Continuous glucose monitoring in cystic fibrosis - A practical guide

Early onset of abnormal glucose tolerance in patients with cystic fibrosis: A systematic review and meta-analysis

BACKGROUND

Despite translational evidences suggesting that cystic fibrosis-related abnormal glucose tolerance (CF-related AGT) may begin early in life and is known to be associated with increased morbidity and mortality, current guidelines recommend screening for AGT only from 10 years of age, thus missing the opportunity for early detection and intervention.

METHODS

A systematic review and meta-analysis (PROSPERO number: CRD42021282516) was conducted on studies that reported data on the prevalence of AGT or its subtypes in CF populations. Pooled proportions, risk, and odds ratios with 95 % confidence intervals (CI) were calculated. One-stage dose-response random-effect meta-analysis was used to assess the effect of age on CF-related diabetes (CFRD).

RESULTS

The quantitative analysis included 457 studies and data from 520,544 patients. Every third child with CF (chwCF) (0.31 [95 % CI 0.25-0.37]) and every second adult with CF (awCF) (0.51 [95 % CI 0.45-0.57]) were affected by AGT. Even in the 5-10 years of age subgroup, the proportion of AGT was 0.42 [95 % CI 0.34-0.51]. The prevalence of prediabetes remained unchanged (impaired glucose tolerance in chwCF:0.14 [95 % CI 0.10-0.18]) vs. awCF:0.19 [95 % CI 0.14-0.25]), whereas the proportion of CFRD increased with age (0-5: 0.005 [95 % CI 0.0001-0.15]; 5-10: 0.05 [95 % CI 0.01-0.27]; 10-18: 0.11 [95 % CI 0.08-0.14]; >18 years of age: 0.27 [95 % CI 0.24-0.30]).

CONCLUSION

CF-related AGT is common under 10 years of age. Our study suggests considering earlier AGT screening, starting from 5 years of age. This highlights the imperative for additional research for guideline adjustments and provides the opportunity for early intervention.

Continuous glucose monitoring and advanced glycation endproducts for prediction of clinical outcomes and development of cystic fibrosis-related diabetes in adults with CF

Introductions

Cystic fibrosis-related diabetes (CFRD) is associated with pulmonary decline, compromised nutritional status, and earlier mortality. Onset is often insidious, so screening for early detection of glycemic abnormalities is important. Continuous glucose monitoring (CGM) has been validated in people with CF and has been shown to detect early glycemic variability otherwise missed on 2-hour oral glucose tolerance testing (OGTT). We previously reported that CGM measures of hyperglycemia and glycemic variability are superior to hemoglobin A1c (HbA1c) in distinguishing those with and without CFRD. However, little is known about the long-term predictive value of CGM measures of glycemia for both the development of CFRD and their effect on key clinical outcomes such as weight maintenance and pulmonary function. In addition, there have been no studies investigating advanced glycation endproducts (AGE) assessed by skin autofluorescence in people with CF.

Methods

In this prospective observational study, CGM and HbA1c were measured at 2 to 3 time points 3 months apart in 77 adults with CF. Participants who did not have CFRD at the time of enrollment underwent OGTT at the baseline visit, and all participants had AGE readings at baseline. Follow up data including anthropometric measures, pulmonary function and CFRD status were collected by review of medical records 1- and 2-years after the baseline visits. We applied multivariable linear regression models correlating glycemic measures to change in key clinical outcomes (weight, BMI, FEV1) accounting for age, gender and elexacaftor/tezacaftor/ivacaftor (ETI) use. We also conducted logistic regression analyses comparing baseline glycemic data to development of CFRD during the 2-year follow up period.

Results

Of the 77 participants, 25 had pre-existing CFRD at the time of enrollment, and six participants were diagnosed with CFRD by the OGTT performed at the baseline visit. When adjusting for age, gender, and ETI use, multiple CGM measures correlated with weight and BMI decline after one year but not after two years. CGM and HbA1c at baseline did not predict decline in FEV1 (p>0.05 for all). In the 46 participants without a diagnosis of CFRD at baseline, two participants were diagnosed with CFRD over the following two years, but CGM measures at baseline did not predict progression to CFRD. Baseline AGE values were higher in individuals with CFRD and correlated with multiple measures of dysglycemia (HbA1c, AG, SD, CV, TIR, % time >140, >180, >250) as well as weight. AGE values also correlated with FEV1 decline at year 1 and weight decline at year 1 and year 2.

Conclusions

Several key CGM measures of hyperglycemia and glycemic variability were predictive of future decline in weight and BMI over one year in this population of adults with CF with and without CFRD. None of the baseline glycemic variables predicted progression to CFRD over 2 years. To our knowledge, this is the first report correlating AGE levels with key clinical and glycemic measures in CF. Limitations of these analyses include the small number of participants who developed CFRD (n=2) during the follow up period and the initiation of ETI by many participants, affecting their trajectory in weight and pulmonary function. These results provide additional data supporting the potential role for CGM in identifying clinically significant dysglycemia in CF. Future studies are needed to investigate CGM as a diagnostic and screening tool for CFRD and to understand the implications of AGE measures in this patient population.

Review of Computational Methods and Database Sources for Predicting the Effects of Coding Frameshift Small Insertion and Deletion Variations

Genetic variations (including substitutions, insertions, and deletions) exert a profound influence on DNA sequences. These variations are systematically classified as synonymous, nonsynonymous, and nonsense, each manifesting distinct effects on proteins. The implementation of high-throughput sequencing has significantly augmented our comprehension of the intricate interplay between gene variations and protein structure and function, as well as their ramifications in the context of diseases. Frameshift variations, particularly small insertions and deletions (indels), disrupt protein coding and are instrumental in disease pathogenesis. This review presents a succinct review of computational methods, databases, current challenges, and future directions in predicting the consequences of coding frameshift small indels variations. We analyzed the predictive efficacy, reliability, and utilization of computational methods and variant account, reliability, and utilization of database. Besides, we also compared the prediction methodologies on GOF/LOF pathogenic variation data. Addressing the challenges pertaining to prediction accuracy and cross-species generalizability, nascent technologies such as AI and deep learning harbor immense potential to enhance predictive capabilities. The importance of interdisciplinary research and collaboration cannot be overstated for devising effective diagnosis, treatment, and prevention strategies concerning diseases associated with coding frameshift indels variations.

An Update in Cystic Fibrosis-Related Diabetes in Children and Adolescents

This paper delineates several aspects of cystic fibrosis-related diabetes (CFRD)-a common complication of cystic fibrosis (CF). CFRD exhibits a predilection for older individuals with CF, yet it also extends its influence on children and adolescents. Scientific insights postulate a potential link between CFRD and the aberrant mucus production within the pancreas, thereby culminating in pancreatic insufficiency. This, in turn, perturbs the synthesis of insulin, a pivotal endocrine hormone responsible for the regulation of glycemic levels. Standardized protocols advocate for the systematic screening of CFRD among all individuals with CF, commencing at the age of 10 years using the oral glucose tolerance test (OGTT). Therapeutic modalities encompass insulin therapy, dietary adjustments, and the vigilant monitoring of glycemic parameters. The overarching objective is to maintain blood glucose levels within a targeted range to mitigate the advent of diabetic complications. Untreated or sub-optimally managed CFRD can precipitate a spectrum of deleterious health ramifications, encompassing cardiovascular afflictions, neuropathy, renal dysfunction, and ocular complications.

Reproducibility of in-home CFRD screening using continuous glucose monitoring and mixed meal tolerance test

Background

Cystic fibrosis related diabetes (CFRD) is associated with insulin-remediable pulmonary decline, so early detection is critical. Continuous glucose monitors (CGM) have shown promise in screening but are not recommended by clinical practice guidelines. Little is known about the reproducibility of CGM results for a given patient.

Methods

Twenty non-insulin treated adults and adolescents with CF placed an in-home CGM and wore it for two 14-day periods. Participants underwent a mixed meal tolerance test (MMTT) on day 5 of each 14-day period. Glycemic data from CGM 1 and CGM 2 were compared regarding published thresholds to define abnormality: percent time >140 mg/dL of ≥4.5%, percent time >140 mg/dL of >17.5%, and percent time >180 mg/dL of >3.4%. Results of the repeat MMTT were compared for peak glucose and 2-hour glucose thresholds: >140 mg/dL, >180 mg/dL, and >200 mg/dL.

Results

For percent time >140 mg/dL of ≥ 4.5%, five of 20 subjects had conflicting results between CGM 1 and CGM 2. For percent time >140 mg/dL of >17.5% and >180 mg/dL of >3.4%, only one of 20 subjects had conflicting results between CGM 1 and CGM 2. On the MMTT, few participants had a 2-hour glucose >140 mg/dL. Peak glucose >140 mg/dL, 180 mg/dL, and 200 mg/dL were more common, with 10-37% of participants demonstrating disagreement between CGM 1 and CGM 2.

Conclusions

Repeated in-home CGM acquisitions show reasonable reproducibility regarding the more stringent thresholds for time >140 mg/dL and >180 mg/dL. More data is needed to determine thresholds for abnormal mixed meal tolerance tests in CFRD screening.

Beyond the Lungs-Emerging Challenges in Adult Cystic Fibrosis Care

Cystic fibrosis (CF) is a multisystem disease. This article provides an up-to-date review of many of the nonrespiratory complications of CF, including mental health issues, nutritional and gastrointestinal problems, fertility issues, diabetes mellitus, bone health and musculoskeletal problems, liver disease, renal problems, and risk of malignancy. It highlights the recent impact of new therapies, including CF transmembrane conductance regulator modulators, on the nonrespiratory complications of CF and provides insights into the potential challenges faced by an aging population of adults with CF and their caregivers, including the potential future risk for cardiovascular disease.

Glycemic indices at night measured by CGM are predictive for a lower pulmonary function in adults but not in children with cystic fibrosis

INTRODUCTION

In patients with cystic fibrosis (CF), it is still unclear to which extent glucose abnormalities - preceding the diagnosis of cystic fibrosis related diabetes (CFRD) - are associated with pulmonary and nutritional outcome parameters. This study related circadian glycemic patterns to clinical outcomes in a group of CF patients not previously diagnosed with diabetes.

METHODS

Continuous glucose monitoring (CGM) readings (7 days) of 47 CF patients (26 children, 21 adults) with an impaired oral glucose tolerance test (OGTT) (n = 25) and/or increased Hb1Ac (> 5.5%) were analyzed. Biometric, pulmonary function and clinical parameters were retrospectively collected over a period of 1 year before (T-1) and 1 year after (T + 1) CGM (T0).

RESULTS

96% (45/47) of CGM readings showed glucose values > 140 mg/dL ≥ 4.5% of the time and at least one ≥ 200 mg/dL. In the pediatric cohort, no significant associations were found between CGM parameters and pulmonary and nutritional outcome parameters. In the adult cohort, an area under the curve (AUC) > 140 mg/dL and%-time > 140 mg/dL during the night were associated with a lower forced expiratory volume in 1 s (FEV1)% predicted (pp) at time of evaluation but not with change in FEV1pp.

CONCLUSION

This is the first study reporting the circadian glycemic pattern in children and adults at risk for CFRD. In the adult cohort an association between detection of abnormal glucose exposure and a lower FEV1pp was found. Our results support continued screening for glucose intolerance in patients with CF.

Standards of care for CFTR variant-specific therapy (including modulators) for people with cystic fibrosis

Cystic fibrosis (CF) has entered the era of variant-specific therapy, tailored to the genetic variants in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene. CFTR modulators, the first variant-specific therapy available, have transformed the management of CF. The latest standards of care from the European CF Society (2018) did not include guidance on variant-specific therapy, as CFTR modulators were becoming established as a novel therapy. We have produced interim standards to guide healthcare professionals in the provision of variant-specific therapy for people with CF. Here we provide evidence-based guidance covering the spectrum of care, established using evidence from systematic reviews and expert opinion. Statements were reviewed by key stakeholders using Delphi methodology, with agreement (≥80%) achieved for all statements after one round of consultation. Issues around accessibility are discussed and there is clear consensus that all eligible people with CF should have access to variant-specific therapy.

[Insulin pump therapy and continuous glucose monitoring]

This Guideline represents the recommendations of the Austrian Diabetes Association (ÖDG) on the use of diabetes technology (insulin pump therapy; continuous glucose monitoring, CGM; hybrid closed-loop systems, HCL; diabetes apps) and access to these technological innovations for people with diabetes mellitus based on current scientific evidence.

Continuous glucose monitoring versus self-monitoring of blood glucose in the management of cystic fibrosis related diabetes: A systematic review and meta-analysis

BACKGROUND

Treatment of cystic fibrosis related diabetes (CFRD) can improve outcomes and use of continuous glucose monitoring (CGM) can positively impact glycemic control. We conducted a systematic review to assess current evidence on CGM compared to self-monitoring of blood glucose (SMBG) in the management of CFRD to determine its effect on glycemic, pulmonary, non-pulmonary and quality of life outcomes.

METHODS

Using pre-defined selection criteria, we searched MEDLINE, Embase, CENTRAL, Evidence-Based Medicine Reviews, grey literature and six relevant journals for studies using CGM and/or SMBG in CFRD with greater than 6 weeks of follow-up and reported change in HbA1c. The primary outcome was weighted mean difference (WMD) in plasma HbA1c between CGM and SMBG groups. Secondary outcomes included exploring interrelationships between CGM metrics and effects on disease-specific pulmonary, non-pulmonary and quality of life outcomes.

RESULTS

A total of 1671 references were retrieved, 862 studies screened and 124 full-texts assessed for eligibility. No studies directly compared CGM to SMBG. A meta-analysis of seventeen studies of 416 individuals (CGM = 138, SMBG = 278) found CGM group had 4.1 mmol/mol (95% CI -7.9 to -0.30, p = 0.034) lower HbA1c compared to SMBG group. Most studies demonstrated moderate-to-high risk of bias. Publication bias was also present. Heterogeneity was high and meta-regression identified duration of follow-up in SMBG group as main contributor.

CONCLUSION

Our findings suggest use of CGM may be associated with improved glycemic control compared to SMBG in CFRD, however evidence of benefit on pulmonary, non-pulmonary and psychosocial outcomes are lacking.

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

Aims

Increasing evidence for benefit of early detection of cystic fibrosis related diabetes (CFRD) coupled with limitations of current diagnostic investigations has led to interest and utilisation of continuous glucose monitoring (CGM). We conducted a systematic review to assess current evidence on CGM compared to reference standard oral glucose tolerance test for the detection of dysglycemia in people with cystic fibrosis without confirmed diabetes.

Methods

MEDLINE, Embase, CENTRAL, Evidence-Based Medicine Reviews, grey literature and six relevant journals were searched for studies published after year 2000. Studies reporting contemporaneous CGM metrics and oral glucose tolerance test results were included. Outcomes on oral glucose tolerance tests were categorised into a) normal, b) abnormal (indeterminate and impaired) or c) diabetic as defined by American Diabetes Association criteria. CGM outcomes were defined as hyperglycemia (≥1 peak sensor glucose ≥ 200 mg/dL), dysglycemia (≥1 peak sensor glucose ≥ 140–199 mg/dL) or normoglycemia (all sensor glucose peaks < 140 mg/dL). CGM hyperglycemia in people with normal or abnormal glucose tolerances was used to define an arbitrary CGM-diagnosis of diabetes. The Quality Assessment of Diagnostic Accuracy Studies tool was used to assess risk of bias. Primary outcome was relative risk of an arbitrary CGM-diagnosis of diabetes compared to the oral glucose tolerance test.

Results

We identified 1277 publications, of which 19 studies were eligible comprising total of 416 individuals with contemporaneous CGM and oral glucose tolerance test results. Relative risk of an arbitrary CGM-diagnosis of diabetes compared to oral glucose tolerance test was 2.92. Studies analysed were highly heterogenous, prone to bias and inadequately assessed longitudinal associations between CGM and relevant disease-specific sequela.

Conclusions

A single reading > 200 mg/dL on CGM is not appropriate for the diagnosis of CFRD. Prospective studies correlating CGM metrics to disease-specific outcomes are needed to determine appropriate cut-points.

Comparison of Continuous Glucose Monitoring in Cystic Fibrosis Patients With or Without Pancreatic Exocrine Insufficiency

This study aimed to compare continuous glucose monitoring (CGM) in cystic fibrosis (CF) according to pancreatic exocrine status.CGM and oral glucose tolerance testing (OGTT) were realized annually over five years in people with CF (pwCF) aged≥10 years without cystic fibrosis-related diabetes (CFRD). CGM parameters in patients with normal glucose tolerance (NGT), impaired glucose tolerance (IGT), and newly diagnosed CFRD were compared according to presence of pancreatic sufficiency (PS) or insufficiency (PI).Overall, 547 OGTTs and 501 CGMs were performed in 147 CF patients, comprising 122 PI and 25 PS. In PS patients, 84% displayed NGT, 12% IGT, and 4% CFRD vs. 58%, 32%, and 10% (p=0.05) in PI. Among participants displaying normal OGTT, time in glucose range (70-140 mg/dl) was significantly increased, 97% (93, 99) vs. 92% (85, 96), p<0.001, and time above glucose range > 140 mg/dl significantly decreased, 1% (0, 2) % vs. 6% (2, 13), in patients with PS compared to those with PI. No significant differences were highlighted in patients with IGT.CGM revealed significant different glucose tolerance abnormalities in PI versus PS, which were undetected by standard 2-hour OGTT glucose.

Clinical practice versus guidelines for the screening of cystic fibrosis-related diabetes: A French survey from the 47 centers

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A French survey of clinical practices with the participation of all CF centers.

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Most CF centers used OGTT and CGM for CFRD screening.

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OGTT was conducted before 10 years of age in 73% of pediatric centers.

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One third of centers propose OGTT to sufficient pancreatic patients.

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69% of centers realized CGM in case of glucose tolerance abnormalities at OGTT.

This study aimed to analyze clinical practices concerning cystic fibrosis-related diabetes (CFRD) screening in France. A web-based questionnaire was distributed between December 1, 2020 and January 31, 2021 among 47 cystic fibrosis centers including pediatric, adult, and mixed units. In accordance with guidelines, 92.8% of CF centers performed annual oral glucose tolerance tests (OGTT). Overall, 86.3% of CF centers performed 1- and 2-hour blood glucose determinations following OGTT. The OGTT was conducted before 10 years of age in 73% of pediatric centers. Continuous glucose monitoring (CGM) and laboratory glycated hemoglobin were employed for CFRD screening in 86.5% and 50% of centers, respectively. CGM was carried out in 69% of centers after glucose tolerance abnormalities had been detected in OGTT. Most CF centers used OGTT and CGM for CFRD screening. Studies are required to assess CGM usefulness as a validated tool in CFRD screening.

Continuous Glucose Monitoring and HbA1c in Cystic Fibrosis: Clinical Correlations and Implications for CFRD Diagnosis

CONTEXT

The clinical utility and implications of continuous glucose monitoring (CGM) in cystic fibrosis (CF) are unclear.

OBJECTIVE

We examined the correlation between CGM measures and clinical outcomes in adults with CF, investigated the relationship between hemoglobin A1c (HbA1c) and CGM-derived average glucose (AG), and explored CGM measures that distinguish cystic fibrosis-related diabetes (CFRD) from normal and abnormal glucose tolerance.

METHODS

This prospective observational study included 77 adults with CF who had CGM and HbA1c measured at 2 to 3 time points 3 months apart.

RESULTS

Thirty-one of the 77 participants met American Diabetes Association-recommended diagnostic criteria for CFRD by oral glucose tolerance testing and/or HbA1c. In all participants, CGM measures of hyperglycemia and glycemic variability correlated with nutritional status and pulmonary function. HbA1c was correlated with AG (R2 = 0.71, P < 0.001), with no significant difference between this regression line and that previously established in type 1 and type 2 diabetes and healthy volunteers. Cutoffs of 17.5% time > 140 mg/dL and 3.4% time > 180 mg/dL had sensitivities of 87% and 90%, respectively, and specificities of 95%, for identifying CFRD. Area under the curve and percent of participants correctly classified with CFRD were higher for AG, SD, % time > 140, > 180, and > 250 mg/dL than for HbA1c.

CONCLUSION

CGM measures of hyperglycemia and glycemic variability are superior to HbA1c in distinguishing those with and without CFRD. CGM-derived AG is strongly correlated with HbA1c in adults with CF, with a similar relationship to other diabetes populations. Future studies are needed to investigate CGM as a diagnostic and screening tool for CFRD.

Cystic fibrosis-related diabetes: Prevalence, screening, and diagnosis

Cystic fibrosis-related diabetes (CFRD) is the most common comorbidity in patients with cystic fibrosis (CF). Prevalence of CFRD increases with age and is greater with severe mutations. Other risk factors associated with CFRD are female sex, pancreatic insufficiency, liver disease, need for gastrostomy tube feedings, history of bronchopulmonary aspergillosis, and poor pulmonary function. CFRD is related to worse clinical outcomes and increased mortality. Early diagnosis and treatment have been shown to improve clinical outcomes. Screening for CFRD is recommended with an annual oral glucose tolerance test (OGTT) starting at age 10 years. Diagnosis of CFRD is made by standard American Diabetes Association (ADA) criteria during baseline health. CFRD can also be diagnosed in individuals with CF during acute illness, while on enteral feeds, and after transplant. In this review we will discuss the epidemiology of CFRD and provide an overview of the advantages and pitfalls of current screening and diagnostic tests for CFRD.

The Relationship Between Continuous Glucose Monitoring and OGTT in Youth and Young Adults With Cystic Fibrosis

CONTEXT

Early glucose abnormalities in people with cystic fibrosis (PwCF) are commonly detected by continuous glucose monitoring (CGM). Relationships between these CGM abnormalities and oral glucose tolerance testing (OGTT) in PwCF have not been fully characterized.

OBJECTIVE

This work aimed to determine the relationship between CGM and common OGTT-derived estimates of β-cell function, including C-peptide index and oral disposition index (oDI) and to explore whether CGM can be used to screen for OGTT-defined prediabetes and cystic fibrosis-related diabetes (CFRD).

METHODS

PwCF not on insulin and healthy controls aged 6 to 25 years were enrolled in a prospective study collecting OGTT and CGM. A subset underwent frequently sampled OGTTs (fsOGTT) with 7-point glucose, insulin, and C-peptide measurements. Pearson correlation coefficient was used to test the association between select CGM and fsOGTT measures. Receiver operating curve (ROC) analysis was applied to CGM variables to determine the cutoff optimizing sensitivity and specificity for detecting prediabetes and CFRD.

RESULTS

A total of 120 participants (controls = 35, CF = 85), including 69 with fsOGTTs, were included. CGM coefficient of variation correlated inversely with C-peptide index (Cpeptide30-Cpeptide0/Glucose30-Glucose0) (r = -0.45, P < .001) and oDIcpeptide (C-peptide index)(1/cpep0) (r = -0.48, P < .0001). In PwCF, CGM variables had ROC - areas under the curve ranging from 0.43 to 0.57 for prediabetes and 0.47 to 0.6 for CFRD.

CONCLUSION

Greater glycemic variability on CGM correlated with reduced β-cell function. However, CGM performed poorly at discriminating individuals with and without OGTT-defined CFRD and prediabetes. Prospective studies are now needed to determine how well the different tests predict clinically relevant nonglycemic outcomes in PwCF.

Continuous glucose monitoring systems for monitoring cystic fibrosis-related diabetes

BACKGROUND

Cystic fibrosis (CF) is one of the most common life-shortening autosomal-recessive genetic conditions with around 100,000 people affected globally. CF mainly affects the respiratory system, but cystic fibrosis-related diabetes (CFRD) is a common extrapulmonary co-morbidity and causes excess morbidity and mortality in this population. Continuous glucose monitoring systems (CGMS) are a relatively new technology and, as yet, the impact of these on the monitoring and subsequent management of CFRD remains undetermined.

OBJECTIVES

To establish the impact of insulin therapy guided by continuous glucose monitoring compared to insulin therapy guided by other forms of glucose data collection on the lives of people with CFRD.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. Date of latest search: 23 September 2021. We also searched the reference lists of relevant articles and reviews and online trials registries. Date of last search: 23 September 2021.

SELECTION CRITERIA

Randomised controlled studies comparing insulin regimens led by data from CGMS (including real-time or retrospective data, or both) with insulin regimens guided by abnormal blood glucose measurements collected through other means of glycaemic data collection in people with CFRD. Studies with a cross-over design, even with a washout period between intervention arms, are not eligible for inclusion due to the potential long-term impact of each of the interventions and the potential to compromise the outcomes of the second intervention.

DATA COLLECTION AND ANALYSIS

No studies were included in the review, meaning that no data were available to be collected for analysis.

MAIN RESULTS

Review authors screened 14 studies at the full-text stage against the review's inclusion criteria. Consequently, seven were excluded due to the study type being ineligible (not randomised), two studies were excluded due to their cross-over design, and two studies was excluded since the intervention used was not eligible and one was a literature review. One study in participants hospitalised for a pulmonary exacerbation is ongoing. Investigators are comparing insulin dosing via insulin pump with blood sugar monitoring by a CGMS to conventional diabetes management with daily insulin injections (or on an insulin pump if already on an insulin pump in the outpatient setting) and capillary blood glucose monitoring. The participants in the control arm will wear a blinded continuous glucose monitoring system for outcome assessment. In addition to this, one further study is still awaiting classification, and will be screened to determine whether it is eligible for inclusion, or is to be excluded, in an update of this review.

AUTHORS' CONCLUSIONS

No studies were included in the review, indicating that there is currently insufficient evidence to determine the impact of insulin therapy guided by CGMS compared to insulin therapy guided by other forms of glucose data collection on the lives of people with CFRD, nor on potential adverse effects of continuous glucose monitoring in this context. Randomised controlled studies are needed to generate evidence on the efficacy and safety of continuous glucose monitoring in people with CFRD. There is one relevant ongoing study that may be eligible for inclusion in a future update of this Cochrane Review, and whose results may help answer the review question.

Spontaneous and iatrogenic hypoglycemia in cystic fibrosis

Spontaneous episodes of hypoglycemia can occur in people with cystic fibrosis (CF) without diabetes, who are not on glucose lowering medications. Spontaneous hypoglycemia in CF could occur both in the fasting or postprandial state (reactive hypoglycemia). The pathophysiology of fasting hypoglycemia is thought to be related to malnutrition and increased energy expenditure in the setting of inflammation and acute infections. Reactive hypoglycemia is thought to be due to impaired first phase insulin release in response to a glucose load, followed by a delayed and extended second phase insulin secretion; ineffective counterregulatory response to dropping glucose levels may also play a role. The overall prevalence of spontaneous hypoglycemia varies from 7 to 69% as examined with oral glucose tolerance test (OGTT) or with continuous glucose monitoring (CGM) under free living conditions. Spontaneous hypoglycemia in CF is associated with worse lung function, higher hospitalization rates, and worse clinical status. In addition, patients with CF related diabetes on glucose-lowering therapies are at risk for iatrogenic hypoglycemia. In this article, we will review the pathophysiology, prevalence, risk factors, clinical implications, and management of spontaneous and iatrogenic hypoglycemia in patients with CF.

Abnormal glucose tolerance and lung function in children with cystic fibrosis. Comparing oral glucose tolerance test and continuous glucose monitoring

BACKGROUND

Cystic fibrosis (CF) related diabetes (CFRD) is a common complication of CF. CFRD is associated with declining lung function even before its onset. Regular screening for CFRD using oral glucose tolerance test (OGTT) is recommended. Additionally, continuous glucose monitoring (CGM) has surfaced as a possible surveillance method, but evidence for its use and concordance with OGTT has not been established.

METHODS

Children were prospectively recruited at CF center Lund to undergo both intermittent scan CGM (isCGM) and OGTT. Lung function was evaluated by spirometry and multiple breath washout. Demographic and clinical data were collected from the Swedish national CF registry.

RESULTS

32 patients participated in the study, yielding 28 pairs of isCGMs and OGTTs. The OGTTs showed that two patients met the criteria of CFRD, seven had impaired glucose tolerance (IGT) and indeterminate glycemia (INDET) was found in eleven cases. The isCGM percent of measurements >8mmol/L and the number of peaks per day >11 mmol/L have correlations with intermediate OGTT glucose time points, but not the 2hour glucose value. Patients with abnormal glucose tolerance (AGT) had lower lung function than those with normal glucose tolerance demonstrated by both FEV1% predicted and lung clearance index (LCI).

CONCLUSION

Correlations can be found between isCGM and OGTT in regards to the latter's intermediate time points. LCI demonstrates as well as FEV1% of predicted, worse lung function in children and adolescents with abnormal glucose tolerance in CF.

Hypoglycemia in cystic fibrosis: Prevalence, impact and treatment

Hypoglycemia is a common and feared complication of insulin therapy. As in type 1 and type 2 diabetes, people with cystic fibrosis related diabetes are also at risk for hypoglycemia related to insulin therapy. Spontaneous hypoglycemia is also common in patients with CF without diabetes, who are not on glucose lowering medications. Spontaneous hypoglycemia in CF may also occur during or after an oral glucose tolerance test. In this review, we will discuss the definition, epidemiology, pathophysiology and impact of hypoglycemia, with a focus on people with cystic fibrosis. We will also review strategies to manage and prevent hypoglycemia.

Overview of Atypical Diabetes

Although type 1 diabetes mellitus and, to a lesser extent, type 2 diabetes mellitus, are the prevailing forms of diabetes in youth, atypical forms of diabetes are not uncommon and may require etiology-specific therapies. By some estimates, up to 6.5% of children with diabetes have monogenic forms. Mitochondrial diabetes and cystic fibrosis related diabetes are less common but often noted in the underlying disease. Atypical diabetes should be considered in patients with a known disorder associated with diabetes, aged less than 25 years with nonautoimmune diabetes and without typical characteristics of type 2 diabetes mellitus, and/or with comorbidities associated with atypical diabetes.

Cystic fibrosis-related diabetes: an update on pathophysiology, diagnosis, and treatment

Cystic fibrosis (CF) is a highly prevalent autosomal recessive disorder that is caused by mutations in the CF transmembrane conductance regulator (CFTR) gene (7q31.2), which encodes the CFTR chloride-anion channel that is expressed in several tissues. Life expectancy has increased significantly over the past few decades due to therapeutic advances and early diagnosis through neonatal screening. However, new complications have been identified, including CF-related diabetes (CFRD). The earliest detectable glycemic abnormality is postprandial hyperglycemia that progresses into fasting hyperglycemia. CFRD is associated with a decline in lung function, impairments in weight gain and growth, pubertal development, and increased morbidity and mortality. Annual screening with oral glucose tolerance test is recommended beginning at the age of 10, and screenings are recommended for any age group during the first 48 h of hospital admission. Fasting plasma glucose levels ≥126 mg/dL (7.0 mmol/L) or 2-h postprandial plasma glucose levels ≥200 mg/dL (11.1 mmol/L) that persist for more than 48 h are diagnostic criteria for CFRD. Under stable health condition, the diagnosis is made when laboratory abnormalities in accordance with the American Diabetes Association criteria are detected for the first time; however, levels of HbA1c <6.5% do not rule out the diagnosis. Treatment for CFRD includes insulin replacement and a hypercaloric and hyperproteic diet that does not restrict carbohydrates, fats or salt, and diabetes self-management education. The most important CFRD complications are nutritional and pulmonary disease deterioration, though the microvascular complications of diabetes have already been described.