PANCREATIC ALPHA AND BETA CELL FUNCTION IN CHILDREN WITH CYSTIC FIBROSIS (CF)

Inappropriate plasma glucagon responses to oral glucose have been reported in diabetes (DM), and it has been suggested that alpha cell dysfunction is a characteristic of genetic DM. To further evaluate this hypothesis, plasma glucagon and insulin were measured in children with CF following standard oral glucose (GTT) or intravenous arginine (ATT) tolerance tests. CF patients were classified as being normal (Group A) or variably abnormal (Group B) on the basis of the glucose responses to the GTT. During the GTT plasma glucagon declined by a mean of 64 ± 22 pg/ml in A (p < 0.05) and by 34 ± 7 pg/ml in B (p < 0.01), (A vs. B ns.) while plasma insulins peaked at a mean of 28 ± 5 μU/ml in A and 48 ± 15 μU/ml in B. The ATT resulted in a significantly greater glucagon response at 30 min. in A than B, 622 ± 39 pg/ml vs. 238 ± 74 pg/ml (p < 0.005); while the peak insulin responses were low in both groups, 13 ± 2.6 vs. 21 ± 2.2 μU/ml. These data suggest (1) suppressibility of glucagon to glucose persists despite carbohydrate intolerance in CF patients in contrast to reported non-suppressibility in genetic DM. (2) Insulin responsiveness is obtunded in CF patients in both groups. (3) CF affects pancreatic alpha and beta cell function as well as exocrine function.