Glucose Intolerance in Cystic Fibrosis

Abstract Moderate to severe oral glucose intolerance was observed in 42 per cent of 31 patients with cystic fibrosis of the pancreas. Serum insulin concentrations after glucose were low in all patients regardless of glucose tolerance. When glucagon or tolbutamide was infused at the height of the reduced insulin response to oral glucose, serum insulin levels promptly increased 100 per cent or more in all cases. Since family histories, characteristic complications and post-mortem signs of diabetes mellitus were absent and the decrease in the number of beta cells was only modest, the glucose intolerance in cystic fibrosis is probably not due to coexistent diabetes mellitus or to beta-cell loss but, rather, to the anatomic disorganization of the islands of Langerhans produced by fibrosis of the pancreas.