Insulin resistance is loss of signal fidelity across tissues

Course overview

A comprehensive molecular and physiological exploration of insulin receptor kinetics, post-receptor signaling nodes, ectopic lipid accumulation, and metabolic inflexibility.

Track

Metabolic systems

Level

Core course

Lessons

14

Estimated duration

70 min

Scientific review panel

Endocrine Physiology

Models pancreatic beta-cell insulin secretion, pulsatility, and hepatic clearance.

Molecular Signaling

Maps IR tyrosine kinase activation, IRS-1/2 phosphorylation, PI3K/Akt pathway, and GLUT4 translocation.

Lipid Metrology

Quantifies diacylglycerol (DAG), ceramide accumulation, and novel PKC activation.

Translational Research

Frames GLP-1, GIP, dual/triple incretin agonists, and 5-Amino-1MQ in research contexts.

Complete course curriculum (14 lessons)

1. Lesson 1

   Metabolic Architecture & Glucose Homeostasis

   Learning objective:

   Understand systemic glucose flux, basal turnover, and organ-specific utilization.

   Core mechanism:

   Euglycemia is maintained by a dynamic equilibrium between hepatic glucose production and peripheral uptake by skeletal muscle, adipose, and brain.

   Key takeaway:

   Skeletal muscle accounts for over 70% of postprandial insulin-mediated glucose disposal.

2. Lesson 2

   The Insulin Receptor & Canonical Signaling Cascade

   Learning objective:

   Sequence the intracellular phosphorylation relay from receptor binding to GLUT4 vesicle exocytosis.

   Core mechanism:

   Insulin binding induces receptor beta-subunit autophosphorylation, recruiting IRS-1/2 to activate Class IA PI3-kinase, generating PIP3 to recruit and activate Akt2 via PDK1 and mTORC2.

   Key takeaway:

   Akt2 activation is the indispensable master node for metabolic insulin action.

3. Lesson 3

   Target Tissues: Muscle, Liver & Adipose Dynamics

   Learning objective:

   Contrast insulin action across primary metabolic tissues.

   Core mechanism:

   In muscle, insulin drives glucose uptake. In liver, it suppresses gluconeogenesis and activates lipogenesis. In adipose, it suppresses lipolysis via HSL inhibition.

   Key takeaway:

   Insulin resistance is tissue-specific and can exhibit selective pathway impairment.

4. Lesson 4

   Ectopic Lipid Deposition & DAG-PKC Mechanism

   Learning objective:

   Trace lipid-induced insulin resistance at the molecular level.

   Core mechanism:

   Intracellular diacylglycerol (DAG) accumulation recruits and activates novel PKC isoforms (PKC-theta in muscle, PKC-epsilon in liver), which phosphorylate IRS-1/2 on inhibitory serine residues.

   Key takeaway:

   Ectopic intracellular lipid intermediates directly uncouple insulin receptor kinase from downstream Akt activation.

5. Lesson 5

   Mitochondrial Dysfunction & Incomplete Beta-Oxidation

   Learning objective:

   Examine the role of fatty acyl overload and mitochondrial acylcarnitine accumulation.

   Core mechanism:

   Overloading mitochondrial oxidative capacity leads to accumulation of incompletely oxidized lipid species, generating oxidative stress and impairing glucose metabolism.

   Key takeaway:

   Metabolic inflexibility reflects the inability to seamlessly switch between carbohydrate and lipid oxidation.

6. Lesson 6

   Adipose Tissue Remodeling & Chronic Low-Grade Inflammation

   Learning objective:

   Analyze how adipocyte hypertrophy drives macrophage infiltration and crown-like structure formation.

   Core mechanism:

   Hypoxic, hypertrophic adipocytes secrete MCP-1, recruiting pro-inflammatory M1 macrophages that secrete TNF-alpha and IL-6 to phosphorylate IRS-1 on Ser307.

   Key takeaway:

   Inflamed visceral adipose tissue acts as an endocrine driver of systemic insulin resistance.

7. Lesson 7

   Endoplasmic Reticulum (ER) Stress & The UPR

   Learning objective:

   Understand how metabolic overload induces ER stress and activates JNK.

   Core mechanism:

   Excess nutrient flux stresses the ER protein folding machinery, activating PERK, IRE1alpha, and ATF6. IRE1alpha recruits TRAF2 to activate JNK, an inhibitory serine kinase for IRS-1.

   Key takeaway:

   ER stress directly intersects with inflammatory signaling to suppress insulin transduction.

8. Lesson 8

   Hepatic Selective Insulin Resistance & De Novo Lipogenesis

   Learning objective:

   Explain the paradox of failed gluconeogenesis suppression with active lipogenesis in steatotic liver.

   Core mechanism:

   FoxO1 phosphorylation fails (allowing gluconeogenesis to persist), while SREBP-1c activation remains intact, driving de novo lipogenesis and hypertriglyceridemia.

   Key takeaway:

   Selective hepatic insulin resistance exacerbates both fasting hyperglycemia and dyslipidemia.

9. Lesson 9

   Endothelial Dysfunction & Microvascular Recruitment

   Learning objective:

   Examine insulin-mediated nitric oxide (NO) production in the vascular endothelium.

   Core mechanism:

   Insulin normally stimulates eNOS via Akt phosphorylation to dilate terminal arterioles and expand capillary surface area for nutrient exchange; resistance impairs NO synthesis while leaving ET-1 vasoconstriction intact.

   Key takeaway:

   Microvascular insulin resistance reduces nutritive delivery of insulin and glucose to skeletal muscle beds.

10. Lesson 10

    Compensatory Hyperinsulinemia & Beta-Cell Dynamics

    Learning objective:

    Follow the progression from compensated hyperinsulinemia to beta-cell exhaustion.

    Core mechanism:

    Pancreatic beta-cells increase insulin secretion to maintain normal glucose levels. Over time, glucolipotoxicity, amyloid deposition (IAPP), and oxidative stress lead to beta-cell decompensation.

    Key takeaway:

    Hyperinsulinemia is an early compensatory response that eventually degrades beta-cell functional mass.

11. Lesson 11

    Diagnostic Metrology: Clamps, HOMA-IR & Advanced Biomarkers

    Learning objective:

    Compare the gold-standard euglycemic-hyperinsulinemic clamp with surrogate indices.

    Core mechanism:

    The hyperinsulinemic-euglycemic clamp is the gold standard for measuring whole-body insulin sensitivity. HOMA-IR and QUICKI provide validated steady-state surrogates.

    Key takeaway:

    Fasting insulin and HOMA-IR identify metabolic resistance long before fasting glucose rises.

12. Lesson 12

    Muscle Contraction & AMPK-Mediated GLUT4 Translocation

    Learning objective:

    Analyze the insulin-independent pathway of glucose uptake during muscle contraction.

    Core mechanism:

    Muscle contraction activates 5'-AMP-activated protein kinase (AMPK) and calcium/calmodulin-dependent kinase (CaMK), inducing GLUT4 translocation independently of the insulin-IRS-Akt axis.

    Key takeaway:

    Contraction-mediated glucose disposal bypasses defective insulin signaling machinery.

13. Lesson 13

    Incretin Receptor Agonism & Multi-Agonist Pharmacology

    Learning objective:

    Review GLP-1, GIP, and Glucagon receptor signaling in research models.

    Core mechanism:

    GLP-1R and GIPR agonists stimulate glucose-dependent insulin secretion, slow gastric emptying, and centrally suppress appetite. Dual and triple agonists (e.g. Tirzepatide, Retatrutide) activate synergistic metabolic pathways in laboratory studies.

    Key takeaway:

    Multi-receptor incretin agonism represents a major pharmacological paradigm in metabolic research.

14. Lesson 14

    Small Molecules: NNMT Inhibition & 5-Amino-1MQ

    Learning objective:

    Examine Nicotinamide N-methyltransferase (NNMT) biology in adipocyte metabolism.

    Core mechanism:

    NNMT methylates nicotinamide using SAM, depleting methyl donors and NAD+. Preclinical NNMT inhibitors like 5-Amino-1MQ increase intracellular NAD+ and SAM levels in research models.

    Key takeaway:

    Modulating cellular methyl and NAD+ pools represents an active exploratory frontier in adipocyte bioenergetics.