The Ffar knock-out mouse was used to test the effects of FFAR2 on insulin secretion. Phenotyping shows no differences for glucose homeostasis on normal or high-fat diet (HFD); marginally significant defect in insulin secretion during hyperglycemic clamps; diminished GSIS from islets under high-glucose conditions; on HFD, gains less weight than WT controls, has improved glucose control and lower HOMA index, and has higher energy expenditure accompanied by higher core body temperature.