Abstract 3303: Heart and Skeletal Muscle Insulin Resistance but not Myocardial Perfusion can be Improved by Chronic Troglitazone Therapy in Type II Diabetics
(Background) Heart and skeletal muscle insulin resistance and abnormal myocardial perfusion have been reported in type 2 diabetics. Acute effects of thiazolidione to improve heart and skeletal muscle insulin resistance have been reported in type 2 diabetics with coronary artery disease. However chronic effects of thiazolidiones on heart and skeletal muscle insulin resistance and myocardial perfusion in type 2 diabetics remain uncertain.
(Methods) To test the hypothesis whether chronic therapy with thiazolidione can improve heart and skeletal muscle insulin resistance and change myocardial perfusion response to dipyridamole in type 2 diabetics without coronary artery disease, rest and dipyridamole stress positron emission tomography using 13N-ammonia and heart and skeletal muscle positron emission tomography with [18F]2-fluoro-2-deoxy-D-glucose under insulin clamping were undertaken before and 12 month after the initiation of troglitazone therapy (400 mg/day) in 23 type 2 diabetics without coronary artery disease. Data were expressed as mean value and standard deviation (SD).
(Results) Baseline myocardial blood flow (ml/min/100 g) was comparable before and after the therapy (pre: 77.5 (SD 11.6) vs. post: 74.5 (SD 9.62)). Myocardial blood flow during dipyridamole stress in type 2 diabetics before the therapy (178 (SD 50.9)) was not significantly changed after the therapy (184 (SD 61.2), p=NS). Myocardial flow reserve in type 2 diabetics was not improved by troglitazone (baseline 2.23 (SD 0.84) vs. post-therapy 2.27 (SD 0.90), p=NS). After troglitazone therapy, glucose disposal rate (micromole/min/kg) (pre; 19.0 (SD 9.55), post; 28.7 (SD 15.3)) significantly improved (p<.05) as did the skeletal muscle glucose utilization rate [micromole/min/kg] (pre; 20.3 (SD 11.8), post; 34.8 (SD 10.7), p<.05). Myocardial glucose utilization rate [micromole/min/kg] was also significantly improved by troglitazone (pre; 340 (SD 105) vs. post; 410 (SD 193), p<.05).
(Conclusions) Chronic thiazolidione therapy with troglitazone improved heart and skeletal muscle insulin resistance but did not change myocardial perfusion including myocardial blood flow response to dipyridamole in type 2 diabetics without coronary artery disease.