Curcumin (diferuloylmethane) is the most active component of turmeric. It is believed that curcumin is a potent antioxidant and anti-inflammatory agent. Experimental studies with diabetic animals demonstrate that curcumin supplementation can suppress cataract development and collagen cross-linking, promote wound healing, and lower blood lipids and glucose levels. The mechanism by which curcumin may cause diabetes-associated vascular damage to regress is not known. Erythrocytes were treated with high levels of glucose (mimicking diabetes) in the presence or absence of curcumin (0-10 muM) in the medium at 37 degrees C for 24 h. This study demonstrates that curcumin prevents protein glycosylation and lipid peroxidation caused by high glucose levels using an erythrocyte cell model. This study also suggests that curcumin may inhibit oxygen radical production caused by high glucose concentrations in a cell-free system, and increase glucose utilization in erythrocytes. This provides evidence for a novel mechanism by which curcumin supplementation may prevent the cellular dysfunction associated with diabetes.