Author(s)

Ikuo Yokoyama, Toshiyuki Moritan, Yusuke Inoue

Department of Cardiovascular Medicine, Clinical Research Center, Sanno Hospital and Sanno Medical Center, International University of Health and Welfare, Tokyo, Japan.
Department of Clinical Engineering, Faculty of Medical Engineering, Suzuka University of Medical Science, Suzuka, Japan.
Department of Radiology, Graduate School of Medicine, Kitasato University, Sagamihara, Japan.

Heart and skeletal muscle insulin resistance and abnormal myocardial flow reserve (MFR) occurs in patients with type-II diabetes. Improvement of heart and skeletal muscle insulin resistance with rosiglitazone use over 16 weeks have been reported. However, it is not clear whether chronic use of troglitazone can improve heart and skeletal muscle insulin resistance and MFR. Materials and Methods: To test the hypothesis whether effects of troglitazone on heart and skeletal muscle insulin resistance and MFR in patients with type-II diabetes, rest and dipyridamole stress perfusion positron emission tomography (PET) with ¹³N-ammonia and heart and skeletal muscle ¹⁸FDG PET scans under insulin clamping were undertaken before and 12 month after the initiation of troglitazone therapy (400 mg/day) in 23 patients with type-II diabetes. Twenty patients with type-II diabetes without CAD and without medications were served as controls. In controls, any medications were not added from the first PET study and 12 months after the second PET study. Results: Baseline myocardial blood flow (MBF) was comparable before and after the troglitazone group as was the controls. MBF during dipyridamole administration (0.56 mg/min/kg) was not significantly improved in troglitazone group and controls. MFR was not improved in troglitazone group and controls. In troglitazone group, whole body glucose disposal rate (GDR; μmole/min/kg) significantly improved (pre; 19.0 ± 9.55, post; 28.7 ± 15.3, p < 0.05) as did the skeletal muscle glucose utilization rate (SMGU (μmole/min/kg); pre; 20.3 ± 12.0, post; 34.8 ± 10.6, p < 0.05) and the myocardial glucose utilization rate (MGU (μmole/min/kg); pre; 339.7 ± 105.2 vs. post; 410.0 ± 240.0, p < 0.05). GDR, SMGU and MGU were unchanged in controls. Conclusions: Troglitazone can improve heart and skeletal muscle insulin resistance in patients with type-II diabetes but not MFR showing that co-existence of heart and skeletal muscle insulin resistance is implicated in patients with type-II diabetes and impaired MFR is uncoupled with insulin resistance in the whole body and heart and skeletal muscle in patients with type-II diabetes.

Insulin Resistance; Myocardial Insulin Resistance; Glucose; FDG; PET; Type-II Diabetes; Flow Reserve

Yokoyama, I. , Moritan, T. and Inoue, Y. (2013) Heart and skeletal muscle insulin resistance but not myocardial blood flow reserve could be related to chronic use of thiazolidione in patients with type-2 diabetes. Journal of Biomedical Science and Engineering, 6, 144-151. doi: 10.4236/jbise.2013.62018.