Effect of Vitamin D Supplementation in Type 2 Diabetes Patients with Tuberculosis: A Systematic Review

Background: Diabetes mellitus (DM) and tuberculosis (TB) have been recognized as re-emerging epidemics, especially in developing countries. Among all the risk factors, diabetes causes immunosuppression, increasing the risk of active TB three times. Vitamin D has been found as a link between DM-TB co-morbidity. Objective: Vitamin D affects the immune response, suppresses Mycobacterium tuberculosis (Mtb) growth, and affects insulin secretion. The present systematic review determines the effect of vitamin D supplementation on clinical and therapeutic outcomes of DM-TB patients. Method: A comprehensive literature search was carried out in PubMed, Cochrane, Web of Science, and Scopus database to determine eligible studies from inception to January 2021. Out of the 639 articles retrieved, three randomized controlled trials (RCTs) were included in the systematic review. Result: The effect of vitamin D-3 or oral cholecalciferol supplementation was assessed on outcomes, such as duration to sputum smear conversion, TB scores improvement, change in glycemic parameters, including HbAlc, FBS, and PLBS, and laboratory parameters, such as Hb, ESR, and CRP. Duration of sputum smear conversion was decreased by two weeks in the vitamin D, supplemented group in two studies. TB score improvement and changes in glycemic parameters were inclined towards supplemented group; however, they were not significant. Conclusion: The overall effect of vitamin D-3 supplementation on TB patients with DM was not significant. Further studies are required in the future examining the effect of supplementation on outcomes in this population.