The relationship between microvascular complications and vitamin D deficiency in type 2 diabetes mellitus

BACKGROUND Vitamin D deficiency is reported as a possible risk factor for the development of diabetes in several epidemiologic studies. In this study, we investigated the frequency of 25-OH vitamin D deficiency in type 2 diabetes mellitus and the relationship between 25-OH vitamin D deficiency and the prevalence of microvascular complications. METHODS In this retrospective study, we evaluated the medical records of 557 patients with type 2 diabetes admitted to the Endocrinology Outpatient Clinic from January to March 2010 and 112 healthy controls randomly selected from individuals admitted to the hospital for a check-up and who had a laboratory result for serum 25-OH vitamin D concentrations at screening. The levels of 25-OH vitamin D in patients with type 2 diabetes and the relationship between 25-OH vitamin D deficiency and microvascular complications were investigated. RESULTS No significant difference in serum 25-OH vitamin D concentrations was observed between the diabetic and control groups. No correlation was observed between HbA1C and serum 25-OH vitamin D levels. Serum 25-OH vitamin D levels were lower in diabetic patients with nephropathy, and patients not using any medication, i.e., those treated with dietary changes alone, had a higher prevalence of nephropathy. CONCLUSION Vitamin D deficiency is more common in diabetic patients with nephropathy. When microvascular complications were evaluated, vitamin D levels were found to be lower in patients in whom these complications were more severe. Vitamin D deficiency is therefore associated with microvascular complications in diabetic patients.