Recent data have suggested a key role for tumor necrosis factor (TNF)-alpha in 
the insulin resistance of obesity and non-insulin-dependent diabetes mellitus 
(NIDDM). TNF-alpha expression is elevated in the adipose tissue of multiple 
experimental models of obesity. Neutralization of TNF-alpha in one of these 
models improves insulin sensitivity by increasing the activity of the insulin 
receptor tyrosine kinase, specifically in muscle and fat tissues. On a cellular 
level, TNF-alpha is a potent inhibitor of the insulin-stimulated tyrosine 
phosphorylations on the beta-chain of the insulin receptor and insulin receptor 
substrate-1, suggesting a defect at or near the tyrosine kinase activity of the 
insulin receptor. Given the clear link between obesity, insulin resistance, and 
diabetes, these results strongly suggest that TNF-alpha may play a crucial role 
in the systemic insulin resistance of NIDDM. This may allow for new treatments 
of disorders involving resistance to insulin.