1. Center for Diabetes, Endocrinology and Metabolism, Kansai Electric Power Hospital , Osaka 553-0003 , Japan
2. Yutaka Seino Distinguished Center for Diabetes Research, Kansai Electric Power Medical Research Institute , Kobe 650-0047 , Japan
3. Department of Diabetes, Endocrinology and Metabolism/Department of Rheumatology and Clinical Immunology, Gifu University Graduate School of Medicine , Gifu 501-1194 , Japan