METABOLIC AND CLINICAL EVENTS PRECEDING DIABETES-MELLITUS ONSET IN CYSTIC-FIBROSIS

Serial assessments of glucose tolerance, of glucose and insulin areas during an oral glucose tolerance test (OGTT) and of clinical parameter s as well were evaluated retrospectively in seven diabetic cystic fibr osis patients (study group) during the 4-6.3 years that preceded diabe tes mellitus diagnosis. The same metabolic and clinical parameters wer e also evaluated in seven age-matched patients who did not develop dia betes during a similar observation period (control group). In the stud y group, glucose tolerance was impaired in all patients but one since the first OGTT and glucose areas progressively increased over time, wh ereas in the control group glucose tolerance remained stable during th e whole observation period. A significant and progressive blunting of insulin secretion occurred over time in both groups, Insulin secretion , however, was reduced but not exhausted at diabetes diagnosis. Neithe r modification of glycosylated haemoglobin levels over time nor serum islet cell antibodies at diabetes onset were observed in the study gro up, The overall clinical course of the disease was not different in ei ther group and remained stable during the observation period. These re sults indicate that in cystic fibrosis diabetes mellitus onset is prec eded by a long-standing deterioration of glucose tolerance, whilst ins ulin secretion progressively declines over time, irrespectively of glu cose tolerance status, The prediabetic worsening of glucose tolerance is not necessarily linked to a worsening of overall clinical status.