Endothelial dysfunction is an early event in atherogenesis. The conventional non-invasive methods, measuring flow mediated vasodilation at 1 minute after hyperemic condition, had some limitation. The purpose of this study is to evaluate the usefulness of initial reaction time(IRT) after hyperemic condtion as a new parameter of endothelial function.

Flow-mediated, endothelium-dependent vasodilation (FMD), endothelium-independent vasodilation (EID) and IRT were measured in 12 young diabetic patients(6 male and 6 female, mean age 26.3) and 12 age-matched healthy controls (6 male and 6 female, mean age 25.6), For the measurement of brachial arterial diameter, 7.5MHz ultrasound was used and for the continous monitoring of arterial diameter, specially designed fixing device was applied to the all subjects.

There were no significant difference in BMI (body mass index), mean age and blood pressure between normal control and young diabetic group. The FMD of young diabetic patients was lower than that of age-matched healthy controls (diabetic patients: 6.32.1%, healthy control: 8.92.7%, p<0.05). There was no significant difference in EID between normal control and young diabetic group. The IRT of FMD was significantly shorter in healthy control group than in young diabetic group (healthy control: 20.42.8 sec, diabetic group: 29.55.4 sec, p<0.0001). But IRT of EID showed no significant difference between normal control and young diabetic group. The IRT of FMD showed a significant negative correlation with FMD (r=-0.74, p<0.001) and HDL cholesterol level(r=-0.68, p<0.0001).

These findings strongly suggest that IRT can also be used for early diagnosis of endothelial dysfunction.