Vitamin D Deficiency in Tuberculosis and Diabetes Mellitus - A Cluster Analysis

Background: Diabetes mellitus and tuberculosis are a dual disease burden, and diabetes is associated with a threefold risk of developing tuberculosis. Though India is considered to have an abundance of sunlight, the prevalence of deficiency of vitamin D is high, which is shown to cause impairment in the macrophage-initiated immune response against Mycobacterium tuberculosis. Methods: Our study estimated the prevalence of mean levels and determinants of vitamin D deficiency in patients with tuberculosis or diabetes and those with both tuberculosis and diabetes. A cluster analysis was performed to identify whether these patients belong to distinct clusters and evaluate whether vitamin D levels were significantly different between clusters. Results: The study observed that the lowest vitamin D levels were observed among subjects with both pulmonary tuberculosis and diabetes. Multinomial logistic regression analysis observed that higher levels of vitamin D were protective against both diabetes and pulmonary tuberculosis, and while higher body mass index lowered odds of pulmonary tuberculosis, it increased the odds of diabetes. The cluster analysis identified five distinct clusters with different characteristics of pulmonary tuberculosis, diabetes mellitus, sputum mycobacterial load, age distribution, body mass index, vitamin D, serum albumin, and serum calcium. Conclusion: In South India, among patients with pulmonary tuberculosis and diabetes or either disease alone, hypovitaminosis D is a common phenomenon. The cluster analysis plays an important role in future research on biomarkers to identify specific phenotypes in patients with tuberculosis and diabetes.