As blood levels of vitamin D increase, the risk of diabetes decreases in non-Hispanic whites and Mexican Americans - but not in blacks - researchers have found.

The findings 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,” Dr. Robert Scragg, from the University of Auckland in New Zealand, and colleagues suggest in the medical journal Diabetes Care.

The results are based on a study of 6228 subjects, representative of the US population, who participated in the Third National Health and Nutrition Examination Survey.

Whites with the highest vitamin D levels had only one quarter the risk of having diabetes compared to those with the lowest levels. For Mexican Americans, the comparative risk dropped even further.

The reason why this pattern was not seen in blacks is unclear, but the researchers believe it may “reflect decreased sensitivity to vitamin D and/or related hormones” in this group.

The team calls for further research to confirm the findings and to pinpoint underlying mechanisms, but notes that simple and cheap ways to increase vitamin D levels are readily available.

SOURCE: Diabetes Care, December 2004.