1. Barbara Davis Center for Diabetes, University of Colorado Denver , Aurora, Colorado 80045 , USA
2. Biomedical Research Center, Kitasato Institute Hospital, Kitasato University , Tokyo 108-8642 , Japan
3. Diabetes Center, Kitasato Institute Hospital, Kitasato University , Tokyo 108-8642 , Japan
4. Health Promotion Team, ORIX Group Health Insurance Society, ORIX Corporation , Tokyo 105-6135 , Japan
5. Department of Endocrinology and Metabolism, Clinical Medicine Research Center, Sanno Medical Center, International University of Health and Welfare , Tokyo 107-8332 , Japan