PracticeUpdate: Diabetes

EDITOR’S PICKS 13

Diabetes in Individuals With Cystic Fibrosis: A Review Diabetic Medicine: A Journal of the British Diabetic Association Take-home message • This review describes the unique form of diabetes that occurs in individuals with cystic fibrosis. • The authors describe the pattern of insulin and metabolic abnormalities that develop in individuals with cystic fibrosis as they age, and how these changes can affect lung function and other aspects of the cystic fibrosis disease process. The authors also discuss treatment strategies in this unique patient population.

COMMENT By Melissa S. Putman MD, MSc P atients with cystic fibrosis (CF) are living longer than ever due to significant improvements in available treatments and clinical care over the past several decades. As life expectancy improves, non-pulmonary complications are becoming increas- ingly prevalent and burdensome, including CF-related diabetes (CFRD). This comprehensive review by Bridges et al summarizes the unique challenges faced by this patient population based on a symposium held at the Diabetes UK Professional Conference. CFRD affects up to 20% of adolescents and 35% to 50% of adults with CF, and the development of CFRD is associated with clinical deterioration, including worsening pulmonary function, com- promised nutrition, and increased mortality. Insulin is the treatment of choice for CFRD and has been shown to improve clinical status and decrease mortality. However, diabetes adds to what is already a significant medical burden these patients must carry. New CF treatments, including cystic fibrosis transmembrane receptor (CFTR) mod- ulators, and new technologic advances in diabetes management may have sig- nificant potential for improving glycemic control in patients with CFRD.

Dr. Putman is Assistant Professor in Pediatrics at Harvard Medical School, Attending Physician in Adult and Pediatric

Endocrinology at Boston Children’s Hospital and Massachusetts General Hospital, and Endocrinologist for the MGH and BCH Cystic Fibrosis Centers in Boston, Massachusetts.

Abstract Individuals with cystic fibrosis and pancreatic insufficiency have a gradual decline in insulin secretion over time, which results in an increase in the prevalence of diabetes with age; up to 50% of adults with cystic fibrosis aged over 35 years have diabetes. Cystic fibrosis-related diabetes differs from Type 1 and Type 2 diabetes in sev- eral ways; there is a pattern of insulin deficiency with reduced and delayed insulin response to carbohydrates but a sparing of basal insulin that results in glucose abnormalities, which are frequently characterized by normal fasting glu- cose and postprandial hyperglycaemia. Insulin deficiency and hyperglycaemia, even at levels which do not reach the threshold for a diag- nosis of diabetes, have an adverse impact on

lung function and clinical status in people with cystic fibrosis. Although the risk of microvas- cular complications occurs as in other forms of diabetes, the main reason for treatment is to pre- vent deterioration in lung function and weight loss; treatment may therefore be required at an earlier stage than for other types of diabetes. Treatment is usually with insulin, but manage- ment needs to take into account all the other medical issues that arise in cystic fibrosis. Unique Challenges of Cystic Fibrosis-Related Diabetes. Diabet Med 2018 Apr 23;[EPub Ahead of Print], N Bridges, R Rowe, RIG Holt. www.practiceupdate.com/c/68232

" New CF treatments, including cystic fibrosis transmembrane receptor (CFTR) modulators, and new technologic advances in diabetes management may have significant potential for improving glycemic control in patients with CFRD. "

VOL. 2 • NO. 3 • 2018