Development of glucose intolerance over 19 weeks of liraglutide treatment. (a) Weight change over 19 weeks of liraglutide administration. Blood glucose profile after glucose challenge during liraglutide treatment (b) before, (c) 7 weeks, (d) 14 weeks and (e) 19 weeks after the beginning of liraglutide treatment. (f) Area under curve analyses for IPGTT results at different timepoints. (g) Langerhans islet mass and (h) Langerhans islet mass/body weight ratio after 19 weeks of liraglutide treatment. (i) Insulin tolerance test with 1U/kg human insulin after 18 weeks of liraglutide treatment. The data were compared using repeated measures ANOVA or one-way ANOVA followed by Tukey’s HSD tests; *p < 0.05, **p < 0.01, ***p < 0.001 compared to (same-age) WT saline-treated animals. ###p < 0.001 compared to same-age Wfs1 KO liraglutide-treated animals. The data are presented as the mean ± SEM, n = 12–15 (weight and IPGTT), n = 6–8 (ITT), n = 4–6 (islet measurements).