Several observations suggest that the abnormal GLP-1 secretion is most likely a consequence rather than a cause of diabetes, including the study of Knop et al., which attempted to evaluate the reduced incretin effect as a cause or as a consequence, concluding that it is a characteristic consequence of the diabetic state rather than a primary event that leads to T2DM [88]. The gene discussed is GLP1R; the disease is type 2 diabetes mellitus.