[Immunoassays for the incretin hormones GIP and GLP-1].

Immunoassays for incretin hormones, GLP-1 and GIP are critical to study their secretion and DPP-4-processing in vivo, as well as to evaluate therapeutic efficacies of current and future incretin-based drugs in patients with diabetes. However, large variability in levels of incretins, especially intact GLP-1, determined by various immunoassays hampers our understanding of the incretin biology. Recent studies have revealed an importance of an ethanol or solid-phase extraction prior to immunoassays for intact GLP-1. The extraction removes interferences with unknown identity from plasma to obtain results less variable among different subjects. The extraction improves correlation across the different immunoassays for intact GLP-1. Here, we summarize current knowledge and potential problems regarding immunoassays for GLP-1 and GIP.