These secretory defects were found to be frequent, also in normotolerant CF patients who compensate with an increased insulin sensitivity (9, 10, 11, 12, 13) and to worsen with advancing age, as we found in the population followed at the CF Center in Milan (14), in which nomograms for OGTT-derived insulin secretory parameters were produced to explore their clinical associations and significance in prospective studies. The gene discussed is INS; the disease is cystic fibrosis.