Vascular permeability in diabetics and implications for therapy.

Several factors contribute to increased vascular permeability in diabetes mellitus, namely hyperglycaemia leading to increased production of diacylglycerol and thence protein kinase C, non-enzymatic glucosylation generating free radicals and lipid peroxides, sorbitol formation, loss of endothelial cell surface heparan sulphates, and the action of arachidonate derivatives that affect endothelial cell contractility. In view of the importance of oxidative damage, serious consideration must be given to therapeutic regimens that utilise vitamin E or ascorbic acid or D-myoinositol. Probucol is an available antioxidant whose properties have received insufficient attention. The oleate of monounsaturated oil diets is likewise anti-oxidant. Furthermore there is a possibility of replacing lost surface heparan sulphates.