The aim of this study was to investigate the prevalence and associated factors of glucocorticoid-induced diabetes mellitus (GDM) in patients with systemic lupus erythematosus (SLE) receiving high-dose glucocorticoid therapy. Patients with SLE who had received high-dose glucocorticoid therapy (prednisolone ≥1 mg/kg/day) at Yonsei University Medical Center, Seoul, Korea, were recruited between January 1999 and June 2009. In total 127 patients with SLE were evaluated. Sixteen (12.6%) of them developed GDM after high-dose glucocorticoid therapy (95% confidence interval, 6.8-18.4%). Univariate analysis showed that old age, family history of diabetes mellitus (DM), hypertension, higher body mass index, higher mean dose of prednisolone before high-dose glucocorticoid therapy, and concurrent use of mycophenolate mofetil (MMF) were factors that would increase the likelihood of GDM. Multivariate analysis determined that age, family history of DM, mean dose of prednisolone before high-dose glucocorticoid therapy and concurrent use of MMF were independent associated factors for GDM. In summary, GDM was developed among 12.6% of patients with SLE after high-dose glucocorticoid therapy. Old age, family history of DM, higher mean dose of prednisolone before high-dose glucocorticoid therapy and concurrent use of MMF were determined to be factors responsible for increasing the risk of developing GDM.