The present invention relates to methods of identifying whether one or more candidate compounds is a modulator of a G protein-coupled receptor (GPCR) or a modulator of blood glucose concentration. In certain embodiments, the GPCR is human. The present invention also relates to methods of using a modulator of the GPCR. A preferred modulator is agonist. Agonists of the invention are useful as therapeutic agents for lowering blood glucose concentration, for preventing or treating certain metabolic disorders, such as insulin resistance, impaired glucose tolerance, and diabetes, and for preventing or treating a complication of an elevated blood glucose concentration, such as atherosclerosis, heart disease, stroke, hypertension and peripheral vascular disease.
