GLP-1R agonists lower glycated haemoglobin by about 0.6–1% and induce weight loss. DPP-4 inhibitors reduce glycated haemoglobin by 0.5–0.6% and have no effect on weight. The GLP-1–related drugs arrived in clinical practice with much fanfare and anticipation. DPP- 4 enzyme is a ubiquitous cell-membrane protein, expressed in many tissues, including lymphocytes, which has raised some concerns about the long-term effects of DPP-4 inhibitors, especially on immune function. Data consistent with case reports and animal studies indicate an increased risk for pancreatitis with GLP-1-based therapy and also raise caution about the potential long-term actions of these drugs to promote pancreatic and thyroid cancers. This lecture will review the incretin-based therapies with focus on their benefits and their potential transient and serious side effects.