1. Department of Diabetology and Metabolism, National Hospital Organization Okayama Medical Center, Okayama 701-1192, Japan
2. Department of Respiratory Medicine, National Hospital Organization Okayama Medical Center, Okayama 701-1192, Japan
3. Department of Pathology, National Hospital Organization Okayama Medical Center, Okayama 701-1192, Japan
4. Division of Diabetology and Endocrinology, Hosogi Hospital, Kochi 780-8535, Japan