Relationship between radiation dose and markers of insulin resistance and inflammation in atomic bomb survivors.

CONTEXT In recent studies of childhood cancer survivors, diabetes has been considered a late effect associated with high therapeutic doses of radiation therapy. Our recent study of atomic bomb (A-bomb) survivors also suggested an association between radiation dose and diabetes incidence, with exposure city and age at exposure as radiation dose effect modifiers. Insulin resistance mediated by systemic inflammation and abnormal body composition has been suggested as a possible primary mechanism for the incidence of diabetes after total body irradiation, however, no studies have examined low-to- moderate radiation exposure (<4 Gy) and insulin resistance in A-bomb survivors. OBJECTIVES To examine the association between radiation dose and markers of inflammation and insulin resistance. METHODS This study investigated 3,152 survivors who underwent a health examination between 2008 and 2012 and who were younger than 15 years at exposure. Multivariate linear regression analyses were used to evaluate the radiation effects on levels of markers of inflammation and insulin resistance. RESULTS Radiation dose was significantly and positively associated with levels of CRP, triglycerides, homeostasis model assessment of β-cell function (HOMA-β), and HOMA of insulin resistance (HOMA-IR) after adjustment for relevant covariates including sex, city, and age at exposure. Adiponectin and HDL cholesterol levels were also associated significantly and negatively with radiation dose. However, city was not a dose modifier of the radiation response on these markers of inflammation and insulin resistance. CONCLUSIONS Insulin resistance might be a possible factor in the radiation related diabetes incidence in the A-bomb survivors.