1. Department of Rheumatology, Endocrinology and Nephrology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University , Sapporo 060-8638 , Japan
2. Jiyugaoka Medical Clinic , Obihiro 080-0016 , Japan
3. Division of Diabetes and Endocrinology, Department of Medicine, Hakodate Central General Hospital , Hakodate 040-8585 , Japan
4. Sapporo Diabetes and Thyroid Clinic , Sapporo 060-0807 , Japan
5. Kurihara Clinic , Sapporo 004-0053 , Japan