In adult diabetic rats, a diet containing barley had a modulating effect on the symptoms of diabetes (blood glucose concentration and water consumption) when compared with a starch or sucrose-based diet. It was postulated that the beneficial effect of barley might be explained by its very high content of chromium (5.69 micrograms/g). Supplementation of the sucrose-based diet with an amount of trivalent inorganic chromium calculated to be equivalent to the available chromium in the barley-based diet abolished the differences in response to the diabetic state.