In a randomized, double-blind crossover trial of 20 normoglycaemic patients without diabetes and with HF with ischemic heart disease, severe left ventricular impairment, NYHA II, and III, Halbirk et al. [32] found that GLP-1 infusion over 48 h increased circulating insulin levels and reduced plasma glucose concentration but had no major cardiovascular effects in patients with chronic heart failure when compared with a placebo. This evidence concerns the gene GCG and diabetes mellitus.