Determinants of coronary artery calcification in diabetics with and without nephropathy

Background. In the general population, including those with diabetes mellitus, coronary artery calcification (CAC) correlates with atherosclerotic plaque burden. On the other hand, accumulating evidence suggests that disordered mineral metabolism significantly contributes to the vascular calcification in individuals with end-stage renal disease (ESRD). Methods. In order to determine the relative contribution of accelerated atherosclerosis and disordered mineral metabolism to CAC in chronic kidney disease, a pilot study of 90 patients with type 2 diabetes mellitus was done [age, 40-65 years; normoalbuminuria, N=30; diabetic nephropathy (DN), N=60]. Results. CAC was more prevalent and severe among individuals with DN compared to diabetic controls (odds ratio for prevalence 8.1, 95% CI 2.3-28.5; median scores, 66 vs. 4, P<0.001). None of the 4 measures of disordered mineral metabolism evaluated in this study (serum calcium, phosphorus, parathyroid hormone, and 1,25 di-hydroxy vitamin D levels) correlated with the prevalence or severity of CAC, or accounted for the differences seen between DN and diabetic controls. On the other hand, the difference in the severity of hypertension (number of antihypertensive medications) appeared to account for the differences in CAC burden seen between DN and diabetic controls. Conclusion. This first such study of nondialyzed individuals with DN suggests that, unlike ESRD patients, the high CAC burden seen at earlier stages of diabetic chronic kidney disease is probably unrelated to disordered mineral metabolism. The relationship between the severity of hypertension and CAC burden provides a probable target for intervention in the predialysis phase of DN.