Objective: The objective was to evaluate the 30-day re-admission predictive performance of the HOSPITAL score and Diabetes Early Re-admission Risk Indicator (DERRI™) in hospitalized diabetes patients. Methods: This was a case-control study in an academic, tertiary center in the United States. Adult hospitalized diabetes patients were randomly identified between January 1, 2014, and September 30, 2017. Patients were categorized into two groups: (1) re-admitted within 30 days, and (2) not re-admitted within 30 days. Predictive performance of the HOSPITAL and DERRI™ scores was evaluated by calculating receiver operating characteristics curves (c-statistic), Hosmer-Lemeshow goodness-of-fit tests, and Brier scores. Results: A total of 200 patients were included (100 re-admitted, 100 non-re-admitted). The HOSPITAL score had a c-statistic of 0.731 (95% confidence interval [CI], 0.661 to 0.800), Hosmer-Lemeshow test P = .211, and Brier score 0.212. The DERRI™ score had a c-statistic of 0.796 (95% CI, 0.734 to 0.857), Hosmer-Lemeshow test P = .114, and Brier score 0.212. The difference in receiver operating characteristic curves was not statistically significant between the two scores but showed a higher c-statistic with the DERRI™ score (P = .055). Conclusion: Both HOSPITAL and DERRI™ scores showed good predictive performance in 30-day re-admission of adult hospitalized diabetes patients. There was no significant difference in discrimination and calibration between the scores. Abbreviations: CI = confidence interval; DERRI™ = Diabetes Early Re-admission Risk Indicator; IQR = interquartile range.