“Vitamin D deficiency is common worldwide and could be a novel risk factor for the development of coronary artery atherosclerosis,” says Ramachandra B. Naik, MD, of the Barbara Davis Centre 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 this patient population is associated with the initiation and acceleration of coronary artery calcification.
Furthermore, researchers have identified vitamin D-receptor gene (VDR) polymorphisms that may be responsible for lower 25-OHD levels. “There is a growing body of evidence to suggest that vitamin D deficiency with VDR polymorphism may accelerate atherosclerosis,” Dr. Naik says.
Dr. Naik assessed vitamin D levels, VDR polymorphisms, and coronary artery calcification in 375 patients with type 1 diabetes who participated in the Coronary Artery Calcification in Type 1 Diabetes study. Measurements were taken at the 3-year and 6-year study visits.
Patients had type 1 diabetes of at least 10 years’ duration. Vitamin D deficiency was defined as serum levels of 20 ng/mL or less, insufficiency was defined as levels of 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 D insufficiency.
“The TT phenotype of the Fok1 VDR is associated with significantly higher levels of vitamin D deficiency, and vitamin D status was independent of the diabetic state,” says Dr. Naik. Dr. Naik found that vitamin D deficiency was an independent predictor for coronary artery 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 coronary artery calcification between the 3- and 6-year assessments but only among patients initially 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 for atherosclerosis,” Dr. Naik says. He adds that glycemic control was not an influencing factor in this study.
