Association between Serum 25- Hydroxyvitamin D and Urinary Albumin in Type 2 Diabetes Mellitus

Abstract Background: Diabetic kidney disease (DKD) is the most common long-term microvascular complication and the leading cause of chronic kidney disease and end-stage renal disease. The main clinical manifestations of DKD are progressive albuminuria and decline in renal function. Vitamin D is transported through the human body in the bloodstream by binding to vitamin D binding protein (VDBP). The complex formation of VDBP/25-dihydroxyvitamin D, its filtration, and the reabsorption of this complex in the proximal renal tubular cells are critical for the retrieval and activation of vitamin D. People with renal damage, like diabetic patients with DKD, have increased urinary VDBP concentrations. This urinary loss of VDBP might have an effect on vitamin D levels. Inthis study, we determined the association between 25-hydroxyvitamin D (25OHD) level and urinary albumin in patients with type 2 diabetes mellitus. Materials and Methods: This cross sectional analytical study included 108 patients with type 2 diabetes mellitus (type 2 DM). They were classified into two groups based on the level of urinary albumin-to-creatinine ratio (UACR). UACR < 30 mg/g was defined as normoalbuminuria, while UACR levels between 30–300 mg/g was defined as microalbuminuria. Serum 25OHD levels among two UACR groups were compared. The relationship between albuminuria and 25OHD was analysed. Results: Vitamin D deficiency is more in type 2 DM with microalbuminuria than normoalbuminuria. The percentage of patients with vitamin D deficiency (<30 ng/mL) in the microalbuminuria group was significantly greater than that in the normoalbuminuria group (87 % vs. 40.7 %, P < 0.05). We also got significantly negative correlation between serum 25(OH)D concentrations and urinary albumin: creatinine ratio (UACR) (r = −0.315) p < 0.001. Conclusion: This study states that an association exists between Vitamin D deficiency and microalbuminuria in type 2 diabetes. The prevalence of vitamin D deficiency in type 2 diabetes patients with albuminuria was overtly higher than that in patients without albuminuria. Thus, from the study we can conclude that patients with DKD are more likely to be vitamin D deficient than those without DKD.