Rapid-Acting Insulin Used to Treat a Case of Early Cystic Fibrosis–Related Diabetes Complicated by Post Prandial Hypoglycemia

Cystic fibrosis–related diabetes (CFRD) is one of the most common nonrespiratory complications of cystic fibrosis (CF). There is a lack of clinical research to provide guidance on optimal treatment regimens for various subtypes of CFRD. This case describes an 18-year-old woman, diagnosed with CF in infancy, who presented to our clinic for evaluation of possible CFRD and episodes of hypoglycemia. Subsequent testing revealed normal fasting glucose with elevated blood glucose levels on oral glucose tolerance test, consistent with the diagnosis of CFRD without fasting hyperglycemia. She was found to have large glycemic excursions after carbohydrate-containing meals, followed by delayed postprandial hypoglycemia. We initiated low-dose mealtime rapid-acting analog insulin and saw both a decrease in her postprandial hyperglycemia as well as resolution of her hypoglycemic episodes. This case highlights the spectrum of pancreatic dysfunction and insulin dysregulation in CFRD as well as the benefit of prandial insulin alone as a treatment option.