Muskeln als Zuckerspeicher: warum Kraft für den Stoffwechsel zählt

The influence of protein intake on insulin resistance, has garnered an increasing amount of interest over the past few decades. Increased provisions of dietary protein during weight loss helps preserve skeletal muscle, which as the largest organ in the human body, is responsible for 80% of insulin-stimulated glucose disposal. The postprandial influence of essential amino acids (EAAs) either alone or as part of intact proteins are regulated through leucine-induced activation of mammalian target of rapamycin (mTOR) that serves to promote muscle protein synthesis and maintain skeletal muscle. High protein diets and/or EAA supplementation have also been demonstrated to improve satiety and augment mitochondrial function, which may have an indirect or direct influence on insulin sensitivity. On the other hand, chronic elevations in postabsorptive concentrations of branched chains amino acids (BCAAs) have been associated with chronic activation of the mTOR pathway, impairing insulin action. It appears that causal links between BCAAs and the pathogenesis of insulin resistance are reliant on chronic hyperinsulinemia and nutrient overload that foster chronic lipotoxicity. Conversely, postprandial elevations in EAAs leverage sensing as an anabolic mediator to facilitate muscle remodeling, augment satiety and improve metabolic regulation.

Insulin resistance develops when skeletal muscle (SM), adipose tissue (AT), and the liver fail to respond adequately to insulin, a dysfunction closely intertwined with chronic low-grade inflammation. This combination leads to compensatory hyperinsulinemia, dysglycemia, and metabolic stress, driving major disorders such as type 2 diabetes, metabolic syndrome, metabolic dysfunction-associated steatotic liver disease (MASLD), and cardiovascular disease. Both adipokines and myokines are central modulators of this metabolic-inflammatory axis. In obesity, diabetes, MASLD, and thyroid dysfunction, alterations in myokines such as myostatin, irisin, fibroblast growth factor 21 (FGF-21), apelin, brain-derived neurotrophic factor (BDNF), interleukin-6 (IL-6), and interleukin-15 (IL-15) influence glucose uptake, lipid oxidation, mitochondrial function, and systemic inflammation. Exercise-induced myokines exert insulin-sensitizing and anti-inflammatory effects, whereas myostatin and tumor necrosis factor-alpha (TNF-α) promote metabolic impairment. These pathways reveal extensive crosstalk between SM and key metabolic organs-including the liver, pancreas, AT, intestine, heart, and thyroid gland. In metabolic disease, inflammation-driven changes in deiodinase activity and triiodothyronine (T3) availability further link muscle dysfunction with thyroid imbalance. The aim of this narrative review was to elucidate the complex interplay between myokines, adipokines, inflammation, and insulin res

Insulin resistance (IR) is a central driver of cardiometabolic disease and an increasingly recognized modifier of inflammatory and vascular pathology. Beyond impaired glucose homeostasis, IR emerges from chronic, metabolically induced inflammation ("meta-inflammation") and convergent cellular stress programs that propagate across tissues and organ systems, ultimately shaping endothelial dysfunction, atherogenesis, and cardiometabolic complications. Here, we synthesize multilevel links between insulin receptor signaling, intracellular stress modules (oxidative, endoplasmic reticulum, inflammatory, and fibrotic pathways), tissue-level dysfunction, and systemic inflammatory amplification. This work is a conceptual narrative review informed by targeted database searches and citation tracking, with explicit separation of mechanistic/experimental evidence from human observational and interventional data; causal inferences are framed primarily on mechanistic and interventional findings, whereas associative statements are reserved for observational evidence. We propose an integrative framework in which stress-response pathways are context-dependent and become maladaptive when chronically activated under nutrient excess and persistent inflammatory cues, generating self-reinforcing loops between IR and inflammation that accelerate vascular injury. This framework highlights points of convergence that can guide mechanistic prioritization and translational hypothesis testing.

<b>(1) Background:</b> Insulin resistance (IR) is increasingly recognized not only as a key factor in metabolic and cardiovascular disorders but also as an important contributor to cognitive decline. The growing prevalence of obesity, type 2 diabetes mellitus, and cardiovascular disease (CVD), paralleled by rising rates of dementia, highlights the need for an integrative model linking these conditions. The emerging cardio-metabolic-brain axis proposes a unified model explaining how biomarkers of metabolic stress, adipose-tissue-derived mediators, and abnormalities in laboratory parameters interact with vascular injury and neurodegeneration. <b>(2) Methods:</b> A comprehensive literature review was conducted using MEDLINE, SCOPUS, and Web of Science databases, complemented by additional searches in Embase and Cochrane Library. Studies from the past decade were screened using keywords such as "insulin resistance", "cardio-metabolic-brain axis", "cognitive decline", and "cardiovascular disease". Both epidemiological and mechanistic studies were analyzed to summarize current evidence and identify research gaps. <b>(3) Results and Conclusions:</b> Evidence indicates that insulin resistance contributes to endothelial dysfunction, chronic inflammation, and oxidative stress, driving the metabolic abnormalities characteristic of obesity and type 2 diabetes and promoting both atherosclerosis and neurodegeneration. Individuals with elevated IR-regardless of diabetes status-display highe

Type 2 Diabetes Mellitus (T2DM) is a complex metabolic disorder characterized by insulin resistance, chronic low-grade inflammation, and progressive metabolic dysfunction affecting multiple organs. This review explores the molecular and physiological mechanisms underlying T2DM, emphasizing the role of intracellular metabolic signaling pathways, mitochondrial function, and inter-organ communication in the development and progression of metabolic dysregulation. Particular attention is given to key regulatory pathways such as AMP-activated protein kinase (AMPK) and the mechanistic target of rapamycin (mTOR), which play central roles in cellular energy sensing, glucose metabolism, and lipid homeostasis. Dysregulation of these pathways contributes to impaired insulin signaling, mitochondrial dysfunction, oxidative stress, and altered adipogenesis, all of which are critical factors in the pathophysiology of T2DM. In addition, growing evidence highlights the importance of metabolic crosstalk between skeletal muscle, adipose tissue, liver, pancreas, and the gut microbiota through signaling molecules including adipokines, myokines, hepatokines, and gut-derived metabolites. These inter-organ networks influence systemic inflammation, metabolic flexibility, and glucose homeostasis. Lifestyle factors such as physical activity, nutritional patterns, and micronutrient status have also been shown to modulate these molecular pathways, improving mitochondrial function and insulin sensitivity w

Insulin resistance (IR) describes impaired hormone signaling that triggers compensatory homeostatic responses resulting in hyperinsulinemia, increased accumulation of fatty substrates, lipotoxicity, oxidative stress, inflammation, cell death and fibrosis in target tissues. These processes ultimately lead to organ dysfunction and predispose certain individuals to various types of cancer. In this context, we will review the molecular pathogenesis and clinical significance of IR, its role in 'metaflammation', and the damage caused by IR in the pancreas, cardiovascular system, liver, and kidneys. Additionally, we will discuss principles of drug treatment for IR and outline a research agenda in this field.