Free fatty acids and insulin resistance.
OBJECTIVE
Dysregulation of free fatty acid metabolism is a key event responsible for insulin resistance and type 2 diabetes. According to the glucose-fatty acid cycle of Randle, preferential oxidation of free fatty acids over glucose plays a major role in insulin sensitivity and the metabolic disturbances of diabetes mellitus. However, other mechanisms are now described to explain the molecular basis of insulin resistance.


RESULTS
Recent studies have suggested that local accumulation of fat metabolites such as ceramides, diacylglycerol or acyl-CoA, inside skeletal muscle and liver, may activate a serine kinase cascade leading to defects in insulin signalling and glucose transport. Inflammation and oxidative stress are also potent mechanisms which could lead to a state of insulin resistance. Finally, modulation of transcription by free fatty acids through their binding to peroxisome proliferator-activated receptors could also contribute to impaired glucose metabolism.


CONCLUSIONS
The increase in free fatty acid flux resulting from increased lipolysis secondary to adipose-tissue insulin resistance induces or aggravates insulin resistance in liver and muscle through direct or indirect (from triglyceride deposits) generation of metabolites, altering the insulin signalling pathway. Alleviating the excess of free fatty acids is a target for the treatment of insulin resistance.
Delarue
Jacques
J
Laboratoire Régional de Nutrition Humaine and EA-948, CHU de Brest et Université de Bretagne Occidentale, Brest, France. jacques.delarue@univ-brest.fr
Magnan
Christophe
C
D000273:Adipose Tissue / Q000378:metabolism*; D005230:Fatty Acids, Nonesterified / Q000378:metabolism*; D006801:Humans; D007333:Insulin Resistance; D008066:Lipolysis; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism; D047492:Peroxisome Proliferator-Activated Receptors / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D014280:Triglycerides / Q000378:metabolism*
D005230:Fatty Acids, Nonesterified; D047492:Peroxisome Proliferator-Activated Receptors; D014280:Triglycerides; D017346:Protein Serine-Threonine Kinases