Associations between Vitamin D and Type 2 Diabetes Mellitus: The Role of Vitamin D Receptor and Binding Protein

Background: Type 2 diabetes mellitus (T2DM) is a chronic disease that is characterized by β-cell dysfunction and resistance for insulin. Vitamin D is necessary for insulin secretion so it is a crucial factor in the development of T2DM. This study was done to investigate the association between serum 25-hydroxy Vitamin D [25(OH)3D], VDR (Vitamin D receptor) and VDBP (Vitamin D binding protein) with type 2 diabetic patients compared to control subjects. Subjects and Methods: This study carried out 110 female patients who were previously diagnosed with type 2 diabetes and 110 age, sex and weight matched as controls. All participants were subjected to full history taking, clinical examination and assessment of fasting blood glucose, HbA1c , lipid profile, 25-hydroxy Vitamin D [25(OH)3D], VDR and VDBP. Results: Results showed that the level of 25(OH)3D was significantly lower in diabetic group compared to controls and was significantly negatively correlated with glycated hemoglobin, serum total cholesterol and low density lipoprotein cholesterol in type 2 DM. Decreasing Vitamin D level was significantly associated with decreasing VDR. No significant association was found between Vit D and VDBP levels. Conclusions: Vitamin D deficiency is frequent in diabetic patients and associated with poor control and outcome. This suggests a role of Vitamin D in the pathogenesis and control of T2DM. Serum VDBP in diabetes may be independent to the level of 25(OH)3D and needs further studies.