Jennie Brand-Miller has championed the role of the glycaemic index (GI) in health and disease and transformed the way carbohydrate foods are considered by scientists, physicians and consumers. She demonstrated that the adverse effects of high blood sugars apply not only to diabetes but to obesity and cardiovascular disease. By establishing international standards and testing services for industry and compiling reliable databases, Brand-Miller facilitated epidemiological, agricultural and industrial research application of the GI around the world. By writing books and launching a food labelling program, she translated new knowledge into actions that helped millions of individuals to adopt healthier diets.