Vitamin D deficiency accelerates atherosclerosis in type 1 diabetics

"Vitamin D deficiency is common worldwide and could be a novel risk factor forthe development of coronary artery atherosclerosis," says Ramachandra B. Naik, MD,of the Barbara Davis Center for Childhood Diabetes, University of Colorado,Denver.

Dr. Naik presented study results indicating that although vitamin D (25-OHD)deficiency is not increased among type 1 diabetes patients, a deficiency in thispatient population is associated with the initiation and acceleration of coronaryartery calcification.

Furthermore, researchers have identified vitamin D-receptor gene (VDR)polymorphisms that may be responsible for lower 25-OHD levels. "There is a growingbody of evidence to suggest that vitamin D deficiency with VDR polymorphism mayaccelerate atherosclerosis," Dr. Naik says.

Dr. Naik assessed vitamin D levels, VDR polymorphisms, and coronary arterycalcification in 375 patients with type 1 diabetes who participated in the CoronaryArtery Calcification in Type 1 Diabetes study. Measurements were taken at the 3-yearand 6-year study visits.

Patients had type 1 diabetes of at least 10 years' duration. Vitamin D deficiencywas defined as serum levels of 20 ng/mL or less, insufficiency was defined as levelsof 21 to 30 ng/mL or less, and a normal vitamin D level was greater than 30 ng/mL.Of the 375 patients, about 10% were deficient and 20 to 30% had vitamin Dinsufficiency.

"The TT phenotype of the Fok1 VDR is associated with significantly higher levelsof vitamin D deficiency, and vitamin D status was independent of the diabeticstate," says Dr. Naik.Dr. Naik found that vitamin D deficiency was an independent predictor for coronaryartery calcification identified at the 3-year visit (odds ratio [OR]=2.8;p=0.003). Other predictors were age, type 1 diabetes status, and male sex(OR=2.3, 2.6, and 2.7, respectively; p=0.001).

Vitamin D deficiency was also a significant predictor of progression of coronaryartery calcification between the 3- and 6-year assessments but only among patientsinitially free of calcification at 3 years (p=0.05), Dr. Naik reports.

"In other words, both VDR phenotype and vitamin D deficiency are risk factors foratherosclerosis," Dr. Naik says. He adds that glycemic control was not aninfluencing factor in this study.