Decreased Circulating Levels of Oxytocin in Obesity and Newly Diagnosed Type 2 Diabetic Patients

CONTEXT AND OBJECTIVE: Oxytocin can affect energy homeostasis and has interesting potential as a metabolic disease therapeutic. We detected serum oxytocin levels in obese (OB) and type 2 diabetes mellitus (T2DM) subjects and investigated the relationships between serum oxytocin levels and glycolipid metabolism, insulin resistance, pancreatic β-cell function, and inflammation. PATIENTS AND METHODS: A total of 176 subjects were enrolled in the study, including 88 patients with newly diagnosed T2DM and 88 subjects with normal glucose tolerance (NGT). NGT and T2DM groups were divided into normal-weight (NW) and OB subgroups. We analyzed the concentrations of oxytocin by ELISA. Oral glucose tolerance testing was done, and hemoglobin A1c (HbA1c), blood lipids, and highly sensitive C-reactive protein (hs-CRP) were also measured. Insulin resistance and pancreatic β-cell function were assessed by homeostasis model assessment (HOMA). RESULTS: Serum oxytocin levels were lower in the T2DM group than in the NGT group (P < .01). The levels of serum oxytocin in OB subjects were also lower than those in NW subjects (P < .01). Serum oxytocin levels were negatively correlated with body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR), HbA1c, fasting plasma glucose (FPG), 2-hour plasma glucose, fasting insulin (FINS), 2-h insulin, total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), HOMA of insulin resistance (HOMA-IR), and hs-CRP and positively correlated with HOMA of β-cell function (HOMA-β) (P < .05). Multiple stepwise regression analysis showed that 2-hour plasma glucose, BMI, and TC were associated with serum oxytocin levels (P < .05). Logistic regression analyses demonstrated that serum oxytocin was significantly associated with T2DM (P < .01). CONCLUSIONS: Serum oxytocin levels were decreased in T2DM as well as OB subjects.