Background. Diabetes mellitus (DM) is common among patients with schizophrenia. However, information on patients comorbid DM and schizophrenia is limited in China. The present study investigated the prevalence of DM and its clinical characteristics in Chinese inpatients with chronic schizophrenia. Methods. A cross-sectional study was performed in Chinese inpatients with chronic schizophrenia. Diagnosis of Diabetes was established using World Health Organization diagnostic criteria for diabetes mellitus (persistent fasting glucose levels >= 126 mg/dl or 2-h plasma glucose >= 200 mg/dL after a 75-g Oral Glucose Tolerance Test). Patients were also measured height, weight, waist circumference, hip circumference, triglyceride level, and cholesterol level. Patients' psychiatric symptoms were measured by the Positive and Negative Syndrome Scale (PANSS). Binary logistic regression analysis was performed to examine the associated demographic and clinical variables in chronic schizophrenia. Results. A total of 988 inpatients (64.6% male, average age of 47.19 +/- 12.55) was recruited. The prevalence of DM in Chinese patients with chronic schizophrenia was 13.8% (95% CI [11.6-15.9]%). Logistic regression analysis showed that overweight (OR = 1.90, 95% CI [1.20-3.03], p = 0.006), obesity (OR = 1.85, 95% CI [1.07-3.21], p = 0.028), comorbid hypertension (OR = 2.14, 95% CI [1.34-3.42], p = 0.002), and course of schizophrenia (OR = 1.03, 95% CI [1.01-1.06], p = 0.040) were significantly associated with the DM risk in patients with schizophrenia. Conclusion. The findings indicated that diabetes mellitus was non-negligible in patients with chronic schizophrenia. Patients with schizophrenia should be regularly monitored for DM. Overweight/obesity, long duration of schizophrenia, and comorbid hypertension possibly were risk factors for diabetes.