It has been suggested that age effects the glycaemic index value of foods, although there is no data to support this. We therefore studied the blood glucose responses of bread and lentils in seven children (aged 7-17 years) and 10 adults (aged 27-74 years) with insulin dependent diabetes (IDDM). Although there were small differences in the shape of the blood glucose response curves in adults and children, the mean glycaemic index value for lentils was virtually identical in the two groups being 43 +/- 7 in the children and 44 +/- 10 in the adults. We conclude that, in IDDM, the glycaemic index is not affected by age.