A novel ultra-sensitive enzyme immunoassay for soluble human insulin receptor ectodomain and its measurement in urine from healthy subjects and patients with diabetes mellitus

ObjectiveFor the early identification of patients at risk of developing diabetes mellitus, and to prevent the onset of diabetes by performing dietary counseling and exercise guidance, we have developed an ultra-sensitive immune complex transfer enzyme immunoassay (ICT-EIA) to measure soluble human insulin receptor ectodomain (sIRα) in urine which is collected non-invasively.Design and methodsWe developed ICT-EIA for sIRα and measured urinary sIRα from 106 healthy volunteers, 35 obese volunteers and 42 patients with diabetes.ResultsThe detection limit of ICT-EIA (0.04 pg/mL), using a urine sample of as little as 100 μL, was a few hundred-fold higher than that of conventional ELISA. Using ICT-EIA, the urinary sIRα level in patients with diabetes (9.7 ± 20.1 pg/mg creatinine) was significantly higher than those in healthy volunteers (1.4 ± 0.9; P < 0.001).ConclusionICT-EIA for sIRα may be useful as a good marker for evaluating diabetes risk.