Assessing Glycaemic Control in Cystic Fibrosis

  • Jennifer Helm

    Student thesis: Doctor of Medicine


    Assessing Glycaemic Control in Cystic FibrosisJennifer Helm, University of Manchester, Doctor of Medicine (MD) thesis submission, June 2011Four studies investigating the assessment of glycaemic control in cystic fibrosis are presented within this thesis.The first was a validation study of continual glucose monitoring (CGM) in cystic fibrosis (CF). 50 stable adults with CF underwent home CGM for 3 days, during which time they attended the CF centre for OGTT. Gold standard fasting (0 hour) plasma glucose and 2 hour plasma glucose values during OGTT were compared with concurrent CGM sensor glucose values using a 'limits of agreement' analysis. CGM was found to be valid in adults with CF, with its accuracy being consistent with that published in non-CF populations.The next investigation compared OGTT with CGM with several objectives: to determine whether OGTT is a relevant and adequate measure of glycaemia in CF, find out whether CGM could offer a superior alternative to OGTT and explore whether OGTT and CGM results are associated with prior change in lung function and weight in adults with CF. Data from the first study was used to show that the OGTT can only identify abnormal glycaemic control in CF at a late stage, and that CGM is a more relevant reflection of everyday glycaemia in CF. No correlation was found between prior change in lung function and nutritional status in CF and glycaemia measured by OGTT or CGM. The subsequent study investigated whether CGM could identify early abnormal glycaemic control in CF. This involved ten non-CF healthy controls undergoing the same study protocol as the 50 stable adults with CF, to determine 'normal' glycaemic control parameters. Of 25 CF patients with normal glucose tolerance by OGTT, 19 (76%) had significantly higher mean and/or variability of CGM levels than healthy controls. This lead to changes in their management, including 2 subjects being commenced on insulin therapy.The final investigation was a questionnaire study, asking the 50 CF patients to provide information on their experience of undergoing CGM. 58% of patients responded, with replies indicating that they found CGM broadly acceptable, interfering little in their lives and that their experiences were generally positive. This insight into patients' experiences of CGM can be used to guide future clinical and research roles for this tool.These studies have provided novel data regarding the assessment of glycaemic in CF. Information captured by CGM has greater relevance to CF patients' daily lives than OGTT. CGM can identify early problems with glycaemic control leading to changes in management that may not be detected by conventional measures. CGM offers potential in further clinical application and research to improve the lives and outcomes for adults with CF.
    Date of Award31 Dec 2011
    Original languageEnglish
    Awarding Institution
    • The University of Manchester
    SupervisorAnthony Kevin Webb (Supervisor) & Andrew Jones (Supervisor)


    • oral glucose tolerance test
    • continual glucose monitoring
    • cystic fibrosis
    • glycaemic control

    Cite this