GCG and familial long QT syndrome: Interestingly, certain mutations, for example, in the gene encoding Kv11.1 voltage-gated K+ channels cause long-QT syndrome 2 and simultaneously increase the production of GLP-1 by intestinal L cells.23 The data obtained in this study suggest that increased circulating GLP-1 in long-QT syndrome 2 may potentially be antiarrhythmic.