BACKGROUND: The risk of developing diabetes mellitus (DM) during treatment with high-dose glucocorticoids is unknown and monitoring of glucose is random in many settings.

OBJECTIVE: To determine incidence of and risk factors for induction of DM during high-dose glucocorticoid therapy of metastatic spinal cord compression (MSCC) in patients referred to radiotherapy. Furthermore, to describe the time course of development of DM.

SUBJECTS AND METHODS: 140 patients were recruited (131 were included in the analysis) with MSCC receiving high-dose glucocorticoid ≥100 mg prednisolone per day were included in a prospective, observational cohort study. The primary endpoint was development of DM defined by two or more plasma glucose values ≥11.1 mmol/L. Plasma glucose was monitored on a daily basis for 12 days during radiotherapy.

RESULTS: Fifty-six of the patients (43%; 95% CI 35-52%) were diagnosed with DM based on plasma glucose measurements during the study period. Sixteen patients, 12% (95% CI 6-18%), were treated with insulin. At multivariate analysis, only high baseline HbA1c predicted the development of insulin-treated DM. An HbA1c-value <39 mmol/mol was associated with a negative predictive value of 96% for not developing DM needing treatment with insulin. The diagnosis of diabetes with need for insulin treatment was made within 7 days in 14 of the 16 (88%; 95% CI 72-100%) patients.

CONCLUSION: The risk of developing DM during treatment with high-dose glucocorticoids in patients with MSCC referred to radiotherapy is high in the first treatment week. Only referral HbA1c predicts the development of DM.