Diabetes mellitus (DM) is known to increase the risk of tuberculosis (TB) and adversely affect TB treatment outcomes. A descriptive study was carried out in registered TB patients screened for DM at Lok Nayak Hospital, New Delhi, India. Of 458 TB patients, 66 (14%) had DM. In those with dual disease, age ⩾40 years, smear-positive pulmonary TB and recurrent TB were significantly more common. There was no effect of DM on TB treatment outcomes, although there was a trend towards smear non-conversion at 2 months. Screening for DM works well, and certain patient characteristics are more common in those with dual disease. AFFILIATIONS 1 Lok Nayak Chest Clinic