Relationships between preptin and osteocalcin in obese, overweight, and normal weight adults

Preptin is an endocrine peptide secreted from pancreatic beta cells; it acts as a physiological amplifier of glucose-mediated insulin secretion. Osteocalcin, secreted by osteoblasts, is also involved in the regulation of body energy in that it modulates fat and glucose metabolism. The aim of this study was to investigate circulating preptin and osteocalcin levels and the possible association between them in obese and overweight adults. A total of 100 obese-overweight adults and 50 healthy controls matched for age and sex were enrolled in this study. Anthropometric measurements were taken and fasting glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), lipid profile, preptin, and osteocalcin were assessed. Preptin was significantly higher in obese and overweight subjects than in controls, whereas osteocalcin was significantly lower. In multiple regression analysis, preptin was independently influenced by waist circumference (WC) (beta = 3.75, P = 0.03), fasting insulin (beta = 4.77, P = 0.01), HOMA-IR (beta = 8.21, P = 0.003), and osteocalcin (beta = -28.41, P = 0.04). Osteocalcin was independently influenced by body mass index (beta = -1.46, P = 0.05), WC(beta = -2.04, P = 0.03), fasting insulin (beta = -2.69, P = 0.02), HOMA-IR (beta = -0.19, P = 0.006), and triglyceride (beta = -4.54, P = 0.001). In conclusion, elevated serum preptin and decreased osteocalcin concentrations, together with insulin resistance, are associated with obesity and overweight. Serum preptin is also independently associated with osteocalcin, which may explain, at least in part, the crosstalk between bone and the beta cells of the pancreas.