NEW YORK (Reuters Health) – Baseline serum level of 25-hydroxyvitamin D is predictive of future glycemic status and insulin resistance, according to UK researchers.

In the October issue of Diabetes, Dr. Nita G. Forouhi of the Institute of Metabolic Science, Cambridge and colleagues note that there is accumulating evidence that lack of vitamin D may be associated with type 2 diabetes and associated risks.

To investigate further, the researchers randomly selected 524 nondiabetic subjects aged 40 to 69 years who were taking part in a population-based study.

After adjustment for factors such as age and sex, baseline serum 25(OH)D showed a significant inverse association with the 10-year risk of hyperglycemia, insulin resistance, homeostasis model assessment of insulin resistance (HOMA-IR) and metabolic syndrome z score.

The researchers did not find any significant association with lipids, blood pressure, or waist circumference, suggesting, they say, “that the association with metabolic syndrome risk is driven largely by the glucose and insulin component.”

After further adjustment for insulin growth factor 1, calcium and other variables, the association with 2-hour glucose, insulin and HOMA-IR remained significant.

Dr. Robert Scragg, the author of an accompanying editorial, told Reuters Health that “by showing that blood vitamin D levels predict blood glucose and insulin levels 10 years later, the study provides some of the strongest evidence to date that vitamin D may prevent diabetes.”

“If further studies confirm their findings,” concluded Dr. Scragg of the University of Auckland, New Zealand, “the next step will be for large clinical trials to determine with certainty whether vitamin D does reduce the risk of developing diabetes.”

Diabetes 2008;57:2619-2625.