['To analyze the association between the plasma C1q/TNF-related protein-3 (CTRP-3) concentrations, obesity, and type II diabetes in the Chinese population.', 'The plasma CTRP-3 concentrations were analyzed in 174 Chinese subjects with obesity (n\xa0=\xa043), type II diabetes (n\xa0=\xa041), obesity combined with type II diabetes (n\xa0=\xa045), and healthy subjects (n\xa0=\xa045), as were various clinical parameters of obesity-related metabolic disorders and adipokines.', 'The plasma CTRP-3 concentrations were significantly lower in patients with obesity and type II diabetes than in healthy subjects (P\xa0<\xa0.01). Obese type II diabetic patients had the lowest CTRP-3 concentrations. Correlation analysis revealed that the plasma CTRP-3 concentrations were significantly negatively correlated with body mass index, waist circumferences, fasting plasma glucose, 2\xa0h plasma glucose, hemoglobin A1c, triglyceride, fasting insulin, homeostasis model assessment for insulin resistance, and interleukin 6 levels and were positively correlated with high-density lipoprotein cholesterol level (all P\xa0<\xa0.01). Multiple linear regression analysis showed that hemoglobin A1c (β\xa0=\xa0-0.232, P\xa0=\xa0.023), triglyceride (β\xa0=\xa0-0.147, P\xa0=\xa0.040), and homeostasis model assessment for insulin resistance (β\xa0=\xa0-0.172, P\xa0=\xa0.031) were independently correlated with circulating CTRP-3. Multivariate logistic regression analysis revealed that plasma CTRP-3 concentrations were significantly correlated with obesity, even after adjusting for glucose metabolic factors.'] Do plasma CTRP-3 concentrations in Chinese patients with obesity and type II diabetes negatively correlate with insulin resistance?