Parathyroid Gland Response to Vitamin D Deficiency in Type 2 Diabetes Mellitus: An Observational Study

Background Studies have linked vitamin D deficiency with the risk of type 2 diabetes mellitus (T2DM) and to the development of chronic complication of diabetes. Vitamin D receptors (VDR) have been found in many tissues in the body including the pancreas, a finding that indicates its role in insulin secretion. In addition, many studies have demonstrated the role of vitamin D and its receptor in insulin sensitivity and signal transduction. Vitamin D deficiency is common throughout the world, but not all vitamin D deficiencies are accompanied by a rise in parathyroid hormone (PTH). The present study was conducted to assess vitamin D deficiency in type 2 diabetic patients in comparison to healthy control and to determine parathyroid gland response to vitamin D deficiency in both groups. Methods This observational study was performed during a period from January to October 2018. The study included 151 type 2 diabetic patients selected from three diabetes clinics and 43 age and sex-matched healthy subjects. Informed consent and clinical information were obtained from all participants before the study. Results of the laboratory analysis for serum 25-hydroxyvitamin D (25-OHD), PTH, calcium, and phosphorous were recorded. The data was analyzed using the statistical package for the social sciences (SPSS) Statistics 17. Results The results showed low vitamin D concentration in both groups; however, there was no significant difference in vitamin D concentration between diabetic patients and the control patients. A high percentage of PTH level was found in severe vitamin D deficient diabetic patients and healthy controls. The higher percentage of diabetic and normal subjects with mild vitamin D deficiency had a normal PTH level. All healthy subjects with vitamin D insufficiency showed normal PTH concentration. About 10% of diabetic patients with severe vitamin D deficiency had a low PTH level. Conclusion The population in our study was generally deficient in 25-OHD irrespective of diabetes mellitus, indicating a greater need for vitamin D supplementation. Not all vitamin D deficient patients have high PTH levels, a finding that supports the emergence of new criteria for vitamin D deficiency, diagnosis and treatment, and highlights the importance of testing PTH in this regard.