FROM:
Diabetes Care 1996 (Mar); 19(3): 257–267
Giugliano D, Ceriello A, Paolisso G
Department of Geriatrics and Metabolic Diseases,
Second University of Naples, Italy
Long–term vascular complications still represent the main cause
of morbidity and mortality in diabetic patients. Although
prospective randomized long–term clinical studies comparing the
effects of conventional and intensive therapy have demonstrated a
clear link between diabetic hyperglycemia and the development of
secondary complications of diabetes, they have not defined the
mechanism through which excess glucose results in tissue damage.
Evidence has accumulated indicating that the generation of
reactive oxygen species (oxidative stress) may play an important
role in the etiology of diabetic complications. This hypothesis
is supported by evidence that many biochemical pathways strictly
associated with hyperglycemia (glucose autoxidation, polyol
pathway, prostanoid synthesis, protein glycation) can increase
the production of free radicals. Furthermore, exposure of
endothelial cells to high glucose leads to augmented production
of superoxide anion, which may quench nitric oxide, a potent
endothelium–derived vasodilator that participates in the general
homeostasis of the vasculature. In further support of the
consequential injurious role of oxidative stress, many of the
adverse effects of high glucose on endothelial functions, such as
reduced endothelial–dependent relaxation and delayed cell
replication, are reversed by antioxidants. A rational extension
of this proposed role for oxidative stress is the suggestion that
the different susceptibility of diabetic patients to
microvascular and macrovascular complications may be a function
of the endogenous antioxidant status.