C1q/TNF-related protein-6 is associated with insulin resistance and the development of diabetes in Chinese population.

AIMS: C1q/tumor necrosis factor-related protein-6 (CTRP6) is a novel adipokine and has emerged as an important mediator for lipid and glucose metabolism. However, to date, the relationship between CTRP6 and T2DM in humans has not been demonstrated. Our objective is to investigate the association of circulating CTRP6 with T2DM in a cross-sectional study.

METHODS: 118 patients with newly diagnosed T2DM, 98 subjects with impaired glucose tolerant (IGT) and 132 healthy subjects were recruited for this study. OGTT were performed in 48 healthy individuals to investigate the association of CTRP6 with glucose, insulin and other adipokines. Circulating CTRP6, TNF-α and Adipoq were measured by ELISA.

RESULTS: IGT and T2DM individuals had higher serum CTRP6 levels than healthy controls (406.2 ± 136.6 and 539.1 ± 169.7 vs. 354.3 ± 117.2 ng/mL; both P < 0.01), whereas serum CTRP6 concentrations were further increased in T2DM patients compared with IGT individuals (P < 0.01). Serum CTRP6 levels were found to be related positively to BMI, WHR, FAT%, TC, TG, HbA1c, FBG, 2 h-OGTT, fasting insulin (FIns), 2 h-Ins, HOMA-IR and TNF-α, and negatively with HDL-C and Adipoq in all individuals (P < 0.05 or P < 0.01). Multivariate logistic regression analysis demonstrated that CTRP6 was correlated with both IGT and T2DM. After an oral glucose challenge, serum CTRP6 concentrations exhibited a similar change with blood glucose, insulin, TNF-α and Adipoq.

CONCLUSIONS: CTRP6 may be a metabolism- and nutrition-related adipokine and may be related to insulin resistance and T2DM.

TRIAL REGISTRATIONS: Clinical Trial Registration Number: ChiCTR-OCC-11001422. Registration name: Plasma cytokines and endothelial function in type 2 diabetes.