Cystic fibrosis-related diabetes

Abstract

Cystic fibrosis-related diabetes (CFRD) is the most common metabolic comorbidity of cystic fibrosis (CF) and represents a distinct clinical entity from type 1 and type 2 diabetes mellitus. In individuals with CF and exocrine pancreatic insufficiency, there is a progressive decline in insulin secretion that promotes the development of impaired glucose tolerance and, subsequently, CFRD. Although CFRD is uncommon in children younger than 10 years, up to one-third of this population exhibits abnormalities in glucose tolerance. It is estimated that approximately 50% of individuals with CF will develop CFRD by 30 years of age.

From a pathophysiological perspective, insulin secretion in response to an oral glucose load or a meal is delayed and insufficient, whereas basal insulin secretion is generally relatively preserved. Furthermore, glycemic abnormalities that do not meet the conventional diagnostic criteria for diabetes have already been associated with deterioration in nutritional status, reduced pulmonary function, and poorer clinical outcomes.

Current guidelines advise annual screening for CFRD in all individuals with CF aged over 10 years using the oral glucose tolerance test (OGTT). Continuous glucose monitoring (CGM) has emerged as a promising tool for the early detection of glycemic abnormalities, whereas glycated hemoglobin (HbA1c) demonstrates poor sensitivity.

The treatment of CF-related diabetes aims to optimize glycemic control, preserve nutritional status, and maintain lung function. For this reason, early initiation of insulin therapy is beneficial even in prediabetic stages or before reaching conventional diagnostic criteria. Early intervention is key to halting clinical deterioration and improving the prognosis and quality of life for these patients.