A new study shows that diabetics who get an adequate amount of vitamin D are less likely to have their blood vessels clog. Those who do not get enough vitamin D, however, have immune cells bind to blood vessels near the heart, trapping cholesterol and blocking blood vessels.

“About 26 million Americans now have type 2 diabetes,” said Dr. Carlos Bernal-Mizrachi, co-author of the study and assistant professor of cell biology and physiology at the Washington University School of Medicine. “And as obesity rates rise, we expect even more people will develop diabetes. Those patients are more likely to experience heart problems due to an increase in vascular inflammation, so we have been investigating why this occurs.”

Bernal-Mizrachi had previously found that vitamin D plays a “key” role in heart disease. The new research shows that a certain type of white blood cell is mire likely to adhere to cells in the wall of blood vessels when vitamin D levels are low.

The study, published in the Journal of Biological Chemistry, looked at vitamin D levels in 43 patients with type 2 diabetes and 25 others who did not have diabetes. It found that white blood cells called monocytes were more likely to transform in to macrophages and adhere to the walls of blood vessels in patients with low vitamin D. This causes cholesterol to build and blocks blood flow.

“We took everything into account,” said Dr. Amy Riek, lead author of the study. “We looked at blood pressure, cholesterol, diabetes control, body weight and race. But only vitamin D levels correlated to whether these cells stuck to the blood vessel wall.”

Riek and Bernal-Mizrachi are now treating mice with vitamin D to see whether giving the vitamin to diabetics might reverse their risk of clogged arteries. They are also conducting clinical trials in patients.

“In the future, we hope to generate medications, potentially even vitamin D itself, that help prevent the deposit of cholesterol in the blood vessels,” said Bernal-Mizrachi. “Previous studies have linked vitamin D deficiency in these patients to increases in cardiovascular disease and in mortality. Other work has suggested that vitamin D may improve insulin release from the pancreas and insulin sensitivity. Our ultimate goal is to intervene in people with diabetes and to see whether vitamin D might decrease inflammation, reduce blood pressure and lessen the likelihood that they will develop atherosclerosis or other vascular complications.”