Role of lipids in chemical modification of proteins and development of complications in diabetes

Hyperglycaemia is the major risk factor for the development of complications in both Type I and Type II diabetes; however, there is growing evidence from several clinical trials that dyslipidaemia, including hypertriglyceridaemia, is a significant and independent risk factor for diabetic complications. In this paper, we propose that chemical modification of proteins by lipids may be a underlying pathogenic mechanism linking dyslipidaemia to diabetic complications. Thus the major AGEs (advanced glycation end-products) in tissues, such as carboxymethyl-lysine, carboxyethyl-lysine and hydroimidazolones, may, in fact, be ALEs (advanced lipoxidation end-products), derived from lipids. Increased lipid peroxidation and accelerated ALE formation, possibly catalysed by hyperglycaemia and oxidative stress, may be the mechanistic link between dyslipidaemia and diabetic complications. If correct, this proposal would suggest that inhibition or reversal of glycation, which is a central theme of this symposium, may not be sufficient for protection against diabetic complications.