Diabetes Mellitus type 1 (DM1) results from destruction of the pancreatic beta cells by an immunological process, which may progress to kidney complications. Both genetic and environmental factors are involved in the pathogenesis of type 1 diabetes, and vitamin D deficiency appears as a candidate among the risk factors for developing both diabetes and diabetic nephropathy. The objective of this study was to evaluate the existence of an association between low levels of vitamin D with the presence and degree of diabetic nephropathy in patients with type 1 diabetes. Additionally, our study aimed to establish the prevalence of vitamin D deficiency in normal individuals of our region and determine if it differs from DM1 patients. A cross-sectional study, between November 2013 and December 2014, in which levels of 25 (OH) D and albuminuria were analyzed in 37 patients with DM1, normal creatinine levels and 36 control subjects. The patients with DM1 and hypovitaminosis D had higher levels of albuminuria compared with those with normal vitamin D levels (albuminuria = log10 1.92 vs. 1.44; p <0.05). When the group of patients was separeted according to the stage of diabetic nephropathy in those with normoalbuminuria, microalbuminuria, and macroalbuminuria, we found lower levels of 25(OH)D in the latter when compared to the first two groups (26.7 ± 6.2, 24.8 and 15.9 ± 7 ± 7.6 ng / mL; p <0.05, respectively). In DM1 group, we found correlations between vitamin D levels with the levels of albuminuria and diabetic nephropathy stages (r= -0.5, p<0.01 r= -0.4; p <0.05, respectively). Additionally, the prevalence of vitamin D deficiency among control subjects was quite high (78%), and there was no difference compared to patients with DM1, whose prevalence was 73%. Patients with type 1 diabetes when compared to control group also showed no difference regarding the average levels of 25(OH)D (24.2 ± 7.4 versus 25.8 ± 11.2 ng / mL, NS). Our data suggest an association between reduced levels of vitamin D and the presence and severity of diabetic nephropathy. In addition, patients with type 1 diabetes mellitus, when compared to normal control subjects in our region did not differ in average and status of 25(OH)D levels.
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