Abstract: ［Abstract］ Objective〖HTSS〗〓To observe whether application of dexmedetomidine can reduce the oxidative stress response of diabetic patients and reduce the myocardial injury caused by lower limb tourniquet surgery.
〖HTH〗〖WTHZ〗Methods〖HTSS〗〓Eighty patients under general anesthesia were accepted lower limb orthopedic surgery, forty patients with type 2 diabetes, forty patients without diabetes, were randomly divided into four groups using a random number table: diabetes dexmedetomidine group(D1, n=20), nondiabetic dexmedetomidine group(D2, n=20), diabetic nondexmedetomidine group(C1, n=20) and nondiabetic nondexmedetomidine group(C2, n=20). In the test group D1 and group D2，dexmedetomidine 1μg/kg(initial dose) was given(15 min) after induction of anesthesia， followed by continuous infusion at 0.5 μg·kg-1·h-1, until the end of operation. The equal volume of normal saline was given instead of dexmedetomidine in control group C1 and group C2. Before the tourniquet(T0), after loose tourniquet  15 min(T1), 1 h(T2) and 24 h(T3), blood samples were collected for determination of malondialdehyde(MDA), superoxide dismutase(SOD), interleukin1β(IL1β), cardiac troponin I(cTnI) concentrations.
〖HTH〗〖WTHZ〗Results〖HTSS〗〓The concentration of MDA in the four groups were firstly increased at T0~T2 and then decreased at T3, there were statistically significant differences between groups and time points(P＜005), while there was no significant difference between their interactions(P＜005). The SOD were gradually decreased at T0~T2 and then increased at T3, while the levels of IL1β and cTnI were firstly increased at T0~T2 and then decreased at T3 in the four groups, there were statistically significant differences between groups, time points and their interactions(P＜005).
〖HTH〗〖WTHZ〗Conclusion〖HTSS〗〓dexmedetomidine can reduce the oxidative stress response of diabetic patients, reduce the myocardial injury caused by lower limb tourniquet surgery, and produce effective myocardial protection.

Key words: diabetic patients, oxidative stress response, myocardial injury, dexmedetomidine