Glucose has been proposed as a mediator of aging processes by means of glycation reactions resulting in advanced glycosylation end-products, thereby altering protein and DNA function. Testing this provocative concept has a high priority in gerontologic research. In this study, food restriction of rats--a procedure which markedly retards aging processes--was used to test the glycation hypothesis. Food-restricted rats were found to have a sustained plasma glucose concentration and percentage glycosylation of hemoglobin significantly lower than those of ad libitum fed rats. These findings are consistent with and provide support for the glycation hypothesis.