Kong M, Lim YJ, Kim Y, et al. - By retrospectively analyzing the clinical data of radiotherapy-treated lung cancer patients (n = 123), researchers investigated how the development of radiation pneumonitis was influenced by diabetes mellitus (DM) and DM-related serologic factors (HbA1c and fasting glucose) in these patients. They found that in patients with DM and in those without DM, the estimated incidence of grade ≥ 3 radiation pneumonitis was 44.4% and 20.7%, respectively. For HbA1c level ≤ 6.15% and for HbA1c level > 6.15%, the estimates were 12.7% and 41.5%, respectively, for the incidence of grade ≥ 3 radiation pneumonitis. This was estimated to be 17.2% and 35.5% for fasting glucose level ≤ 121 and for fasting glucose level > 121 mg/dL, respectively. Significant predictors for the occurrence of grade ≥ 3 radiation pneumonitis in lung cancer patients were DM, HbA1c, and fasting glucose level. Exercising greater caution while treating patients with DM, patients who have HbA1c > 6.15%, and patients who have fasting glucose > 121 mg/dL is recommended.