Abstract

Mitochondria govern cellular energy, redox balance, and metabolite signaling across metabolic tissues. In 
obesity, chronic nutrient oversupply glucose, fatty acids, and branched-chain amino acids forces mitochondria 
to operate outside their adaptive ranges, triggering bioenergetic inefficiency, oxidative stress, and maladaptive 
signaling that promote insulin resistance (IR) and accelerate type 2 diabetes (T2D). Key defects include substrate 
overload with incomplete fatty-acid oxidation, electron transport chain (ETC) imbalance, altered TCA cycle 
anaplerosis/cataplerosis, and dysregulated mitochondrial dynamics (excess fission, impaired fusion), biogenesis 
(PGC-1α axis suppression), and selective autophagy (mitophagy). Inter-organelle communication deteriorates: 
mitochondria-associated ER membranes (MAMs) mis-handle Ca2+ and lipid trafficking, linking ER stress to 
impaired insulin action and β-cell failure. Reactive oxygen species (ROS) and lipid peroxides, when sustained, 
inhibit insulin signaling nodes (IRS–PI3K–Akt), reprogram immune cells, and propagate “metaflammation.” 
Tissue context matters: adipose, liver, skeletal muscle, and pancreatic islets exhibit distinct mitochondrial 
vulnerabilities that converge on systemic dysglycemia. Therapeutically, exercise and caloric deficit restore 
mitochondrial quality control, while approved agents (metformin, SGLT2 inhibitors, incretin-based therapies, 
TZDs) exert multi-organ benefits that include improved mitochondrial efficiency or reduced substrate stress. 
Emerging strategies—NAD+ repletion, sirtuin/AMPK activation, redox modulators, mitophagy inducers, and 
safe thermogenic augmentation aim to correct root mitochondrial defects. Precision phenotyping with imaging 
and multi-omics may identify mitochondrial endotypes that guide therapy choices. This review synthesizes 
mechanistic links between mitochondrial dysfunction and progression from obesity-associated IR to T2D and 
outlines therapeutic opportunities to restore organelle health alongside glycemic control.