Comparison of vitamin D levels in Diabetic nephropathy and Non-diabetic chronic kidney disease

Background and Aims: Diabetic Nephropathy is the most common renal complication of diabetes mellitus and a leading cause of end-stage renal disease. A deficiency in 25(OH) D has been linked to cardiovascular disease, diabetes and the progression of chronic kidney disease (CKD). Our aim was to determine vitamin D levels in different stages of diabetic nephropathy and non diabetic CKD and to compare it with the control subjects. Methods: This study was conducted in summer 2013 on 75 subjects divided into 3 groups: group (1): 15 healthy controls, group (2): 15 non diabetics with CKD and group (3): 45 type 2 diabetics who were subdivided into 3 groups according to albumin-to-creatinine ratio (ACR); (3a): 15 patients with normoalbuminuria; (3b): 15 patients with microalbuminuria and (3c): 15 patients with macroalbuminuria. Laboratory tests included FBS, HbA1c, CBC, urea, serum creatinine, ACR, eGFR and 25-hydroxyvitamin D. Results: There was a significant decrease in vitamin D levels in groups 2, 3a, 3b and 3c compared to control group (31.13±7.60, 64.20±10.70, 49.19±12.02, 20.40±9.48 vs. 79.20±19.06 nmol/L respectively, p<0.001). Also, there was significant difference between patient groups. Vitamin D levels were negatively correlated with age, duration of diabetes, FBS, HbA1c, creatinine, urea and ACR and positively correlated with hemoglobin and creatinine clearance in diabetics and all studied groups (p<0.001). Blood urea was the most important predictor of vitamin D levels followed by HbA1c and creatinine. Conclusion: Vitamin D levels were decreased in diabetics and in CKD. The higher the proteinuria the lower was the vitamin D levels.