = 0.0045) and those who did not report a history of diabetes (P = 0.0282).

Conclusions: These findings support a mechanistic link between serum vitamin D concentrations, glucose homeostasis, and the evolution of diabetes in a large segment of the U.S. adult population. Screening people with elevated A1C levels for vitamin D insufficiency should be considered.