Interestingly, Hausenloy et al. [27] reported that the cardioprotective effect of GLP-1 for myocardial infarction was glucose-dependent, and GLP-1 and sitagliptin, a DPP4 inhibitor, did not reduce the infarct size with abnormal glucose level of 5 mmol/l, but high glucose level of 11 mmol/l in ex vivo and > 7–8 mmol/l in vivo study. Here, DPP4 is linked to myocardial infarction.