Association of oxytocin with insulin resistance and highly sensitive C-reactive protein in patients with newly diagnosed type 2 diabetes

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. (Chin J Endocrinol Metab, 2015, 31: 481-485) Key words: Oxytocin; Obesity; Diabetes mellitus, type 2; Inflammation