BackgroundEvidence on the role of irisin in insulin resistance is limited and controversial, and pathways between them remain unknown. We aimed to examine the independent effects of circulating irisin and different adiposity measurements, as well as their potential interactions, on insulin resistance. We also aimed to explore possible pathways among circulating irisin, adiposity, glucose and insulin levels and insulin resistance.MethodsA cross-sectional study of 1,115 community- living obese Chinese adults, with data collection on clinical characteristics, glucose and lipid metabolic parameters and circulating irisin levels.ResultsAmong the 1,115 subjects, 667 (59.8 %) were identified as insulin-resistance, and showed significantly decreased serum irisin than their controls (log-transformed irisin: 1.19 ± 2.34 v.s. 1.46 ± 2.05 ng/ml, p = 0.042). With adjustment for potential confounders, elevated circulating irisin was significantly associated with reduced risk of insulin resistance, with adjusted odds ratio per standard deviation increase of irisin of 0.871 (0.765–0.991, p = 0.036). As for different adiposity measurements, body fat percentage, but neither BMI nor waist, was significantly associated with increased risk of insulin resistance (OR: 1.152 (1.041–1.275), p = 0.006). No significant interaction effect between serum irisin and adiposity on insulin resistance was found. A one pathway model about the relationship between serum irisin and insulin resistance fits well (χ2 = 44.09, p < 0.001; CFI–0.994; TLI =0.986; and RMSEA = 0.067), and shows that elevated circulating irisin might improve insulin resistance indirectly through lowering fasting insulin levels (standardized path coefficient = −0.046, p = 0.032).ConclusionsElevated circulating irisin is associated with lower risk of insulin resistance indirectly through lowering fasting insulin.

BackgroundIrisin, an exercise induced myokine, has broad implications for metabolism and energy homeostasis. Available evidence about the association of serum irisin with chronic kidney disease (CKD) is limited.MethodsCross-sectional data on socio-demographic, lifestyle, clinical characteristics and serum irisin were collected for 1,115 community-living obese Chinese adults (waist circumference ≥ 90 cm for men and ≥ 80 cm for women). CKD was defined as estimated glomerular filtration rate less than 60 ml/min per 1.73 m2 and/or the presence of albuminuria. Associations of serum irisin and body composition measurements with CKD were analyzed using multivariable logistic regression.ResultsThe overall prevalence of CKD were 23.1% (26.6% in females and 15.5% in males, p < 0.001). Subjects within quartile 4 group of serum irisin had significantly the lowest prevalence of CKD (22.9%, 22.2%, 28.7% and 18.7% for quartile 1–4 groups, respectively, p = 0.046). With adjustment for potential confounders, compared with those within quartile 1 group of serum irisin, subjects within quartile 4 group showed significantly decreased risk of CKD and marginally decreased risk of albuminuria, with the adjusted odds ratios (ORs, 95% CI) of 0.572 (0.353-0.927, p = 0.023) and 0.611 (0.373-1.000, p = 0.050), respectively. As for body composition measurements, only body fat percentage was significantly associated with both albuminuira and CKD, with ORs (95% CI) of 1.046 (1.002-1.092, p = 0.039) and 1.049 (1.006-1.093, p = 0.025), respectively. No statistically significant interaction effect between serum irisin and body composition measurements on CKD was found.ConclusionsOur results imply that high serum irisin level was associated with reduced risk of CKD, and should be confirmed in future studies. Furthermore, adiposity per se, rather than body weight or body shape, is independently associated with increased risk of CKD. Future studies should examine whether decreasing body fat percentage may prevent or slow CKD.

Serum FGF21 levels were elevated in patients with hyperthyroidism and declined after thionamide treatment. And serum FGF21 level was independently associated with hyperthyroidism.

Objective: To assess the role of neck circumference (NC) in assessing insulin resistance (IR) in polycystic ovary syndrome (PCOS). Design: A cross-sectional study. Setting: University-affiliated hospital. Patient(s): One hundred forty-three women with PCOS were recruited from November 2018 to February 2020. Intervention(s): None. Main Outcome Measure(s): The associations of NC with IR and the cutoff points of NC for IR. Result(s): The prevalence rates of IR were 64.3%. The patients with PCOS with IR had significantly greater values of systolic blood pressure, NC, body mass index, waist-to-hip ratio, waist circumference, fasting blood glucose, fasting insulin, and homeostasis model assessment of insulin resistance (HOMA-IR). Pearson correlation analysis showed body mass index (log-transformed), waist circumference, waist-to-hip ratio, and HOMA-IR (log-transformed) were positively correlated with NC. Multivariable linear regression showed that NC was significantly associated with HOMA-IR (log-transformed), with the standardized regression coefficient of 0.330 with adjustment for potential confounding factors. Furthermore, multivariate logistic regression analyses showed NC was associated significantly with increased risk of IR, with the adjusted odds ratio of 1.423. Additionally, NC was able to identify IR in women with PCOS; the optimal cut-off points was 34.3 cm (Youden index ¼ 0.586). Conclusion(s):Neck circumference is positively associated with IR in women with PCOS. We suggest NC as a novel, simple, practical, and reliable anthropometric measure to be used to predict the risk of IR in patients with PCOS. (Fertil Steril Ò 2021;115:753-60. Ó2020 by American Society for Reproductive Medicine.) El resumen está disponible en Español al final del artículo.

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