GIP and type 2 diabetes mellitus: However, while the GLP-1R has successfully been exploited for the treatment of type 2 diabetes (T2D), with several pharmacological GLP-1R agonists currently in use clinically or undergoing clinical trials (5), the GIPR has not until recently been intensively pursued as a T2D treatment target, primarily due to GIP responses being blunted in T2D patients (6) and the perception that GIPR activation leads to weight gain, as inferred from the observation that GIPR knockout (KO) mice are protected against the effects of an obesogenic diet (7).