Blood glucose level affects iodine-123 labeled MIBG uptake in the lung

The aim of this study was to evaluate the correlation of blood glucose and the metaiodobenzylguanidine (MIBG) uptake in lung and compare the difference between the lung uptake of MIBG in diabetic and non-diabetic patients. Patients who underwent iodine-123 MIBG whole-body scan (WBS) in the Department of Nuclear Medicine Seoul National University Hospital between January 2014 and July 2022 were recruited and analyzed. Semi-quantitative analysis of the mean value of lung-to-mediastinum ratio (LMR) was performed. Correlation was analyzed with Pearson correlation test and mean difference was analyzed with independent t-test. There were 36 patients in diabetic group and 57 patients in non-diabetic group with mean age of 56 ± 14.1 and 52 ± 14.6 years, respectively. The mean 24-h LMRs in diabetic and non-diabetic groups were 1.38 ± 0.20 and 1.17 ± 0.14, respectively. Fasting glucose showed a mean value of 136 ± 37.7 and 96 ± 8.2 mg/dL, respectively. There was a significant positive correlation in diabetic (r = 0.397; P = 0.016) and non-diabetic groups (r = 0.579; P <0.001) with significant mean difference (0.21; P <0.001). In conclusion, lung uptake of MIBG is positively correlated with blood sugar level, with diabetic patients displaying higher lung uptake of MIBG compared with non-diabetic patients. In addition, higher lung uptake of MIBG is evident in patients with higher fasting glucose level and even in non-diabetic patients. Thus, in the situations where MIBG therapy is required, the radiation dose to the lungs must be carefully adjusted for patients with high blood sugar level.