Challenges in the dietary treatment of cystic fibrosis related diabetes mellitus

Cystic fibrosis related diabetes mellitus is an increasingly recognized pro blem as survival in patients with cystic fibrosis improves. In a 5 year ret rospective study of 627 children and adults attending Toronto cystic fibros is clinics, we identified 57 (9%) patients with cystic fibrosis related dia betes mellitus; four (1.3%) of 301 children (<18 years) and 53 (16%) of 326 adults. The development of this complication of cystic fibrosis is associa ted with increased mortality, deteriorations in both respiratory and nutrit ional status, and the development of late microvascular, but not macrovascu lar, diabetic complications. Unfortunately, systematic review of the litera ture provides few well designed studies that provide sound evidence for cli nical practice. Recommendations are therefore often based on anecdote, rath er than physiological or outcomes research. Dietary therapy combines the pr inciples of the dietary management of both cystic fibrosis and diabetes mel litus, but emphasizes the need for a high energy diet (> 100% of recommende d daily intake) in patients with cystic fibrosis related diabetes mellitus. The importance of calories from fat is emphasized, with no restriction on total carbohydrate intake. Insulin intake mirrors carbohydrate intake. Rout ine dietary therapy is straightforward, but challenges occur due to both co mplications of cystic fibrosis and advancing disease. If a patient with cys tic fibrosis related diabetes mellitus is malnourished, overnight enteral t ube feeding is often used, with an adjusted insulin regimen. There is a gre at need for both physiological and outcomes research to provide sound scien tific evidence for the dietary treatment of cystic fibrosis related diabete s mellitus. (C) 2000 Harcourt Publishers Ltd.