In liver transplant recipients, new onset of diabetes mellitus (posttransplant diabetes mellitus or PTDM) is estimated to occur in 9% to 21% of recipients. The limited published data on survival and posttransplant complications in liver transplant recipients who develop PTDM show conflicting results. The objective of our study was to compare the morbidity and mortality of 46 patients who developed PTDM with 92 age- and sex-matched patients without pretransplant or posttransplant diabetes mellitus (DM). The demographics of both groups were similar except that there were more blacks with PTDM. The incidence of following complications was higher in the PTDM group compared with the control group: cardiac (48% v 24%; P = .005), major infections (41% v 25%; P = .07), minor infections (28% v 5%; P = .001), neurologic (22% v 9%; P = .05), and neuropsychiatric (22% v 6%; P = .009). Acute rejection was seen more commonly in the PTDM group (50% v 30%; P = .03). The duration of hospital stay, cost of hospitalization, retransplantation rate, and graft survival were similar in both groups. Patient survival also was similar in the PTDM and control groups at 1 year (93.5% v 83.5%), two years (88.1% v 77.9%), and 5 years (75% v 77.2%); Kaplan-Meier survival analysis also did not show survival difference. In conclusion, PTDM was associated with significant morbidity, and our findings suggest that patients with PTDM should be monitored very closely to improve long-term outcome.