1. Department of Cardiovascular Medicine, Chiba University Graduate School of Medicine, Chiba 260-0856, Japan
2. Department of Cardiovascular Medicine, Saga University, Saga 849-8501, Japan
3. Department of Medical Statistics, Osaka Metropolitan University Graduate School of Medicine, Osaka 545-8585, Japan
4. Department of Cardiovascular Medicine, Imamura General Hospital, Kagoshima 890-0064, Japan
5. Department of Internal Medicine, Chiba Aoba Municipal Hospital, Chiba 260-0852, Japan
6. Diabetes Therapeutics and Research Center, Institute of Advanced Medical Sciences, Tokushima University, Tokushima 770-8503, Japan