Changes in C-peptide levels and beta-cell secretory function during the 12-month study period. A: The changes in fasting C-peptide levels and OGTT 2 h postprandial C-peptide levels between baseline and 1, 3, 6 and 12 months. B: Beta-cell secretory function was assessed with HOMA-2B. The results are shown as the mean ± S.D. *P <0.05 compared with pretreatment. HOMA, homeostasis model assessment; OGTT, oral glucose tolerance test.