Factors affecting diabetes mellitus onset in cystic fibrosis: Evidence from a 10-year follow-up study

This study reports the results of genotype characterization and of a 10-y p rospective evaluation of clinical status, glucose tolerance and insulin sec retion in 28 originally normoglycaemic patients with cystic fibrosis (CF). The aim of the study was to assess whether any genetic, clinical or metabol ic parameters could identify in advance those patients at risk of developin g diabetes mellitus over time. During the follow-up 42.8% of patients becam e diabetic. Neither gender, age nor clinical parameters were significantly different at entry in the patients who eventually developed diabetes compar ed with those who did not. Insulin secretion during oral glucose tolerance tests (OGTT) deteriorated over time in both groups, whereas a progressive d eterioration of glucose tolerance was only evident in the patients who deve loped diabetes and increased baseline glucose areas were the only predictiv e parameter of diabetes onset. Genotype analysis revealed significant diffe rences between patients with and without diabetes: Delta F508 homozygosis w as more frequent in the first group and N1303K mutation in the second group . In conclusion, in CF: (i) increased glucose areas during OGTT and deterio ration of glucose tolerance over time can predict the evolution towards dia betes; and (ii) Delta F508 homozygosis may predispose to the risk of diabet es, whilst N1303K mutation seems to play a protective role.