OBJECTIVES: High dose glucocorticoid as a part of the treatment of non-Hodgkin's lymphoma was found to induce diabetes in these patients. The present study aims to investigate the incidence and risk factors of glucocorticoid-induced diabetes mellitus (GDM) in Hong Kong. This study also aims to study the influence of GDM on the outcome and effect of chemotherapy on glycemic control. METHODS: Patients without history of diabetes aged 18 or above with confirmed diagnosis of diffuse large B-cell lymphoma (DLBCL) treated with any steroid-containing chemotherapy with or without rituximab between 2009 and 2014 at the Prince of Wales Hospital, were analyzed retrospectively. GDM diagnosis was defined based on the definition of DM according to the American Diabetes Association (ADA). These include a fasting plasma glucose ≥7mmol/L or HbA1c ≥6.5%. Binary logistic regression was used to identify possible significant risk factors of GDM. Diabetic patients treated for DLBCL were also identified and their medications before and after chemotherapy were recorded. Self-reported side effects were also recorded. RESULTS: Among the 78 patients included in the study, 5 developed GDM (6.4%). Steroid administration prior to glucocorticoid-containing chemotherapy was the only significant risk factor associated with GDM development by univariate analysis. Gender, old age, smoking history, overweight, hypertension, dyslipidemia, and pre-diabetes prior to chemotherapy were not found to be significantly associated with GDM development. None of the GDM patients received treatment for hyperglycemia. Two diabetic patients had changes in the original anti-diabetic medications and another 2 required the addition of insulin for glucose control. The most common glucocorticoid-related side effects reported were weight gain and nausea. CONCLUSIONS: The incidence of GDM was found to be 6.4%. Diabetic control may also be worsened in diabetic patients during chemotherapy. These patients may be considered to have more frequent plasma glucose monitoring during chemotherapy.