By David Liu

Thursday March 22, 2012 (foodconsumer.org) -- Early studies suggest vitamin D deficiency may increase risk for developing type 2 diabetes mellitus.  A new study published recently in Diabetologia has confirmed that people with prediabetes are more likely than those with normal glucose tolerance to develop type 2 diabetes.

The study led by A. Deleskog of Karolinska Institutet, Karolinska University Hospital in Stockholm, Sweden and colleagues found people who had prediabetes at baseline were 48 percent more likely to develop tyep 2 diabetes mellitus during a 8-to-10-year follow-up.

By definition used in the study, prediabetes refers to a condition in which a person has impaired fasting glucose, impaired glucose intolerance or the two combined.  American Diabetes Association says 78 million Americans live with pre-diabetes.

At the beginning of the study, the researchers tested blood samples from 980 women and 1398 men who had no diagnosed diabetes at baseline for a number of biomarkers including 25-hydroxyvitamin D [259OH)D], IGF or IGF-binding protein-1 at baseline.  Participants were also surveyed for their anthropometric and lifestyle data.

People who were found to have developed diabetes or prediabetes during the 8-to-10-year follow-up were considered as cases and compared to controls who were age and sex-matched and had normal glucose tolerance at both baseline and follow-up.

The researchers found that "Men but not women in the highest quartile of 25 (OH)D level had a decreased OR for developing type 2 diabetes after adjustment for confounders (OR 0.52, 95% CI 0.30, 0.90), an effect accounted for by individuals with prediabetes, but not with NGT (normal glucose intolerance, at baseline. In both sexes, progression from prediabetes to type 2 diabetes was reduced by about 25% per 10 nmol/l increase in 25(OH)D."

But a high IGFBP-1 value was a better predictor for a reduced risk of type 2 diabetes than high 25(OH)D in both men and women whereas high IGF-1 levels predicted a reduced risk only in men.

The authors of the study concluded that "High serum 25(OH)D concentrations predict a reduced risk of type 2 diabetes in individuals

with prediabetes, but not NGT. There were no significant interactions between 25(OH)D and IGFBP-1 or IGF-1 in terms of risk of diabetes. Our data suggest that vitamin D supplementation should be evaluated for the prevention of type 2 diabetes in prediabetic individuals."

An estimated 26 million Americans live with type 2 diabetes.  At higher risk for the disease are blacks, Latinos, Native Americans, and Asian Americans, Native Hawaiians and other Pacific Islanders, as well as elderly people, according to the American Diabetes Association.

Keywords: Keywords Impaired fasting, glucose Impaired glucose tolerance, Insulin-like growth factor, Type 2 diabetes, Vitamin D