ABSTRACT
Objective To detect serum oxytocin and highly sensitive C-reactive protein (hs-CRP) levels in obese and type 2 diabetes mellitus(T2DM) subjects and investigate the relationships between serum oxytocin levels and hs-CRP, glycolipid metabolism, insulin resistance and pancreas β cell function. Methods A total of 176 subjects were enrolled in the study, including 88 patients with newly-diagnosed type 2 diabetes ( T2DM) and 88 subjects with normal glucose tolerance(NGT). NGT and T2DM groups were further divided each into normal weight (NW) and obese(OB) subgroups. Obesity was defined as body mass index(BMI)≥25 kg/ m2 according to the WHO-Western Pacific Region diagnostic criteria (2000). 75g oral glucose tolerance test ( OGTT) was performed in all subjects. Fasting plasma glucose ( FPG), 2 h postprandial plasma glucose (2hPG), fasting insulin ( FINS), 2h postprandial serum insulin(2hINS), HbA1C and lipids were also determined. Insulin resistance and pancreas β-cell function were determined by homeostasis model assessment ( HOMA-IR, HOMA-β). Highly sensitive C-reactive protein(hs-CRP) level was determined by chemiluminescence immunoassay and fasting serum oxytocin level was determined by ELISA. Results Serum oxytocin level was lower in T2DM group than that in NGT group(P<0. 01), while serum hs-CRP level was higher in T2DM group than that in NGT group(P<0. 01). The level of serum oxytocin in subjects with obesity was also lower than that in subjects with NW in both NGT and T2DM groups [7. 16(6. 45-8. 82) vs 7. 98(7. 03-9. 17) ng/ L and 9. 23(8. 16-10. 36) vs 9. 86(8. 77-12. 06) ng/ L, P<0. 05]. The level of serum hs-CRP in subjects with obesity was higher than that in subjects with NW in both NGT and T2DM groups [0. 99(0. 25-1. 97) vs 0. 54(0. 19-0. 91) mg/ L and 3. 47(1. 63-6. 20) vs 1. 65(0. 81-3. 81) mg/ L, P<0. 05]. Serum oxytocin level was negatively correlated with hs-CRP, BMI, WC, WHR, HbA1C , FPG, 2hPG, FINS, 2hINS, total cholesterol, triglycerides, LDL-C and HOMA-IR, while was positively correlated with HOMA-β(P<0. 05). Subjects within the upper serum hs-CRP tertile had lower level of oxytocin when compared to subjects in the middle or lower serum hs-CRP tertiles(P<0. 05 ). Conclusion Serum oxytocin level was decreased in subjects with type 2 diabetes as well as with obesity. Serum oxytocin level was closely correlated with inflammation, glycolipid metabolism, insulin resistance, and pancreas β cell function. It may play an important role in the pathogenesis of obesity and T2DM.