200 subjects were recruited in this study and divided into six groups for comparison of the serum betatrophin. 70 healthy subjects and 20 healthy young volunteers were enrolled for investigating the role of betatrophin in energy homeostasis and the circadian rhythm. 50 patients with type 2 diabetes were classified into three groups by the stage of diabetic retinopathy. Rank test was used to analyze the correlation between the progression of diabetic retinopathy and circulating betatrophin. Betatrophin were measured by a commercially available enzyme-linked immunosorbent assay and confirmed via Western Blot.