LDL-cholesterol and insulin are independently associated with body mass index in adult cystic fibrosis patients

Abstract

Background The median life expectancy of cystic fibrosis (CF) patients has increased dramatically over the last few years and we now observe a subset of patients with a body mass index (BMI) exceeding 25 kg/m(2). The aim of this study was to characterize these individuals and to identify factors associated with higher BMI. Methods This is a cross sectional study including 187 adult CF subjects. Percent predicted forced expiratory volume in 1s (%FEV(1)), blood lipid profiles as well as fasting glucose and insulin levels were evaluated. Subjects also had an oral glucose tolerance test (OGTT) and the area under the curve (AUC) for glucose and insulin was calculated. CF subjects were then stratified according to the following BMI categories: underweight: BMI≤18.5 kg/m(2); normal weight: 18.5 kg/m(2)<BMI<25 kg/m(2); and overweight or obese: BMI≥25 kg/m(2). Results Overweight subjects were older and less likely to have enzyme supplementation compared to the other two groups. Furthermore, this group exhibits higher levels of fasting insulin, total and LDL-cholesterol as well as insulin AUC. Further analyses demonstrated that BMI correlated with %FEV(1), fasting insulin, insulin AUC, total cholesterol, LDL-cholesterol and the ratio of HDL-cholesterol to total cholesterol and that %FEV(1), insulin AUC and LDL-cholesterol were independent associated with BMI. Discussion Overweight CF subjects have higher fasting insulin and insulin AUC as well as total and LDL-cholesterol. Furthermore, we also demonstrated that LDL-cholesterol, insulin AUC are independently associated with BMI in a population of adult CF subjects.