A study, reported in Diabetes Care (December 2004), found that, as blood levels of vitamin D rise, the possibility of diabetes decreases in non-Hispanic Caucasians and Mexican Americansbut not in African Americans. The researchers based their findings on a study of 6228 participants, representative of the US population, who took part in the Third National Health and Nutrition Examination Survey.
The results of the study showed that Caucasians with the largest vitamin D levels had only one quarter the risk of having diabetes, compared with those with the lowest levels. In Mexican Americans, the comparative risk dropped even more. The researchers believe the reason why this pattern was not seen in African Americans is that it may "reflect decreased sensitivity to vitamin D and/or related hormones" in this group. Based on the data, the researchers said the finding may "offer an explanation, in part, for the generally lower prevalence of type 2 diabetes observed in Caucasian populations around the world compared with other ethnicities."