When directly compared, FGF-23 levels were lower in patients treated with GLP-1 analogues than in those who were not treated with GLP-1 analogues (71 (57–86) vs. 80 (60–98) ng/L, P = 0.01) (Fig. 1a) and in patients without signs of peripheral neuropathy compared to those with peripheral neuropathy (70 (57–85) vs. 80 (57–97) ng/L, P = 0.03) (Fig. 1b). The gene discussed is GCG; the disease is peripheral neuropathy.