Background: Systolic and diastolic dysfunction without coronary artery disease is well documented in insulin dependent diabetes mellitus. Insulin administration may be a factor influencing vascular and left ventricular function. To evaluate the acute effect of insulin administration and glycemic control using more sensitive methods, we investigated the changes of tissue Doppler parameters during the early periods of glycemic control in uncontrolled NIDDM patients. Methods: 8 uncontrolled NIDDM patients were enrolled for the baseline and follow up echocardiographic examinations at admission and at discharge, respectively. Tissue Doppler signals obtained at 8 mid-septal segments and 2 mid-lateral segments. Peak systolic and diastolic velocities, peak systolic strain, peak systolic strain rate, relative wall thickness, transmitral flow was examined. Results: Age was 64.79.9. Baseline fasting blood sugar was 253.6166.7mg/dL and hemoglobin A1C was 10.32.6mg/dL. Mean follow up period was 5.61.9day. LV diastolic dimension was increased(4.430.75 vs 4.890.67cm, p=0.06) and the changes of relative wall thickness was not significant(0.370.06 vs 0.340.05cm,=0.19). Peak systolic velocity(3.531.09 vs 2.680.66cm/sec, p=0.02) and diastolic A��� velocity were decreased(-5.351.66 vs -3.951.36cm/sec, p=0.02). Peak systolic strain and strain rate were not changed significantly(-16.56.6 vs -18.46.6%, p=0.5, -1.350.62 vs -1.540.62, p=0.5, respectively). Transmitral flow parameters and E/E��� was not changed significantly. Conclusion: Tissue Doppler parameters successfully detected changes of LV function during the early phase of glycemic control. Effects of insulin and decreased blood glucose can contributed to these changes but the increased LV diastolic dimension strongly suggests that intravascular volume status is an important confounder.