Effect of Vitamin D Supplementation on Pancreatic Β -Cell Function in Patients with Type 1 Diabetes Mellitus and Vitamin D Deficiency: A Clinical Trial Study

Background Considering the increasing prevalence of type 1 diabetes mellitus (T1DM) as an autoimmune disease in recent years and the positive effects of vitamin D (VD) on this disease, especially the preventive effect of VD on progressive reduction of pancreatic β-cells, we aimed to investigate the effect of VD on pancreatic β-cell function in T1DM patients. Materials and Methods From Sep 2016 to Nov 2017, this single-blind clinical trial study was performed on patients who have affected with T1DM in the last five years, referred to Endocrinology Clinic of Amirkola Children's Hospital in Babol city of Iran. The patients with VD level less than 30 ng/mL were treated with 50, 000 IU Pearl VD for 9 months. The patients' C-peptide, 25 (OH) D, HbA1C and total daily dose (TDD) insulin were compared at the beginning and end of the study. Data were analyzed using SPSS software version 22.0. Results By examining all 30 randomly selected children meeting the inclusion criteria, it was found that VD increased the C-peptide level (0.06 nmol/L), slightly improved the pancreatic β-cell function as well as decreased their HbA1c (0.64%), and TDD insulin levels (0.05 unit) although none of the relationships was significant. However, a significant decrease in HbA1c level was found in the female group (p=0.04) as well as in the age group less than 10 years (p=0.007). Conclusion VD intake had no significant effect on serum C-peptide levels and reduction of HbA1c and TDD insulin though a significant decrease in HbA1c level was observed in the female group and in the patients less than ten years.