To determine the role of active GLP-1 in plasma on the social isolation-induced obesity and type 2 diabetes, we examined the effects of the ingestion of alogliptin for 3 days on daily food intake, body weight gain, blood glucose levels, and plasma active GLP-1 and Fgf21 levels in individually housed KKAy mice. This evidence concerns the gene FGF21 and obesity due to melanocortin 4 receptor deficiency.