Building on cross-sectional research indicating that alcohol consumption decreases endogenous GLP-1 and may contribute to a heightened risk of hypoglycemia post-metabolic surgery, this longitudinal, within-subject study examined whether acute alcohol intake reduced GLP-1 and increased fibroblast growth factor 21 (FGF21)–a liver-derived hormone implicated in glucose regulation and alcohol consumption in animal models –more profoundly after surgery. This evidence concerns the gene GLP1R and Hypoglycemia.