Insufficient vitamin D levels linked to increased atherosclerosis in diabetics
Friday, November 16, 2012. The November 9, 2012 issue of The Journal of Biological Chemistry published an article by researchers at Washington University in St Louis that describes a protective effect for higher serum vitamin D levels against the development of atherosclerosis in patients with type 2 diabetes.
"About 26 million Americans now have type 2 diabetes," noted Carlos Bernal-Mizrachi, MD, the study's lead researcher. "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."
Dr Bernal-Mizrachi and his associates tested their hypothesis that monocytes (a type of white blood cell) from diabetics who are deficient in vitamin D would be likelier to promote atherosclerosis than those found in individuals who are vitamin D-sufficient. For the current study, serum 25-hydroxyvitamin D levels and other factors were measured in blood samples from 43 type 2 diabetics and 25 control subjects.
Diabetic patients who had sufficient serum levels of vitamin D of at least 30 nanograms per milliliter experienced less monocyte adhesion to endothelial cells (cells that line the blood vessels) in comparison with subjects with insufficient levels. Monocytes are transformed into cells called macrophages upon encountering inflammation. The adherence of macrophages to blood vessel walls, combined with accumulation of cholesterol, leads to the formation of plaque, which eventually impedes blood flow.
"We took everything into account," first author Amy E. Riek, MD noted. "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."
"In the future, we hope to generate medications, potentially even vitamin D itself, that help prevent the deposit of cholesterol in the blood vessels," added Dr Bernal-Mizrachi, who is an assistant professor of medicine and cell biology and physiology at Washington University School of Medicine. "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."