Objective: To examine the relationship between serum levels of 25-hydroxyvitamin D (25[OH]D), polymorphisms in vitamin D associated genes, and the presence and progression of coronary artery calcification (CAC) in adults with type 1 diabetes.

Research Design and Methods: This prospective study included 374 non-Hispanic white (NHW) subjects with type 1 diabetes (mean age 40 ± 9 years; 46% male). CAC was measured at the baseline, three and six-year follow-up visits by electron beam CT. Serum 25[OH]D levels were measured by liquid chromatography tandem mass spectrometry at the 3-year visit.

Results: Normal (> 30 ng/ml), insufficient (20-30 ng/ml), and deficient (< 20 ng/ml) 25-OHD levels were present in, respectively, 65%, 25%, and 10% of the individuals with type 1 diabetes. 25[OH]D deficiency was associated with the presence of CAC at the 3-year visit, odds ratio (OR) = 3.3 (95% CI 1.6-7.0), adjusting for age, sex, and hours of daylight. In subjects free of CAC at the 3-year visit, 25[OH]D deficiency predicted development of CAC over the next 3 years in those with the vitamin D receptor M1T CC genotype (OR=6.5 [1.1-40.2], p=0.04), than those with the CT or TT genotype (OR=1.6 [0.3-8.6], p=0.57).

Conclusions: Vitamin D deficiency independently predicts prevalence and development of coronary calcification, a marker of coronary artery plaque burden, in individuals with type 1 diabetes.