U.S. researchers say they found an inverse relationship between the level of vitamin D in the blood and the presence of risk factors for diabetes 2.

Dr. Joanna Mitri, a research fellow at Tufts Medical Center in Boston, said metabolic syndrome is a series of risk factors -- increased triglycerides, reduced levels of the "good," cholesterol, raised blood pressure and raised fasting blood sugar -- that increases the risk of heart disease and type 2 diabetes.

People with the highest blood levels of vitamin D had a 48 percent lower risk of having the metabolic syndrome than did those with the lowest vitamin D levels, the study found.

"This association has been documented before, but our study expands the association to people of diverse racial and ethnic backgrounds," Mitri said in a statement. "These include minority groups that are already at higher risk of diabetes."

In this study, all study participants were at risk of developing diabetes because they had prediabetes, abnormally high blood sugar levels that are not yet high enough to be classified as diabetes.

In the study, the group with the highest levels of vitamin D had a median concentration of 30.6 nanograms per milliliter and those in the lowest group had a median vitamin D concentration of 12.1 ng/mL. The risk of having the metabolic syndrome with a high vitamin D level was about one-half the risk with a low vitamin D level, Mitri said.

The findings were presented at The Endocrine Society's 94th annual meeting in Houston. (c) UPI