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Insulin resistance and pancreatic ß-cell dysfunction are the main pathogenesis of type 2 diabetes mellitus (T2DM). However, insulin therapy and diabetes medications do not effectively solve the two problems simultaneously. In this study, a biomimetic oral hydrogen nanogenerator that leverages the benefits of edible plant-derived exosomes and hydrogen therapy was constructed to overcome this dilemma by modulating gut microbiota and ameliorating oxidative stress and inflammatory responses. Hollow mesoporous silica (HMS) nanoparticles encapsulating ammonia borane (A) were used to overcome the inefficiency of H2 delivery in traditional hydrogen therapy, and exosomes originating from ginger (GE) were employed to enhance biocompatibility and regulate intestinal flora. Our study showed that HMS/A@GE not only considerably ameliorated insulin resistance and liver steatosis, but inhibited the dedifferentiation of islet ß-cell and enhanced pancreatic ß-cell proportion in T2DM model mice. In addition to its antioxidant and anti-inflammatory effects, HMS/A@GE augmented the abundance of Lactobacilli spp. and tryptophan metabolites, such as indole and indole acetic acid, which further activated the AhR/IL-22 pathway to improve intestinal-barrier function and metabolic impairments. This study offers a potentially viable strategy for addressing the current limitations of diabetes treatment by integrating gut-microbiota remodelling with antioxidant therapies.

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Elevated circulating branched-chain amino acids (BCAA) have been linked with the severity of insulin resistance across numerous populations, implicating heightened BCAA metabolism as a potential therapy for insulin resistance. Recently, the angiotensin II type 1 receptor (AT1R) inhibitor Valsartan (VAL) was identified as a potent inhibitor of branched-chain alpha-keto acid dehydrogenase kinase (BCKDK), a negative regulator of BCAA metabolism. This work investigated the effect of VAL on myotube metabolism and insulin sensitivity under both insulin sensitive and insulin resistant conditions. C2C12 myotubes were treated with or without VAL at 8 µM for 24 h, both with and without hyperinsulinemic-induced insulin resistance. Oxygen consumption and extracellular acidification were used to measure mitochondrial and glycolytic metabolism, respectively. Gene expression was assessed via qRT-PCR, and insulin sensitivity was assessed via Western blot. Insulin resistance significantly reduced both basal and peak mitochondrial function which were rescued to control levels by concurrent VAL. Changes in mitochondrial function occurred without substantial changes in mitochondrial content or related gene expression. Insulin sensitivity and glycolytic metabolism were unaffected by VAL, as was lipogenic signaling and lipid content. Additionally, both VAL and insulin resistance depressed Bckdha expression. Interestingly, an interaction effect was observed for extracellular isoleucine, valine, and total BCAA (but not leucine), suggesting VAL may alter BCAA utilization in an insulin sensitivity-dependent manner. Insulin resistance appears to suppress mitochondrial function in a myotube model which can be rescued by VAL. Further research will be required to explore the implications of these findings in more complex models.

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Background: The correlation between various insulin resistance surrogates and frailty remains under investigation in the scientific community. Methods: Data from NHANES (1999-2018) were used. We utilized weighted binary logistic regression, trend tests, RCS analysis, and subgroup analysis to comprehensively assess the link between METS-IR, HOMA-IR, and TyG, and frailty risk. Results: The results revealed a significant positive association between high levels of METS-IR, HOMA-IR, and TyG with the risk of frailty in all models. Notably, in model 4, the highest quintile of METS-IR showed the strongest link (OR: 2.960, 95% CI: 2.219-3.949), with HOMA-IR (OR: 2.522, 95% CI: 1.927-3.301) following closely behind. Trend tests revealed a positive trend between METS-IR, HOMA-IR, and TyG with the risk of frailty (P for trend < 0.05). RCS analysis showed a linear relationship between METS-IR and the risk of frailty (P for nonlinearity > 0.05). In contrast, HOMA-IR and TyG exhibited a U-shaped nonlinear relationship (P for nonlinearity < 0.05). Conclusion: The research identified a linear association between METS-IR and frailty risk, whereas HOMA-IR and TyG displayed a U-shaped, nonlinear relationship pattern with the risk of frailty. Among the varying levels examined, the linkage between METS-IR and frailty was most pronounced in the top quintile.

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BACKGROUND: Elevated liver enzyme levels have been associated with metabolic syndrome in both obese and non-obese pediatric populations. This study aims to compare the serum liver enzyme levels in obese adolescents with and without insulin resistance (IR). METHODS: A cross-sectional analysis was conducted involving obese adolescents aged 10-18. We assessed somatometry, serum insulin levels, lipid profiles, and liver enzymes (aspartate aminotransferase [AST], alanine aminotransferase [ALT], and gamma-glutamyl transferase [GGT]). Statistical differences between groups were evaluated using Student's t-test or the Chi-squared test, with IR (wIR) status matched by propensity scores based on body mass index (BMI) z-scores. RESULTS: The study included 365 adolescents with obesity, 229 wIR, and 136 without (woIR). Before matching, the wIR group had a significantly higher BMI z-score (2.21 vs. 2.14, p = 0.032). After matching for BMI z-scores (n = 122 each group), the wIR group displayed significantly higher levels of AST (32.3 vs. 24.7, p < 0.001) and ALT (42.4 vs. 30.9, p < 0.001), but no significant differences were observed in GGT levels (37.4 vs. 32.5, p = 0.855). CONCLUSION: Obese adolescent's wIR exhibit higher serum ALT and AST levels, suggesting that altered AST is a potential risk factor for IR.

INTRODUCCIÓN: Se ha observado asociación entre niveles elevados de enzimas hepáticas y síndrome metabólico en población pediátrica con y sin obesidad. El objetivo del estudio fue comparar los niveles séricos de enzimas hepáticas entre adolescentes con obesidad con y sin resistencia a la insulina (RI). MÉTODOS: Se realizó un estudio transversal en adolescentes con obesidad entre 10 y 18 años. Se analizaron los datos somatometricos, insulina sérica, perfil lipídico y niveles de enzimas hepáticas (aspartato aminotransferasa [AST], alanina aminotransferasa [ALT] y gamma-glutamil transferasa [GGT]). Análisis estadístico: se utilizó t de Student o la prueba de Chi-cuadrado para evaluar diferencias entre grupos. Los pacientes con RI se emparejaron con pacientes sin RI utilizando puntuaciones de propensión basadas en la puntuación z del IMC. RESULTADOS: Se incluyeron un total de 365 adolescentes con obesidad (229 con RI y 136 sin RI). El grupo con RI tuvo un IMC mayor (con RI 2.21 vs sin RI 2.14 p = 0.032). Después de emparejar los grupos según el IMCz (n = 122 por grupo), el grupo con RI tuvo niveles de AST (24.7 vs., 32.3, p < 0.001) y ALT (30.9 vs., 42.4, p < 0.001) significativamente más altos en comparación al grupo sin RI. Sin embargo, no hubo diferencia en los niveles de GTT (37.4 vs 32.5, p = 0.855). CONCLUSIONES: Los niveles séricos de ALT y AST en adolescents con obesidad y RI fueron mayores. La AST alterada fue un factor de riesgo para presentar RI.

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Ripened pu-erh tea is known to have beneficial hypoglycemic properties. However, it remains unclear whether the bioactive peptides produced during fermentation are also related to hypoglycemic potential. This study aimed to identify hypoglycemic peptides in ripened pu-erh tea and to elucidate their bioactive mechanisms using physicochemical property prediction, molecular docking, molecular dynamics simulations, and cell experiments. Thirteen peptides were identified by liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS). Among them, AADTDYRFS (AS-9) and AGDGTPYVR (AR-9) exhibited high α-glucosidase inhibitory activity, with half-maximal inhibitory concentration (IC50) values of 0.820 and 3.942 mg/mL, respectively. Molecular docking and dynamics simulations revealed that hydrogen bonding, hydrophobic interactions, and van der Waals forces assist peptides AS-9 and AR-9 in forming stable and tight complexes with α-glucosidase. An insulin-resistance (IR)-HepG2 cell model was established. AS-9 was non-toxic to IR-HepG2 cells and significantly increased the glucose consumption capacity, hexokinase, and pyruvate kinase activities of IR-HepG2 cells (p < 0.05). AS-9 alleviated glucose metabolism disorders and ameliorated IR by activating the IRS-1/PI3K/Akt signaling pathway and increasing the expression levels of MDM2, IRS-1, Akt, PI3K, GLUT4, and GSK3ß genes. In addition, no hemolysis of mice red blood cells red blood cells occurred at concentrations below 1 mg/mL. This work first explored hypoglycemic peptides in ripened pu-erh tea, providing novel insights for enhancing its functional value.

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Insulin resistance is the primary contributor to the disruption in glucose homeostasis in the body, playing a significant causative role in many metabolic diseases. Insulin resistance is characterized by compensatory insulin secretion and reduced insulin responsiveness in target organs. Dysregulation of the interaction between insulin-secreting cells and insulin-responsive target organs is an important factor driving the progression of insulin resistance. Circulating endocrine hormones are important mediators mediating the interaction between insulin-secreting cells and insulin-responsive target organs. In addition to the classical hormones secreted by endocrine glands and organ-specific hormones secreted by metabolism-related organs (adipose tissue, muscle, liver, etc.), extracellular vesicles have been recognized as a novel class of endocrine hormones with a complex composition. Extracellular vesicles can transport signaling molecules, such as miRNAs and LncRNAs, to vital organs related to insulin resistance, in a manner akin to conventional hormones. The significant role in regulating the development of insulin resistance underscores the increasing interest in extracellular vesicles as essential contributors to this process. In this review, we summarize the three types of hormones (classical hormones, organokines and extracellular vesicles) that play a regulatory role in insulin resistance, and focus on the novel endocrine hormones, extracellular vesicles, to elaborate the mechanism of extracellular vesicles' regulation of insulin resistance progress from two aspects: the impact on insulin-secreting cells and the influence on insulin-responsive target organs. In addition, this paper outlines the clinical applications of extracellular vesicles in insulin resistance. A comprehensive understanding of the regulatory mechanisms and diagnostic status of the inter-organ network in insulin resistance has great potential to advance targeted therapeutic interventions and diagnostic markers, thereby benefiting both the prevention and treatment of insulin resistance.

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BACKGROUND: Insulin resistance (IR) is prevalent in individuals undergoing peritoneal dialysis (PD) and is related to increased susceptibility to coronary artery disease and initial peritonitis. In recent investigations, correlations have been found between indices of IR and the incidence of all-cause mortality in various populations. However, such correlations have not been detected among individuals undergoing PD. Hence, the present study's aim was to explore the connections between IR indices and the incidence of all-cause mortality in PD patients. METHODS: Peritoneal dialysis patients (n = 1736) were recruited from multiple PD centres between January 2010 and December 2021. Cox proportional hazards and restricted cubic spline regression models were used to evaluate the connections between the triglyceride-glucose (TyG) index, triglyceride-glucose/body mass index (TyG-BMI), and triglyceride/high-density lipoprotein cholesterol (TG/HDL-C) ratio and the occurrence of all-cause mortality. All three IR indices were integrated into the same model to assess the predictive stability. Furthermore, a forest plot was employed to display the findings of the subgroup analysis of PD patients. RESULTS: Overall, 378 mortality events were recorded during a median follow-up time of 2098 days. Among PD patients, a higher TyG index, TyG-BMI, and TG/HDL-C ratio were identified as independent risk factors for all-cause mortality according to Cox proportional hazards analyses (hazard ratio (HR) 1.588, 95% confidence interval (CI) 1.261-2.000; HR 1.428, 95% CI 1.067-1.910; HR 1.431, 95% CI 1.105-1.853, respectively). In a model integrating the three IR indices, the TyG index showed the highest predictive stability. According to the forest plot for the TyG index, no significant interactions were observed among the subgroups. CONCLUSION: Significant associations were found between the TyG index, TyG-BMI, and TG/HDL-C ratio and the incidence of all-cause mortality among PD patients. The TyG index may be the most stable of the three surrogate IR markers. Finally, a correlation was identified between IR and the risk of all-cause mortality in patients undergoing PD.

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Subjects who have ischemia with non-obstructive coronary arteries (INOCA) experience angina pectoris with evidence of myocardial ischemia but without coronary stenosis. Few studies have investigated factors associated with its survival, especially insulin resistance. In this study, subjects with angina pectoris, without known diabetes mellites (DM), and with non-invasive tests showing myocardial ischemia were admitted for coronary angiography (CAG). Those whose CAG did not reveal stenosis and agreed to receive an oral glucose tolerance test (OGTT) 2 weeks after hospital discharge were enrolled for analysis. All-cause mortality was recorded, which served as the outcome of the study. A total of 587 subjects with INOCA, without known DM, and with OGTT data were analyzed. After OGTT and HbA1c tests, 86 subjects (14.7%) were newly diagnosed with DM and 59.8% had pre-DM. The median duration of follow-up was 7.03 years. Thirty-nine subjects died during the follow-up period. The incidence rate of mortality was 9.9 /1000 person-year. Those who died had a higher fasting glucose (101 ± 17 vs. 94 ± 13 mg/dl, p = 0.003) but a lower estimated glomerular filtration rate (eGFR) (54 ± 22 vs. 87 ± 30 ml/min, p < 0.001). In the Cox survival analysis, a higher fasting glucose (hazard ratio 1.053, p = 0.007) was associated with worse mortality for INOCA without DM (N = 501). On the contrary, a higher eGFR (hazard ratio 0.967, p = 0.012) was protective of better survival for non-diabetic INOCA (N = 501). In conclusion, for non-diabetic INOCA, higher fasting glucose was associated with worse mortality and higher eGFR was protective for better survival.

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Fucoxanthin (Fx) has garnered significant interest due to its exceptional biological properties. However, its efficacy in enhancing food quality and human health is contingent upon the solubility of the compound in water and its physicochemical stability. Therefore, nanocarriers must be developed to enhance the stability and biocompatibility of Fx. In this study, oxidized paramylon and Fx self-assembled nanoparticles (Fx-OEP) were prepared via the anti-solvent method, with a loading rate of 82.47 % for Fx. The Fx-OEP exhibited robust storage and photostability. In vitro simulated digestion assays demonstrated that Fx-OEP effectively protected Fx from premature gastric release, while achieving a release efficiency of 72.17 % in the intestinal phase. Fx-OEP has the capacity to scavenge a range of reactive oxygen species (ROS) induced by cellular oxidative stress. Treatment with Fx-OEP resulted in a significant reduction in ROS accumulation in insulin-resistant HepG2 cells, which was attributed to the activation of the nuclear factor E2-related factor 2/heme oxygenase-1 (Nrf2/HO-1) pathway. This, in turn, activated insulin receptor substrate 1/glucose transporter type 4 (IRS1/GLUT4), promoting cellular glucose absorption and utilization. These findings indicate the potential of self-assembled nanoparticles based on oxidized paramylon as a new type of nanocarrier for delivering hydrophobic substances.

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BACKGROUND: Pre-diabetes is an important risk factor for the development of type 2 diabetes and is common in Nigeria. Effective intervention can reverse the underlying pathogenesis of insulin resistance in pre-diabetes. This study aimed to determine and compare the impact of moderate exercise and metformin interventions on insulin resistance among participants with pre-diabetes. MATERIALS AND METHODS: Using a randomised placebo-controlled design, 54 Nigerians with pre-diabetes were selected using simple random sampling. They were offered metformin, moderate exercise or placebo treatment and followed up for 12 weeks. Insulin resistance was assessed before and after the interventions and the outcome was compared. RESULTS: Forty-nine participants with pre-diabetes completed the study. Participants in both the exercise and metformin groups had significantly decreased insulin resistance compared to placebo after 12 weeks of intervention. However, there was a decrease in insulin resistance by 77.3% (homeostasis model assessment-insulin resistance [HOMA-IR]) and an increase in insulin sensitivity by 81.2% (quantitative insulin sensitivity check index [QUICKI]) in the exercise group. In comparison, participants in the metformin group had a decrease in insulin resistance by 66.3% (HOMA-IR) and an increase in insulin sensitivity by 76.2% (QUICKI). CONCLUSION: Amongst Nigerians with pre-diabetes, both moderate exercise and metformin have significantly higher efficacy than placebo in improving insulin resistance. However, moderate exercise improved insulin resistance more than the metformin intervention. Participants in this study need to be followed up for a longer period to assess the long-term effects of these interventions.

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Adipose tissue (AT) serves as an energy-capacitive organ and performs functions involving paracrine- and endocrine-mediated regulation via extracellular vesicles (EVs) secretion. Exosomes, a subtype of EVs, contain various bioactive molecules with regulatory effects, such as nucleic acids, proteins, and lipids. AT-derived exosomes (AT-exos) include exosomes derived from various cells in AT, including adipocytes, adipose-derived stem cells (ADSCs), macrophages, and endothelial cells. This review aimed to comprehensively evaluate the impacts of different AT-exos on the regulation of physiological and pathological processes. The contents and functions of adipocyte-derived exosomes and ADSC-derived exosomes are compared simultaneously, highlighting their similarities and differences. The contents of AT-exos have been shown to exert complex regulatory effects on local inflammation, tumor dynamics, and insulin resistance. Significantly, differences in the cargoes of AT-exos have been observed among diabetes patients, obese individuals, and healthy individuals. These differences could be used to predict the development of diabetes mellitus and as therapeutic targets for improving insulin sensitivity and glucose tolerance. However, further research is needed to elucidate the underlying mechanisms and potential applications of AT-exos.

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Erythropoietin (EPO) plays a key role in energy metabolism, with EPO receptor (EpoR) expression in white adipose tissue (WAT) mediating its metabolic activity. Here, we show that male mice lacking EpoR in adipose tissue exhibit increased fat mass and susceptibility to diet-induced obesity. Our findings indicate that EpoR is present in WAT, brown adipose tissue, and skeletal muscle. Elevated EPO in male mice improves glucose tolerance and insulin sensitivity while reducing expression of lipogenic-associated genes in WAT, which is linked to an increase in transcription factor RUNX1 that directly inhibits lipogenic genes expression. EPO treatment in wild-type male mice decreases fat mass and lipogenic gene expression and increase in RUNX1 protein in adipose tissue which is not observed in adipose tissue EpoR ablation mice. EPO treatment decreases WAT ubiquitin ligase FBXW7 expression and increases RUNX1 stability, providing evidence that EPO regulates energy metabolism in male mice through the EPO-EpoR-RUNX1 axis.

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BACKGROUND/OBJECTIVES: Insulin resistance (IR)-related disorders and cognitive impairment lead to reduced quality of life and cause a significant strain on individuals and the public health system. Thus, we investigated the effects of insulin resistance (IR), and blood glucose fluctuations on cognitive function under laboratory and free-living conditions, using ecological momentary assessment (EMA). SUBJECTS/METHODS: Baseline assessments included neuropsychological tests and blood analysis. Individuals were classified as either insulin-sensitive (<2) or insulin-resistant (≥2), based on their Homeostatic Model Assessment (HOMA-IR) values. Continuous glucose monitoring (CGM) using a percutaneous sensor was performed for 1 week. Using multiple linear regression, we examined the effects of HOMA-IR and CGM metrics on cognitive domains. Working memory (WM) performance, which was assessed using EMA, 4 times a day for 3 consecutive days, was matched to short-term pre-task CGM metrics. Multilevel analysis was used to map the within-day associations of HOMA-IR, short-term CGM metrics, and WM. RESULTS: Analyses included 110 individuals (mean age 48.7 ± 14.3 years, 59% female, n = 53 insulin-resistant). IR was associated with lower global cognitive function (b = -0.267, P = 0.027), and WM (b = -0.316; P = 0.029), but not with executive function (b = -0.216; P = 0.154) during baseline. EMA showed that higher HOMA-IR was associated with lower within-day WM performance (ß = -0.20, 95% CI -0.40 to -0.00). CGM metrics were not associated with cognitive performance. CONCLUSIONS: The results confirm the association between IR and decrements in global cognitive functioning and WM, while no effects of CGM metrics were observed, making IR a crucial time point for intervention. Targeting underlying mechanisms (e.g., inflammation) in addition to glycemia could be promising to minimize adverse cognitive effects. Registered under https://drks.de/register/de identifier no. DRKS00022774.

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BACKGROUND: The role of fatty acids (FA) in the pathogenesis of insulin resistance and hyperlipidemia is a subject of intensive research. Several recent works have suggested cis-vaccenic acid (cVA) in plasma lipid compartments, especially in plasma phospholipids (PL) or erythrocyte membranes, could be associated with markers of insulin sensitivity and cardiovascular health. Nevertheless, not all the results of research work testify to these beneficial effects of cVA. Therefore, we decided to investigate the relations of proportion of cVA in plasma PL to markers of insulin resistance in hyperlipidemic men. SUBJECTS: In 231 men (median age 50) with newly diagnosed hyperlipidemia, we analyzed basic clinical parameters together with FA composition of plasma PL and stratified them according to the content of cVA into upper quartile (Q4) and lower quartile (Q1) groups. We examined also small control group of 50 healthy men. RESULTS: The individuals in Q4 differed from Q1 by lower plasma insulin (p < 0.05), HOMA-IR values (p < 0.01), and apolipoprotein B concentrations (p < 0.001), but by the higher total level of nonesterified FA (p < 0.01). Both groups had similar age, anthropometrical, and other lipid parameters. In plasma PL, the Q4 group had lower content of the sum of n-6 polyunsaturated FA, due to decrease of γ-linolenic and dihomo-γ-linolenic acids, whereas the content of monounsaturated FA (mainly oleic and palmitoleic) was in Q4 higher. CONCLUSIONS: Our results support hypothesis that plasma PL cVA could be associated with insulin sensitivity in men with hyperlipidemia.

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Metabolic syndrome is a growing concern in developed societies and due to its polygenic nature, the genetic component is only slowly being elucidated. Common mitochondrial DNA sequence variants have been associated with symptoms of metabolic syndrome and may, therefore, be relevant players in the genetics of metabolic syndrome. We investigate the effect of mitochondrial sequence variation on the metabolic phenotype in conplastic rat strains with identical nuclear but unique mitochondrial genomes, challenged by high-fat diet. We find that the variation in mitochondrial rRNA sequence represents risk factor in the insulin resistance development, which is associated with diacylglycerols accumulation, induced by tissue-specific reduction of the oxidative capacity. These metabolic perturbations stem from the 12S rRNA sequence variation affecting mitochondrial ribosome assembly and translation. Our work demonstrates that physiological variation in mitochondrial rRNA might represent a relevant underlying factor in the progression of metabolic syndrome.

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BACKGROUND: Although insulin resistance (IR) is among the most frequent and pathogenically relevant complications accompanying childhood obesity, its role in modulating and exacerbating obesity pathophysiology has not yet been completely clarified. METHODS: To get deeper insights into the interplay between childhood obesity and IR, we leveraged a comprehensive experimental design based on a combination of observational data, in vivo challenge tests (i.e., oral glucose tolerance test), and ex vivo assays (i.e., incubation of erythrocytes with insulin) using a population comprising children with obesity and IR, children with obesity without IR, and healthy controls, from whom plasma and erythrocyte samples were collected for subsequent metabolomics analysis. RESULTS: Children with concomitant IR showed exacerbated metabolic disturbances in the crosstalk between endogenous, microbial, and environmental determinants, including failures in energy homeostasis, amino acid metabolism, oxidative stress, synthesis of steroid hormones and bile acids, membrane lipid composition, as well as differences in exposome-related metabolites associated with diet, exposure to endocrine disruptors, and gut microbiota. Furthermore, challenge tests and ex vivo assays revealed a deleterious impact of IR on individuals' metabolic flexibility, as reflected in blunted capacity to regulate homeostasis in response to hyperinsulinemia, at both systemic and erythroid levels. CONCLUSIONS: Thus, we have demonstrated for the first time that metabolite alterations in erythrocytes represent reliable and sensitive biomarkers to disentangle the metabolic complexity of IR and childhood obesity. This study emphasizes the crucial need of addressing inter-individual variability factors, such as the presence of comorbidities, to obtain a more accurate understanding of obesity-related molecular mechanisms.

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Myostatin inhibition improves insulin sensitivity in preclinical and clinical models; however, studies investigating the relationship between serum myostatin levels and insulin sensitivity are discrepant. Sensitive and specific myostatin LC-MS/MS assays are now available to accurately assess serum myostatin level in vivo. We sought to determine whether higher serum myostatin levels are independently associated with lower insulin sensitivity in adults with overweight/obesity. Participants included 74 adults, 20-65 years old, BMI ≥25 kg/m2 without type 2 diabetes. Appendicular lean mass (ALM) was measured by dual-energy x-ray absorptiometry; visceral adipose tissue (VAT) was measured by computed tomography. Main outcome measures were serum myostatin levels (LC-MS/MS) and insulin sensitivity (Matsuda index). Mean age was 48 ± 12 years, and BMI was 33.1 ± 5.6 kg/m2 (mean ± SD). Men had higher mean serum myostatin levels versus women (8.3 ± 1.9 vs. 7.2 ± 1.9 ng/mL, p = 0.01) and higher serum myostatin levels were associated with higher ALM (R = 0.34, p = 0.003). Higher serum myostatin levels were associated with lower Matsuda index (R = -0.44, p = 0.0004), which remained significant after controlling for BMI, VAT, ALM, and sex. In conclusion, higher serum myostatin levels are independently associated with lower insulin sensitivity in adults with overweight/obesity and may be a marker of or play a mechanistic role in the development of insulin resistance.

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Background: Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of reproductive age and is closely associated with chronic low-grade inflammation and insulin resistance. To clarify the contribution of prepubertal weight gain to the development of insulin resistance in PCOS, we investigated the effects of early postnatal overfeeding on inflammatory and energy-sensing pathways as well as on markers of insulin signaling in the liver of the PCOS rat model. Methods: Obesity induced by overfeeding was achieved by reducing litter size, while the PCOS-like condition was developed by treatment with 5α-dihydrotestosterone (DHT). Western blot and qPCR were used to analyze the expression of pro-inflammatory transcription factors and cytokines, as well as markers of the energy sensing and insulin signaling pathways. Results: The results showed that hepatic insulin sensitivity was impaired only in DHT-treated rats raised in small litters, as evidenced by increased phosphorylation of IRS1 on Ser307 and decreased expression of total IRS1. Postnatal overfeeding stimulated JNK1 activation independent of hyperandrogenemia; nevertheless, the synergistic effect of both factors triggered NLRP3 activation and increased IL1ß expression in the small litter DHT-treated group. This pro-inflammatory state was accompanied by decreased activatory phosphorylation of AMPK and reduced levels of its protein targets. Conclusions: Overfeeding in the early postnatal period leads to a decrease in hepatic insulin sensitivity in the rat model of PCOS, which is associated with decreased activation of AMPK and stimulation of the hepatic NLRP3-IL1ß signaling pathway. Accordingly, the inhibition of NLRP3 activation could provide a basis for the development of new therapeutic strategies for the treatment of insulin resistance in women with PCOS.

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Anthropometric parameters are widely used in the clinical assessment of hypertension, type 2 diabetes, and cardiovascular disease. However, few studies have compared the association between different anthropometric parameters and insulin resistance (IR). This study was aimed at investigating the relationship between 6 indicators, including body mass index (BMI), calf circumference (CC), arm circumference (AC), thigh circumference (TC), waist circumference (WC), waist-height ratio (WHtR), and IR. Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) was used to measure IR. Weighted linear regression was used to assess the relationship between different parameters and IR. The receiver operating characteristic curve (ROC) was employed to compare the strength of the relationship between different anthropometric parameters and IR. A total of 8069 participants were enrolled in our study, including 4873 without IR and 3196 with IR. The weighted linear regression results showed that BMI, CC, AC, TC and WC were significantly correlated with IR, except WHtR. After adjusting for multiple confounding factors, we found that BMI, AC and WC were significantly positively correlated with IR, while TC was significantly negatively correlated with IR. Logistic regression results showed that a larger TC was associated with a decreased risk of IR. In addition, BMI and WC had similar areas under the curve (AUC: 0.780, 95% CI 0.770-0.790; AUC: 0.774, 95% CI 0.763-0.784, respectively), which were higher than TC and AC (AUC: 0.698, 95% CI 0.687-0.710, AUC: 0.746, 95% CI 0.735-0.757, respectively). To our knowledge, this is the first study to report a negative correlation between TC and IR among patients without diabetes mellitus. Therefore, TC may be a new tool to guide public health and a clinical predictor of IR in non-diabetic patients.

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