Circulating spexin levels are influenced by the glycemic status and correlated with pancreatic beta-cell function in Chinese subjects

Aims Spexin plays a role in regulating glucose metabolism. This study investigated the spexin levels in different glycemic status and its association with insulin secretion in humans.Methods A total of 462 subjects were recruited in this study, including 52 healthy subjects, 106 first-degree relatives (FDRs) of type 2 diabetes mellitus (T2DM), 115 impaired glucose regulation (IGR), 80 newly diagnosed T2DM, and 106 established T2DM. Serum spexin was measured using ELISA. The homeostasis model assessment of insulin resistance (HOMA2-IR) and beta-cell function (HOMA2-beta), and Stumvoll index estimating first- and second-phase insulin secretion were calculated.Results Spexin levels were higher in FDRs [235.53 pg/ml (185.28, 293.95)] and IGR [239.79 pg/ml (191.52, 301.69)], comparable in newly diagnosed T2DM [224.68 pg/ml (187.37, 279.74)], and lower in established T2DM [100.11 pg/ml (78.50, 137.34)], compared with healthy subjects [200.23 pg/ml (160.32, 275.65)]. Spexin levels were negatively correlated with fasting plasma glucose (FPG) (r = - 0.355, P < 0.001), hemoglobin A1C (HbA1c) (r = - 0.379, P < 0.001), and HOMA2-IR (r = - 0.225, P < 0.001), and positively correlated with HOMA2-beta (r = 0.245, P < 0.001) after adjusting for age, sex, and BMI. Multivariate linear regression analysis showed that established T2DM and HOMA2-beta were independently associated with serum spexin levels.Conclusions Serum spexin levels represented as a bell-shaped curve along the glycemic continuum and is closely related with insulin secretion in humans.