Association Between Vitamin D and Diabetic Kidney Disease

Background: Diabetic kidney disease (DKD) is the most important cause of end-stage renal failure. The aim of this study is to investigate whether there is an association between supplementation of vitamin D and DKD or not. Methods: The study was designed prospectively and initiated with a total of 81 patients with a history of type 2 diabetes mellitus (DM) and diagnosed with stage 3 or 4 diabetic nephropathy (DN), who applied to Ankara University Faculty of Medicine between July 2011 and February 2013. It was completed with a total of 63 patients, 38 female (60.3%) and 25 male (39.7%), during the six-month follow-up period. The inclusion criteria were as follows: microalbumin ≥ 30 mg/day in 24 h urine, for which at least two measurements were obtained; age ≥ 18; HbA1c ≤ 8%; eGFR (estimated glomerular filtration rate) ≥ 30 mL/min; and, in addition, type 2 DM diagnosis. Patients with microalbumin levels of 30-299 mg/24 h were included in the microalbuminuria group, whereas patients with ≥300 mg were included in the macroalbuminuria group. An oral dose of 300,000 IU vitamin D3 replacement was given to patients with vitamin D deficiency and insufficiency. Results: In both groups, a significant increase in vitamin D levels at six months compared to baseline was observed, while a significant decrease in 24 h urine microalbumin and protein levels was observed at six months. Considering these results, vitamin D was considered to have a positive effect on 24 h urine microalbumin and protein levels. Conclusions: In both groups, a significant increase in vitamin D levels and a significant decrease in microalbumin and protein levels were detected at the sixth month via 24 h urine tests. Therefore, vitamin D replacement is thought to be beneficial for DKD treatment because of its antiproteinuric effect.