Fig. 4

a Insulin doses during the 12-week treatment with vildagliptin, sitagliptin, or linagliptin. The insulin doses at week 0 were not significantly different. The insulin dose in the vildagliptin group was lower than in the sitagliptin group at week 6. The insulin dose in the linagliptin group was lower than in the sitagliptin group at week 6. The mean insulin dose in the vildagliptin group was much lower than in the other two groups at week 12 (P < 0.05). b Insulin changes during the 12-week treatment with vildagliptin, sitagliptin, or linagliptin. There were no significant differences between the three groups at week 6. The insulin changes in the vildagliptin and sitagliptin groups were much more pronounced than in the linagliptin group (P < 0.05). FPG fasting plasma glucose, HbA1c glycosylated hemoglobin, PPG postprandial plasma glucose