A retrospective study was performed on all liver transplant recipients from British Columbia from 1989 to March 2000 to determine the prevalence and predictive factors of diabetes mellitus (DM) post-liver transplantation. DM was defined as hyperglycemia requiring treatment with insulin or oral hypoglycemic agents. Patient characteristics, cause of liver disease at transplantation, and immunosuppression regimen were considered. Both univariate and multiple logistic regression analyses were performed. Posttransplantation DM (PTDM) occurred in 43 of 177 transplant recipients (24%). Of these, 13 transplant recipients had DM pretransplantation, whereas 30 patients developed de novo PTDM. The majority of patients were treated with insulin (80%). In univariate analysis, transplantation for hepatitis C virus (HCV) liver disease was associated with a greater incidence of PTDM (odds ratio [OR], 3.01; 95% confidence interval [CI], 1.46 to 6.23) and de novo PTDM (OR, 5.20; 95% CI, 2.25 to 11.99). Patients administered tacrolimus had a greater incidence of PTDM (OR, 2.04; 95% CI, 1.01 to 4.13), and there was a trend toward increased PTDM in older patients (mean age, 49 years). Recipient sex, steroid dosage, and acute rejection were not predictive of PTDM. The incidence of graft loss and death rates were similar between the two groups. On logistic regression, HCV was the only independent predictor of PTDM (OR, 4.12; 95% CI, 1.91 to 8.90) and de novo PTDM (OR, 6.02; 95% CI, 2.55 to 14.20). In conclusion, DM post-liver transplantation is a common occurrence and is associated with HCV.