Diabetes mellitus is often complicated by acute or chronic infections, as it is a secondary immune deficiency disorder. Diabetes mellitus produces immune alterations of both cellular and humoral immunity. Tuberculosis in diabetes mellitus is 2-5 times higher. Chances of recurrence with multidrug resistant bacteria are common. More cavitary lesions, less sputum positivity and with relative paucity of symptoms and signs are the features. Treatment for diabetes mellitus should be done with insulin. Every diabetic person should be screened for tuberculosis and every tuberculosis patient should also be searched for diabetes.