From:  Disruption of the transsulfuration pathway as a sulfur-driven etiology of insulin resistance: proinsulin misfolding, disulfide bond deformation, and PDI dysregulation

 This comparative framework highlights the novel perspective of the Sulfur-Dependent Misfolding Hypothesis in redefining T2DM as a sulfur metabolism disorder, contrasting it with traditional paradigms.

Comparative dimensionTraditional paradigm of T2DMSulfur-Dependent Misfolding Hypothesis
Root causePeripheral insulin resistance is driven by obesity, lipotoxicity, and inflammation.Structural misfolding of insulin due to disulfide bond disruption caused by organic sulfur deficiency.
Initiation siteSkeletal muscle, liver, and adipose tissue.Mitochondrial dysfunction in intestinal epithelial cells impairs sulfur metabolism.
Pathophysiological focusPost-receptor signaling defects (IRS, PI3K, Akt).Primary insulin deformation with reduced receptor affinity due to disrupted disulfide bonds.
Explanation of the hyperinsulinemia + hyperglycemia paradoxCompensatory hypersecretion due to peripheral resistance.Endogenous insulin is misfolded and non-functional; exogenous insulin remains effective due to its intact structure.
Immunological mechanismChronic inflammation in adipose tissue and macrophage activation.Glutathione depletion induces NF-κB and JNK pathways via oxidative stress and endotoxemia.
Role of the gutSecondary influence via microbiome and inflammation.Primary site of dysfunction initiating mitochondrial suffocation, impaired sulfur metabolism, and mucosal barrier breakdown.
Insulin signaling defectImpaired receptor signaling due to inflammation and phosphorylation of IRS.Insulin fails to initiate signaling due to misfolded structure with up to 70% loss in receptor affinity.
Therapeutic strategyBlood glucose control via metformin, GLP-1 agonists, or exogenous insulin.Sulfur restoration through NAC, MSM, and dietary methionine/cysteine to stabilize insulin structure.
Experimental accessibilityHOMA-IR index and indirect measures of resistance.Direct structural assessment of insulin via LC-MS/MS and Raman spectroscopy.
Biochemical depthFocuses downstream of the IR.Traces the issue upstream to insulin biosynthesis and protein folding integrity.
Innovation potentialIncremental improvements to a saturated model.A paradigm shift introducing sulfur metabolism as a central therapeutic and diagnostic axis.
Philosophical reframingThe body becomes resistant to insulin.The body produces dysfunctional insulin; the issue lies at the source.

Akt: protein kinase B; IR: insulin receptor; IRS: IR substrate; JNK: c-Jun N-terminal kinase; LC-MS/MS: liquid chromatography-tandem mass spectrometry; MSM: methylsulfonylmethane; NAC: N-acetylcysteine; NF-κB: nuclear factor kappa-light-chain-enhancer of activated B cells; PI3K: phosphoinositide 3-kinase; T2DM: type 2 diabetes mellitus; HOMA-IR: homeostatic model assessment of insulin resistance.