Background: The progression of diabetic kidney disease (DKD) is highly correlated with proteinuria. Previous studies have suggested that vitamin D treatment may reduce proteinuria and has the potential to delay the progression of renal disease.
Objective: To evaluate efficacy of oral calcitriol to decrease proteinuria in type 2 diabetic mellitus (T2DM) patients with DKD.
Material and Method: In this 16-week, open label, prospective, randomized controlled study, 91 patients with T2DM with estimated glomerular filtration rate (eGFR) greater than 15 ml/min/1.73 m2 and urine protein to creatinine ratio (UPCR) greater than 1 g/g were enrolled. They were randomly assigned to receive either oral calcitriol 0.5 mcg twice weekly (n = 46) or without oral calcitriol (n = 45). The primary outcome was determined by the change of UPCR from baseline after 16 weeks of treatment of both groups.
Results: At randomization, the mean UPCR was 3.7 + 2.2 g/g in the calcitriol group and 3.4 + 2.1 g/g in the control group. The mean UPCR at 16-week follow-up was 2.9 + 1.7 g/g in the calcitriol group and 3.5 + 2.3 g/g in the control group. Percent changes in UPCR from baseline to the last evaluation in the calcitriol and control groups were -18.7% and + 9.9% (p < 0.01) respectively. Patients with 30% or more decrement in proteinuria occurred 43.5% of the time in the calcitriol group and 11.1% in the control group (p < 0.01). The eGFR and blood pressure did not differ significantly between the two groups. No serious adverse side effects were noted in either group.
Conclusion: Calcitriol treatment can reduce proteinuria in patients with DKD without serious adverse events.

Keywords: Diabetic kidney disease, Proteinuria, Calcitriol