The effects of calcitriol on albuminuria in patients with type-2 diabetes mellitus.

The renin-angiotensin system has a major role in the development of diabetic nephropathy (DN). It is reported that vitamin D analogues are able to suppress renin excretion. Thus, this study was conducted to determine whether there is any correlation between albuminuria as a marker of DN with vitamin D levels in diabetic patients. Also, an assessment was made on the effects of vitamin D therapy on albuminuria in this group of patients. We conducted this cross-sectional study on 119 outpatients with type-2 diabetes. The serum levels of 25-hydroxy vitamin D [25 (OH) D] and the albumin to creatinine ratio were assessed in all the study patients. Patients with vitamin D deficiency/insufficiency received calcitriol therapy for eight weeks, following which the laboratory tests were repeated. The mean age of the study patients was 55.3 ± 11.2 years, 43 (36.13%) had vitamin D insufficiency [25 (OH) D <25 ng/mL] and 31 (26.1%) had vitamin D deficiency [25 (OH) D <15 ng/mL]. We found a significant correlation between 25 (OH) D levels and presence of microalbuminuria (P = 0.04) in patients with vitamin D deficiency. Therapy with calcitriol had a beneficial effect on the albumin excretion rate, although this change was not significant (P = 0.22). However, the effects of calcitriol on reduction of diastolic blood pressure (P = 0.004), glycosylated hemoglobin (P = 0.014) and levels of total cholesterol (P = 0.019), low-density lipoprotein (0.04) and high-density lipoprotein (P = 0.001) was significant. Our study suggests that vitamin D deficiency has a negative effect on albuminuria in diabetic patients, and its replacement may be associated with a beneficial effect on the risk factors of DN, such as hyperlipidemia and hypertension.