BACKGROUND: Diabetes mellitus (DM) increases the risk of active tuberculosis (TB) and worsens TB outcomes, putting TB control in jeopardy especially in TB endemic countries with rising DM prevalence rates. We assessed DM status and clinical correlates in TB patients across settings in Indonesia, Peru, Romania and South Africa. METHODS: Age-adjusted DM prevalence was estimated using laboratory glycated haemoglobin (HbA1c) or fasting plasma glucose (FPG) in TB patients. Detailed and standardized socio-demographic, anthropometric and clinical measurements were made. Characteristics of TB patients with or without DM were compared using multi-level mixed effect regression models with robust standard errors. RESULTS: Of 2185 TB patients (median age 36.6 years, 61.2% male, 3.8% human immunodeficiency virus–infected), 12.5% (267/2128) had DM, one third of whom were newly diagnosed. Age-standardized DM prevalence ranged from 10.9% (South Africa) to 19.7% (Indonesia). Median HbA1c in TB–DM patients ranged from 7.4% (Romania) to 11.3% (Indonesia). Compared to those without DM, TB–DM patients were older and had a higher body mass index (BMI) (P value < .05). Compared to those with newly diagnosed DM, TB patients with diagnosed DM had higher BMI and HbA1c, less severe TB, and more frequent comorbidities, DM complications, and hypertension (P value < .05). CONCLUSIONS: We show that DM prevalence and clinical characteristics of TB–DM vary across settings. Diabetes is primarily known but untreated, hyperglycemia is often severe, and many patients with TB–DM have significant cardiovascular disease risk and severe TB. This underlines the need to improve strategies for better clinical management of combined TB and DM.