Effects of ionizing radiation on impairments of glucose and lipid metabolism and impact on risks of arteriosclerotic diseases and cancers

Summary

Impairment of glucose metabolism and lipid metabolism are major risk factors for arteriosclerotic diseases, but the effects of atomic bomb radiation on those conditions are unclear. The Adult Health Study (AHS) cohort of atomic bomb survivors, which has been followed by biennial health examinations since 1958 and has obtained medical information at each examination cycle, is comprised of suitable subjects for assessing the effects of radiation on conditions such as diabetes and dyslipidemia. Furthermore, the AHS cohort was expanded in 2008 to include about 1,900 younger survivors (10 years old at the time of bombing [ATB]), and various biomarkers for glucose and lipid metabolism have been measured in them as well as in the original cohort. Since the expansion group includes a large number of lightly exposed individuals relative to the original cohort, it will provide more precise information on dose response. In this proposed research protocol (RP), we will use a longitudinal study format to examine whether radiation exposure is associated with the development of diabetes and whether any such association is influenced by the city of exposure and age ATB.

It is well known that radiation exposure is associated with increased risk for many cancers. Recent studies have also suggested an association between radiation exposure and the risk of arteriosclerotic diseases; however, the underlying mechanism remains elusive. Diabetes and dyslipidemia are major risk factors for arteriosclerotic diseases. Recent epidemiological studies have also shown that diabetes is associated with risk for not only arteriosclerotic diseases but some cancers as well. This RP will also investigate whether radiation exposure is associated with increased risks of arteriosclerotic disease and cancer through impaired glucose and/or lipid metabolism, using ‘causal modeling’ to evaluate intermediate variables. We will use a cross-sectional study design, to investigate an association between radiation exposure and HbA1c, insulin resistance, lipid levels (such as HDL cholesterol), and biomarkers involving glucose and lipid metabolism (such as adiponectin).

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