title: Insulin secretion, nutritional status and respiratory function in cystic fibrosis patients with normal glucose tolerance.
abstract: OBJECTIVE
  Impaired growth and nutritional status in CF may be related to progressive insulin deficiency before CF-Related Diabetes has established. Aim of this study was to analyse the association of circulating insulin with nutritional status and lung function in CF patients with normal glucose tolerance (NGT).
  
  
  METHODS
  We performed OGTT in 152 consecutive CF patients aged 8-20 years: 115 of them had NGT and were included in the study. Areas under the curves (AUC) of glucose, insulin and c-peptide after 120 min were calculated. Quartiles (Q) of increasing fasting insulin (fINS-Q) and c-peptide (fCP-Q) levels were calculated in CF patients. Respiratory function parameters (FEV1, FVC), Standard Deviation Scores (SDS) of height, weight and BMI were compared between Q1 and the three higher Q. Multiple regression analysis was used to analyse the association of fasting insulin, c-peptide or OGTT derived indices with nutritional or respiratory parameters.
  
  
  RESULTS
  Compared to patients in fINS-Q4 or fCP-Q4, those in fINS-Q1 or in fCP-Q1 respectively showed lower levels of insulin AUC or c-peptide AUC (both P < 0.0001), weight-SDS (P = 0.013, P = 0.007), BMI-SDS (P = 0.010, P = 0.002), FEV1 (P = 0.076, P = 0.013) and FVC (P = 0.101, P = 0.009). Age- and gender-adjusted regression analysis showed significant associations of fINS and fCP with SDS of BMI (P = 0.023 and P = 0.001 respectively), fCP was significant associated with FEV1 (P = 0.01). AUC insulin/AUC glucose ratio (P < 0.0001) and AUC c-peptide/AUC glucose ratio (P = 0.0001) were significantly associated with FEV1.
  
  
  CONCLUSIONS
  Insulin deficiency in CF patients with NGT has a significant impact on clinical outcomes.
authors.affiliation: Department of Paediatrics, Cystic Fibrosis Center of Milan, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Via Commenda 9, 20122 Milan, Italy. gianfranco.alicandro@policlinico.mi.it
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Alicandro
authors.forename: Pier Maria
authors.initials: PM
authors.lastname: Battezzati
authors.forename: Alberto
authors.initials: A
authors.lastname: Battezzati
authors.forename: Chiara
authors.initials: C
authors.lastname: Speziali
authors.forename: Laura
authors.initials: L
authors.lastname: Claut
authors.forename: Valentina
authors.initials: V
authors.lastname: Motta
authors.forename: Silvana
authors.initials: S
authors.lastname: Loi
authors.forename: Carla
authors.initials: C
authors.lastname: Colombo
mesh_terms: D000293:Adolescent; D019540:Area Under Curve; D001786:Blood Glucose / Q000032:analysis; D002096:C-Peptide / Q000097:blood; D002648:Child; D003550:Cystic Fibrosis / Q000503:physiopathology*; D005215:Fasting; D005260:Female; D018149:Glucose Intolerance / Q000378:metabolism*; D005951:Glucose Tolerance Test / Q000379:methods; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D016014:Linear Models; D008297:Male; D009752:Nutritional Status; D012119:Respiration; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D002096:C-Peptide; D007328:Insulin