Am J C/in Niitr 1996:64:643-4. Printed in USA. © 1996 American Society for Clinical Nutrition 643 Protein metabolism in cystic fibrosis”2

The importance of nutritional status to morbidity and mor-tality in cystic fibrosis (CF) has been shown ( 1), and the resultant goal of achieving normal nutrition and growth for CF patients of all ages has been adopted (2). In CF. the problem is usually one of energy balance, in which protein intakes are adequate but energy imbalance occurs as a result of a combi-nation of poor energy intake, increased energy losses, and increased energy needs (3). There is also increasing concern about abnormalities of glucose metabolism in CF. and in a recent prospective study the annual incidence of diabetes in CF patients aged 10-19 y was 5%, with a higher rate of impaired glucose tolerance (4). The occurrence of CF-related diabetes is important, being associated with both undernutrition and in-creased mortality in adults with CF (5). In an earlier study, Kien et al (6) showed children with CF to have impaired insuli