Continuous glucose monitoring to evaluate glycaemic abnormalities in cystic fibrosis

Abstract

ObjectiveThis study aimed to determine the glycaemic profile of patients with cystic fibrosis using a continuous glucose monitoring system (CGMS), and to evaluate the associations of glycaemic abnormalities with sex, age, pubertal stage, CFTR gene mutations, nutritional status, lung function, oral glucose tolerance test, glycated haemoglobin concentrations, fasting insulin concentrations, C peptide concentrations and exocrine pancreatic function.Study designThis observational study evaluated CGMS data from 39 patients with cystic fibrosis who were treated at a referral centre. The patients were 10–19.9 years old, and were categorised according to whether they had normal results (27 patients) or glucose intolerance (12 patients) during the oral glucose tolerance test.ResultsThe maximum interstitial glucose concentration among individuals with normal oral glucose tolerance test results was 174.9±65.1 mg/dL (9.7–3.61 mmol/L), compared with 170.4±40.9 mg/dL (9.46–2.27 mmol/L) among individuals with glucose intolerance. The CGMS revealed that 18 of the 27 patients with normal oral glucose tolerance test results had peak interstitial glucose concentrations of >140 mg/dL (7.8 mmol/L), and that 4 of these individuals had peak levels of >200 mg/dL (11.1 mmol/L). None of the analysed clinical or laboratory characteristics predicted the occurrence of hyperglycaemic peaks on CGMS.ConclusionsThe present study revealed that CGMS could detect hyperglycaemia among patients with cystic fibrosis and ‘normal’ oral glucose tolerance test results, and that their clinical and laboratory characteristics were not useful in discerning between patients who did and did not exhibit these excursions.

Continuous glucose monitoring guided insulin therapy is associated with improved clinical outcomes in cystic fibrosis-related diabetes

“…The variation in study sizes and thresholds utilised for classification of dysglycaemia may partly explain the differing prevalence of CFRD seen across these studies. Although further criticism of our study could be that the dysglycaemia seen on CGM in our cohort might have been detected by OGTT, CGM is well validated in detecting abnormalities not apparent on OGTT, [19,37,38] and the mean Hba1c in the insulin treated group was b40 mmol/ mol, a cut-off below which only 6% have a positive OGTT. [39] In conclusion, we have demonstrated for the first time that insulin treatment based on CGM abnormalities alone can be associated with improved pulmonary function and weight in the short-term with reduced pulmonary function decline in the longer-term.…”

Comparison of continuous glucose monitoring to reference standard oral glucose tolerance test for the detection of dysglycemia in cystic Fibrosis: A systematic review

“… Moreau [71] 2008 France Prospective Consecutive 32 26 Medtronic 3 days Normal defined as SG < 7.8 mmol/L. SG > 11.1 mmol/L defined as CFRD O’Riordan [72] 2006 Ireland Prospective Unclear 8 Pediatric NS Medtronic 2 days SG peak > 11.1 mmol/L defined as CFRD Pu [58] 2018 Brazil Prospective Consecutive 39 15 Medtronic Minimed 1–2 days >1 SG peak > 7.8 mmol/L defined as impaired. > 1 SG peak > 11.1 mmol/L defined CFRD Schiaffini [64] 2010 Italy Prospective Consecutive 17 13 Medtronic Minimed 3 days >2 SG peaks > 11.1 mmol/L defined as CFRD Taylor-Cousar [63] 2016 USA Prospective Consecutive 18 32 Medtronic 3 days > 2 separate days of > 7.8 mmol/L defined as impaired or > 11.1 mmol/L defined CFRD Widger [73] 2011 Australia Prospective Consecutive 4 14 Not specified 3 days >1 SG peak > 11.1 mmol/L defined as CFRD *Studies with high risk of selection bias due to inclusion of individuals with cystic fibrosis with reportedly previously abnormal blood glucose levels NS not specified, SG sensor glucose result on continuous glucose monitoring, AUC area under the curve …”

“…A total of 15 studies were included in a qualitative analysis (See Table 3 ) with Dobson et al [48] evaluating correlations between CGM and both fingerpick and plasma blood glucose levels. CGM was compared to HbA1c (n = 11) [47] , [49] , [50] , [51] , [52] , [53] , [54] , [55] , [56] , [57] , [58] fingerpick blood glucose levels (n = 3) [48] , [59] , [60] and plasma blood glucose level (n = 2) [48] , [61] . Two studies [47] , [50] also performed OGTT alongside CGM and HbA1c.…”

Intermittent Use of Continuous Glucose Monitoring: Expanding the Clinical Value of CGM

“…For example, clinical symptoms of diabetes, which is present in 20%-50% of youths/adults with CF, typically progress slowly and sometimes insidious, and glucose abnormalities cannot be detected sufficiently with diagnostic measures like an oral glucose tolerance test. 88-92 It has also been shown in youth that high glycemic excursions correlate with a decline of lung function. 93 CGM-guided insulin therapy is associated with improved clinical outcomes as weight gain and pulmonary parameters.…”