Early assessment of glucose abnormalities during continuous glucose monitoring associated with lung function impairment in cystic fibrosis patients

Abstract

Background: Cystic fibrosis-related diabetes (CFRD) is correlated with a decline in lung function. Under certain circumstances, oral glucose tolerance test (OGTT) screening, used to diagnose CFRD, fails to reveal early glucose tolerance abnormalities. In this situation, continuous glucose monitoring (CGM) could be a useful tool for evaluating early abnormalities of glucose tolerance in CF patients. We aimed to study the CGM glucose profile in CF patients with normal OGTT screening results and to evaluate lung function and nutritional status according to the CGM glucose profile.

Methods: We assessed glycemic control, the CGM glucose profile, nutritional status, lung function antibiotic courses and colonization (P. aeruginosa and S. aureus) in CF patients, aged 10 years and over, with normal screening OGTT results (blood glucose at T120 min < 7.8 mmol/l). Two groups were identified according to the max CGM glucose value: Group 1<11 mmol/l and Group 2 ≥ 11 mmol/l.

Results: Among the 38 patients with normal OGTT, 12 (31.6%) were in Group 2. Compared to Group 1, Group 2 patients exhibited a significant impairment in lung function: FEV1, 68.2 ± 25.6% vs. 87.3 ± 17%, p = 0.01 and FVC, 86.1% ± 19.4% vs. 99.3% ± 13.4%, p=0.021, as well as a higher rate of colonization by P. aeruginosa: 83.3% vs. 44%, p=0.024. Nevertheless, there were no differences in nutritional status (BMI standard deviation score: p = 0.079; prealbumin: p = 0.364).

Conclusions: CGM reveals early abnormalities of glucose tolerance that remain undiagnosed by OGTT screening and are associated with worse lung function and a higher prevalence of P. aeruginosa colonization in patients with CF.

Clinical trial registration number: NCT00476281.

Keywords: CGM; Cystic fibrosis; Early glucose tolerance abnormalities; Lung function; OGTT.