1. Department of Diabetes, Endocrinology and Metabolism, Division of Internal Medicine, Shinshu University School of Medicine , Matsumoto 390-8621 , Japan
2. Takeda Internal Medicine Clinic , Azumino 399-8304 , Japan
3. Miyamoto Internal Medicine Clinic , Matsumoto 390-0848 , Japan
4. Center for Clinical Research, Shinshu University Hospital , Matsumoto 390-8621 , Japan
5. Faculty of Pharmaceutical Sciences, Teikyo Heisei University , Nakano 164-8530 , Japan