Impact of sex on insulin secretion in cystic fibrosis.

CONTEXT: Cystic fibrosis-related diabetes is primarily due to a defect in insulin secretion. Women with cystic fibrosis (CF) are at higher risk of developing CF-related diabetes.

OBJECTIVE

The objective of the study was to examine sex differences in insulin and glucose homeostasis. We hypothesized that in CF, women would display lower insulin secretion than men.

DESIGN

This was a study based on an ongoing observational CF cohort with a mean follow-up of 19.9 ± 5.2 months.

SETTING

The study was conducted at the CF clinic of the Centre Hospitalier de l'Université de Montréal (Québec, Canada).

PATIENTS: From 230 adults with CF (123 men, 107 women) of similar age and functional pulmonary status, 104 retested after the follow-up. Age-matched healthy individuals (25 men, 19 women) were included in the study.

INTERVENTIONS: Participants underwent a 2-hour oral glucose tolerance test with 30-minute interval sample measurements.

MAIN OUTCOME MEASURE: Plasma insulin and glucose levels were measured.

RESULTS

Women with CF had higher overall insulin secretion as compared with men with CF (P ≤ .05) but similar to healthy women (P = .606). Men with CF had lower overall insulin secretion than healthy men (P = .020) and higher insulin sensitivity (P = .009) than women with CF. PATIENTS with CF displayed higher overall glucose excursions than healthy patients. Sex-related differences were still observed in the CF cohort after follow-up.

CONCLUSIONS

Surprisingly, in CF, adult women presented higher insulin secretion than adult men at a comparable level with what is observed in healthy individuals. Potential implications of this sex dimorphism in CF remain to be established.