Serum 25-hydroxyvitamin D3 concentrations and carotid artery intima-media thickness among type 2 diabetic patients

Objective To estimate the prevalence of hypovitaminosis D among type 2 diabetic adults and to assess the relationship between hypovitaminosis D and intimal medial thickening (IMT) of the common carotid artery, a marker of preclinical atherosclerosis. Design, patients and measurements We compared winter serum 25-hydroxyvitamin D3 [25(OH)D] concentrations in 390 consecutive type 2 diabetic patients and 390 nondiabetic controls who were comparable for age and sex. Common carotid IMT was measured with ultrasonography only in diabetic patients by a single trained operator blinded to subjects' details. Results The prevalence of hypovitaminosis D (i.e. 25(OH)D <= 37.5 nmol/l) was higher in diabetic patients (34.0 vs 16.4%, P < 0.001) than in controls. Among diabetic patients, those with hypovitaminosis D (n = 130) had a marked increase in common carotid IMT (1.10 +/- 0.15 vs 0.87 +/- 0.14 mm, P < 0.001) when compared with their vitamin D-sufficient counterparts (n = 260). These patients also had significantly higher haemoglobin A1c, fibrinogen and C-reactive protein (hs-CRP) concentrations. In multivariate regression analysis, low 25(OH)D concentrations independently predicted carotid IMT (P < 0.001) in people with type 2 diabetes after adjustment for classical risk factors, diabetes duration, HbA1c, calcium, renal function tests, inflammatory markers, use of medications, and presence of the metabolic syndrome (as defined by the Adult Treatment Panel III criteria). Conclusions Hypovitaminosis D is highly prevalent in type 2 diabetic adults and is strongly and independently associated with increased carotid IMT. Further investigation into whether vitamin D may play a role in the prevention of atherosclerosis appears to be warranted.