To the Editor: In the paper of Handwerger et al., published in the August 28, 1969, issue of the Journal, the interesting observation was reported that in patients suffering from cystic fibrosis of the pancreas, less insulin than normal was needed to dispose of a glucose load in certain cases "with intact glucose tolerance." The authors conclude from these findings that diabetes mellitus as such cannot be incriminated as a cause of the glucose intolerance in cystic fibrosis, and that, perhaps, the beta-cell response to glucose is impaired despite the lack of visible morphologic alterations of the islets.We suggest . . .