Natural history of glucose intolerance in patients with cystic fibrosis: ten-year prospective observation program

Burkholderia cepacia in cystic fibrosis children and adolescents: overall survival and immune alterations

Background

In current literature there are only scarce data on the host inflammatory response during Burkholderia cepacia complex (Bcc) persistence. The primary objective of the present research was to carry out cross-sectional analyses of biomarkers and evaluate disease progression in cystic fibrosis (CF) patients with chronic Bcc infection and pathogen-free ones. The secondary aim was to assess prospectively overall survival of the study participants during up to 8 years of follow-up.

Methods

The study included 116 paediatric patients with CF; 47 CF patients were chronically infected with Bcc, and 69 individuals were Bcc free. Plasma and sputum biomarkers (neutrophil elastase, MMP-8, MMP-9, MMP-12, IL-2, IL-4, IL-6, IL-8, IL-10, IL-18, IL-22, IL-23, IL-17, IFN-γ, TGFβ1, TNF-α) were analysed using commercially available kits. Besides, inhibitory effect of dexamethasone on proliferative response of PHA-stimulated peripheral blood lymphocytes had been assessed.

Results

Bcc infected patients did not differ from Bcc free ones in demographic and clinical parameters, but demonstrated an increased rate of glucose metabolism disturbances and survival disadvantage during prolong follow-up period. Biomarkers analyses revealed elevated TNF-α and reduced IL-17F levels in sputum samples of Bcc infected patients. These patients also demonstrated improvement of peripheral blood lymphocyte sensitivity to steroid treatment and reduction in plasma pro-inflammatory (IL-17F and IL-18) and anti-inflammatory (TGFβ1 and IL-10) cytokine concentrations.

Conclusions

Reduction in IL-17F levels may have several important consequences including increase in steroid sensitivity and glycemic control disturbances. Further investigations are needed to clarify the role of IL-17 cytokines in CF complication development. Low plasma TGFβ1 and IL-10 levels in Bcc infected group may be a sign of subverted activity of regulatory T cells. Such immune alterations may be one of the factors contributing to the development of the cepacia syndrome.

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.

Insulinogenic index and early phase insulin secretion predict increased risk of worsening glucose tolerance and of cystic fibrosis-related diabetes

OBJECTIVE

Measures of stimulated insulin secretion are emerging as important predictors of diabetes mellitus in at-risk populations. We analyzed the utility of clinical estimates of insulin secretion in a prospective cohort at risk for cystic fibrosis-related diabetes (CFRD).

METHODS

We divided the profiles of 189 people with CF (pwCF) followed longitudinally in the Montreal CF cohort (mean follow up 6.6 ± 1.2 years) according to quartiles of the insulinogenic index (IGI; (I₃₀-I₀)/(G₃₀-G₀)); area under the curve for insulin normalized for glucose (AUC_ins/glu), and HOMA-B at baseline to compare clinical characteristics and risk of CFRD according to quartiles for each measure. We also compared characteristics of 40 pwCF found to have de novo CFRD at baseline.

RESULTS

At baseline, IGI and AUC_ins/glu were lower in subjects with de novo CFRD and those who later developed CFRD than those who never developed CFRD (p < 0.0001 for each). Subjects with the lowest quartiles of IGI, AUC_ins/glu, and AUC_{ins/glu 0-30} had increased risk of developing CFRD by Kaplan-Meier analysis (p = 0.0244, p = 0.0024, and p = 0.0338, respectively). There was no significant difference in risk between quartiles of HOMA-B. Subjects in the lowest quartile of IGI showed a significant increase in 2-hour OGTT glucose and AUC_glu between the initial and final study visits (p = 0.0027 and p = 0.0044, respectively).

CONCLUSION

IGI is easily measured in a clinical setting and needs to be validated in prospective studies as a potential tool to improve risk stratification in CFRD with direct relevance to pathogenesis.

Cystic fibrosis related diabetes (CFRD) in the era of modulators: A scoping review

Cystic fibrosis-related diabetes (CFRD) is a common complication of CF that increases in incidence as patients age. Poor glycemic control has been shown to negatively impact lung function and weight, resulting in higher risk of recurrent pulmonary exacerbations. With the advent of highly effective modulator therapies (HEMT), patients with CF are living longer and healthier lives. Consequently, CFRD and its microvascular complications are rising in prominence, becoming one of the most urgent clinical concerns. As HEMT were developed with the primary focus of improving pulmonary outcomes, it is not clear from the original phase III studies what the short- or long-term benefits of modulators might be on CFRD development and trajectory. In this review, we will examine the pathophysiology of CFRD, summarize and synthesize the available evidence of HEMT impact on CFRD and describe the emerging research needs in this field.

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.

Marginal association of fasting blood glucose with the risk of cystic fibrosis-related diabetes

OBJECTIVES

Cystic fibrosis-related diabetes (CFRD) may be diagnosed by fasting blood glucose ≥ 7.0 mmol/L and/or glucose ≥ 11.1 mmol/L following oral glucose tolerance test (OGTT). We compared the role of fasting and stimulated glucose for diagnosis of CFRD.

METHODS

We performed a cross-sectional review of the prevalence of fasting glycemic abnormalities and Kaplan-Meier survival analysis of risk of progression to CFRD according to baseline fasting glucose in the prospective Montreal Cystic Fibrosis Cohort.

RESULTS

Isolated fasting hyperglycemia was detected in only 8% of participants at study onset. Eighty percent of subjects had isolated post-challenge hyperglycemia on their first OGTT meeting criteria for CFRD. Kaplan Meier survival analysis demonstrated that impaired fasting glucose (IFG) alone is not a risk factor for CFRD. Subjects with combined IFG and impaired glucose tolerance at baseline (IGT) had the highest risk of progression to CFRD.

CONCLUSION

Post-prandial elevations in blood glucose are more common at diagnosis of CFRD. While IGT is a significant risk factor for CFRD, IFG alone is uncommon and does not increase the risk of CFRD. Patients with both IGT and IFG have the highest risk of CFRD.

Combined Indeterminate and Impaired Glucose Tolerance Is a Novel Group at High Risk of Cystic Fibrosis-Related Diabetes

BACKGROUND

Indeterminate glycemia (INDET) and impaired glucose tolerance (IGT) are independently associated with cystic fibrosis-related diabetes (CFRD) risk. We determined whether patients meeting both criteria have increased risk of diabetes in 2 separate adult cohorts.

METHODS

The Montreal Cystic Fibrosis Cohort (MCFC; n = 293 baseline and 198 for prospective analysis excluding subjects identified with incident CFRD at baseline) and the Lyon cystic fibrosis cohort [Determination of the Predictive Factors in the Reversibility or the Aggravation in the Disorders of the Glucose Metabolism in Cystic Fibrosis Patients (DIAMUCO); n = 144/105] are prospective observational cohorts.

RESULTS

In the MCFC and DIAMUCO cohorts, mean age was 25.5 ± 7.7 and 25.0 ± 8.6 years; body mass index, 21.7 ± 3.0 and 20.2 ± 2.2 kg/m2; percentage of forced expiratory volume expired in 1 sec, 73.2 ± 22.1 and 62.5 ± 21.9; and follow-up, 6.9 ± 3.8 and 2.4 ± 1.2 years, respectively. In the MCFC cohort, the IGT only and combined INDET and IGT (INDET + IGT) groups had greater risk of CFRD (P = 0.0109). In the DIAMUCO cohort, there was lower diabetes-free survival in the INDET + IGT group (P = 0.0105). In both cohorts, CFRD risk ranged from 17% in normal glucose tolerance patients up to 42% to 56% in patients with INDET + IGT.

CONCLUSION

Patients who meet combined criteria have a higher risk of developing diabetes probably justifying closer follow-up.

Association between HbA1c and the development of cystic fibrosis-related diabetes

AIMS

To examine HbA_1c as a predictor of risk for future development of cystic fibrosis-related diabetes and to assess the association with the development of retinopathy in people with cystic fibrosis-related diabetes.

METHODS

A 7-year retrospective longitudinal study was conducted in 50 adults with cystic fibrosis, comparing oral glucose tolerance test results with HbA_1c values in predicting the development of cystic fibrosis-related diabetes. Retinal screening data were also compared with HbA_1c measurements to assess microvascular outcome.

RESULTS

An HbA_1c value ≥37 mmol/mol (5.5%; hazard ratio 3.49, CI 1.5-8.1) was significantly associated with the development of dysglycaemia, as defined by the oral glucose tolerance test over a 7-year period. Severity of diabetic retinopathy was associated with a higher HbA_1c and longer duration of cystic fibrosis-related diabetes.

CONCLUSION

There is a link between HbA_1c level and the future development of dysglycaemia in cystic fibrosis based on oral glucose tolerance test, as well as microvascular outcomes. Although current guidance does not advocate the use of HbA_1c as a diagnostic tool in cystic fibrosis-related diabetes, it may be of clinical use in determining individuals at risk of future development of cystic fibrosis-related diabetes.

Impaired glucose tolerance, body mass index and respiratory function in patients with cystic fibrosis: A systematic review

OBJECTIVES

This systematic review aims to evaluate body mass index (BMI) and forced expiratory volume in one second (FEV₁ ) in patients with cystic fibrosis (CF) diagnosed with impaired glucose tolerance (IGT) compared to those with normal glucose tolerance (NGT). The significance of this topic stems from concern that individuals with CF and IGT may have an overall worse clinical status as indicated by BMI and FEV₁ .

DATA SOURCE

An exhaustive literature search was completed between July 2017 and September 2017 using PubMed, CINAHL, Web of Science, Dissertations & Theses, PsycINFO, and Open Grey. Studies were limited to human subjects with CF. There were no restrictions on publication date, study design or language.

STUDY SELECTION

Included studies examined BMI and FEV₁ as outcome measures in individuals with CF and IGT compared to those with NGT. After screening for inclusion criteria, 12 observational studies met the specified conditions.

RESULTS

Two studies showed a significantly worse BMI and FEV₁ in subjects with CF and IGT compared to those with NGT. The remaining 10 studies found no significant associations with BMI and FEV₁ in subjects with CF and IGT compared to NGT.

CONCLUSION

Although this review does not prove cause and effect, BMI and FEV₁ are important outcome measures in patients with CF. Considering the inconclusive findings, practitioners should individualize care for this patient population. Additional research should focus on clinical status and interventions/treatment for individuals with CF and IGT.

Glucose tolerance in Canadian and French cystic fibrosis adult patients

Cystic fibrosis (CF)-related diabetes is associated with increased mortality. We analysed the clinical and glycemic profiles of two cohorts of patients treated according to the same guidelines in France and Canada. To investigate incidence differences in phenotypic and glucose abnormalities and to explore the evolution over a 4-year follow-up period, two cohorts of 224 Canadian and 147 French adult CF patients (≥18 years) without treated CF-related diabetes (CFRD) were followed over a 4 year period. In each of these groups, we investigated the longitudinal relationship between glucose tolerance and pulmonary function. An annual 2-hour oral glucose tolerance test was performed: fasting blood glucose (G0) and 2-h blood glucose (G2) were measured. Patients were classified at inclusion according to their glucose tolerance status: Normal glucose tolerant, abnormal glucose tolerant or de novo CFRD. Age, sex ratio and proportion of F508del homozygous patients were not statistically different between both cohorts. Canadian patients had better pulmonary function (median %FEV1 (IQR): 71.0 (55.0–82.0) vs. 64.0 (40.0–78.0), p < 0.001) and greater body mass index (BMI; median BMI in kg/m²) (IQR) 21.1 (19.5–22.8) vs. 19.9 (18.4–21.4), p < 0.001). Glucose values: G0 (5.4 (5.0–5.9) vs. 4.8 (4.5–5.1) mmol/L, p < 0.001) and G2 (7.6 (5.8–9.7) vs. 6.5 (5.2–8.5) mmol/L, p = 0.001) were higher in the Canadian cohort translating into a higher incidence of de novo CFRD diagnosis (19.2 vs. 9.8%, p = 0.003). Decline in FEV1 over time was not different between patients according to glucose tolerance groups. Despite higher glucose levels and incidence of de novo CFRD, Canadian CF patients have a better lung function and a higher BMI than French patients. In spite of these differences between the cohorts, the decline in FEV1 in patients with abnormal glucose tolerance is similar between these groups.

Glucose intolerance in children with cystic fibrosis: a developing country's perspective

Background Cystic fibrosis-related diabetes (CFRD) is a common comorbidity reported in patients with cystic fibrosis (CF). There is a dearth of data on glucose intolerance or CFRD in children with CF from developing countries. So, we planned to study the prevalence of abnormal glucose tolerance (AGT) in children with CF and its relation with the duration and severity of CF. Methods We performed an oral glucose tolerance test (OGTT) on children (2-18 years old) having CF for at least 6 months. Two-hour plasma glucose levels on OGTT were correlated with various disease-related factors. Results Out of the 25 children enrolled, there were 18 boys and seven girls. The mean age and duration of CF were 7.9±4.3 and 3.16±2.5 years, respectively. AGT was observed in 16 (64%) children with CF including three (12%) children with CFRD. Children with a duration of CF of 3 years had significantly higher prevalence (81.8%) of AGT when compared with duration ≤3 years (p-value<0.05). Twelve out of 17 (70.6%) children were colonized with Pseudomonas and 12 out of 15 (80%) children >6 years of age had AGT. There was a positive correlation of 2-h glucose value on OGTT with duration of CF and number of hospitalizations with acute pulmonary exacerbations. Conclusions The majority of children having CF for >3 years and/or age >6 years developed AGT. In our clinical setting, an annual screening with OGTT to detect AGT may be required at an early age and duration of CF.

Oral glucose tolerance test and continuous glucose monitoring to assess diabetes development in cystic fibrosis patients

INTRODUCTION

Patients with cystic fibrosis (CF) undergo a slow and progressive process toward diabetes. Oral glucose tolerance test (OGTT) is recommended to diagnose impaired glucose levels in these patients. Continuous glucose monitoring (CGM) measures glucose profiles under real-life conditions.

OBJECTIVE

To compare OGTT and CGM results in CF patients.

METHODS

Paired OGTT and 6-day CGM profiles (146.2±9.1h/patient) were performed in 30 CF patients aged 10-18 years.

RESULTS

According to OGTT, 14 patients had normal glucose tolerance (NGT), 14 abnormal glucose tolerance (AGT), and two cystic fibrosis-related diabetes (CFRD). In 27 patients (13 NGT, 13 AGT, 1 CFRD), CGM showed glucose values ranging from 140 to 200mg/dL during similar monitoring times (2%-14% with NGT, 1%-16.9% with AGT, and 3% with CFRD). Glucose peak levels ≥200mg/dL were seen in seven patients (3 NGT, 3 AGT, 1 CFRD). According to CGM, two patients had all glucose values under 140mg/dL (1 NGT, 1 AGT). Seventeen patients had glucose levels ranging from 140 to 200mg/dL (10 NGT, 6 AGT, 1 CFRD). Ten patients (3 NGT, 7 AGT) had glucose values ≥200mg/dL for ≤1% of the monitoring time and one (CFRD) for >1% of the monitoring time.

CONCLUSIONS

OGTT results did not agree with those of the CGM. CGM allows for diagnosis of glucose changes not detected by OGTT. Such changes may contribute to optimize pre-diabetes management in CF patients.

Abnormal Glucose Tolerance in Infants and Young Children with Cystic Fibrosis

RATIONALE

In cystic fibrosis, abnormal glucose tolerance is associated with decreased lung function and worsened outcomes. Translational evidence indicates that abnormal glucose tolerance may begin in early life.

OBJECTIVES

To determine whether very young children with cystic fibrosis have increased abnormal glucose tolerance prevalence compared with control subjects. The secondary objective was to compare area under the curve for glucose and insulin in children with cystic fibrosis with control subjects.

METHODS

This is a prospective multicenter study in children ages 3 months to 5 years with and without cystic fibrosis.

MEASUREMENTS AND MAIN RESULTS

Oral glucose tolerance testing with glucose, insulin, and C-peptide was sampled at 0, 10, 30, 60, 90, and 120 minutes. Twenty-three children with cystic fibrosis and nine control subjects had complete data. All control subjects had normal glucose tolerance. Nine of 23 subjects with cystic fibrosis had abnormal glucose tolerance (39%; P = 0.03). Of those, two met criteria for cystic fibrosis-related diabetes, two indeterminate glycemia, and six impaired glucose tolerance. Children with cystic fibrosis failed to exhibit the normal increase in area under the curve insulin with age observed in control subjects (P < 0.01), despite increased area under the curve glucose (P = 0.02).

CONCLUSIONS

Abnormal glucose tolerance is notably prevalent among young children with cystic fibrosis. Children with cystic fibrosis lack the normal increase in insulin secretion that occurs in early childhood despite increased glucose. These findings demonstrate that glycemic abnormalities begin very early in cystic fibrosis, possibly because of insufficient insulin secretion.

Screening of glucose metabolism derangements in pediatric cystic fibrosis patients: how, when, why

Diabetes mellitus is the most common comorbidity in cystic fibrosis (CF), occurring in a variable number of children and adolescents. Glucose metabolism derangements (GMDs) are responsible for a negative impact on the general health status of CF patients. Screening of GMDs is important since the youngest age and should be performed by means of OGTT, including its intermediate times, that could detect other non-traditional GMDs. Insulin treatment, administered before overt diabetes, could be beneficial in reducing the number of pulmonary infections, in improving both pulmonary function and nutritional status. Early screening of GMDs in pediatric age can exert an important preventing role regarding all aspects of health status of patients with CF.

The development of diabetes among Danish cystic fibrosis patients over the last two decades

OBJECTIVE

Cystic fibrosis (CF)-related diabetes (CFRD) is correlated with age and has been associated with a decline in body mass index (BMI), pulmonary function, and survival. Over the last two decades, the focus has been on the early diagnosis and treatment of diabetes; therefore, in this study, we evaluated the status of the current clinical condition and survival in our CF population. In addition, we also aimed to investigate the incidence of diabetes among adolescence over time and to identify characteristics associated with early diabetes onset.

METHODS

A retrospective chart review of a birth cohort consisting of 161 CF patients born between 1975 and 1994 and followed until 2011.

RESULTS

Over two decades, the incidence of CFRD among 11- to 16-year-old children remained unchanged at 12-14%, while the proportion of children with chronic pulmonary infection at age 10 declined from 31 to 8% (p < 0.001). Severe CF-mutation, i.e., group I and II mutations, were associated with diabetes (p = 0.003). Female gender was borderline associated with diabetes among adolescents (p = 0.06). No significant worsening in pulmonary function, BMI or survival was identified when comparing CFRD patients to CF patients without CFRD.

CONCLUSIONS

The incidence of diabetes among adolescence with CF has not changed over the last two decades. Severe CF mutations are a risk factor for CFRD, and female gender is borderline associated with CFRD among adolescents. Pulmonary function, BMI and survival were comparable regardless of the onset of CFRD.

Management of endocrine disease: Cystic fibrosis-related diabetes: novel pathogenic insights opening new therapeutic avenues

Cystic fibrosis (CF) is a recessive genetic disease caused by mutations in the CF transmembrane conductance regulator (CFTR). CFTR is primarily present in epithelial cells of the airways, intestine and in cells with exocrine and endocrine functions. Mutations in the gene encoding the channel protein complex (CFTR) cause alterations in the ionic composition of secretions from the lung, gastrointestinal tract, liver, and also the pancreas. CF-related diabetes (CFRD), the most common complication of CF, has a major detrimental impact on pulmonary function, nutrition and survival. Glucose derangements in CF seem to start from early infancy and, even when the pathophysiology is multifactorial, insulin insufficiency is clearly a major component. Consistently, recent evidence has confirmed that CFTR is an important regulator of insulin secretion by islet β-cells. In addition, several other mechanisms were also recognized from cellular and animals models also contributing to either β-cell mass reduction or β-cell malfunction. Understanding such mechanisms is crucial for the development of the so-called 'transformational' therapies in CF, including the preservation of insulin secretion. Innovative therapeutic approaches aim to modify specific CFTR mutant proteins or positively modulate their function. CFTR modulators have recently shown in vitro capacity to enhance insulin secretion and thereby potential clinical utility in CFDR, including synergistic effects between corrector and potentiator drugs. The introduction of incretins and the optimization of exocrine pancreatic replacement complete the number of therapeutic options of CFRD besides early diagnosis and implementation of insulin therapy. This review focuses on the recently identified pathogenic mechanisms leading to CFRD relevant for the development of novel pharmacological avenues in CFRD therapy.

High variability in oral glucose tolerance among 1,128 patients with cystic fibrosis: a multicenter screening study

Background

In cystic fibrosis, highly variable glucose tolerance is suspected. However, no study provided within-patient coefficients of variation. The main objective of this short report was to evaluate within-patient variability of oral glucose tolerance.

Methods

In total, 4,643 standardized oral glucose tolerance tests of 1,128 cystic fibrosis patients (median age at first test: 15.5 [11.5; 21.5] years, 48.8% females) were studied. Patients included were clinically stable, non-pregnant, and had at least two oral glucose tolerance tests, with no prior lung transplantation or systemic steroid therapy. Transition frequency from any one test to the subsequent test was analyzed and within-patient coefficients of variation were calculated for fasting and two hour blood glucose values. All statistical analysis was implemented with SAS 9.4.

Results

A diabetic glucose tolerance was confirmed in 41.2% by the subsequent test. A regression to normal glucose tolerance at the subsequent test was observed in 21.7% and to impaired fasting glucose, impaired glucose tolerance or both in 15.2%, 12.0% or 9.9%. The average within-patient coefficient of variation for fasting blood glucose was 11.1% and for two hour blood glucose 25.3%.

Conclusion

In the cystic fibrosis patients studied, a highly variable glucose tolerance was observed. Compared to the general population, variability of two hour blood glucose was 1.5 to 1.8-fold higher.

Diagnosis and treatment of endocrine comorbidities in patients with cystic fibrosis

PURPOSE OF REVIEW

The aim of this review is to provide an update on various relevant endocrine aspects of care in adolescents and adults with cystic fibrosis.

RECENT FINDINGS

As life expectancy in cystic fibrosis has continuously improved, endocrine complications have become more apparent. The common endocrine complications include cystic fibrosis related diabetes, cystic fibrosis related bone disease, vitamin D deficiency and poor growth and pubertal development. Thyroid and adrenal disorders have also been reported, although the prevalence appears to be less common.

SUMMARY

Endocrine diseases are an increasingly recognized complication that has a significant impact on the overall health of individuals with cystic fibrosis. This review summarizes the updated screening and management of endocrine diseases in the cystic fibrosis population.

Cystic fibrosis related diabetes

Improved life expectancy in cystic fibrosis (CF) has led to an expanding population of adults with CF, now representing almost 50 % of the total CF population. This creates new challenges from long-term complications such as diabetes mellitus (DM), a condition that is present in 40 %-50 % of adults with CF. Cystic fibrosis-related diabetes (CFRD) results from a primary defect of insulin deficiency and although sharing features with type 1 (DM1) and type 2 diabetes (DM2), it is a clinically distinct condition. Progression to diabetes is associated with poorer CF clinical outcomes and increased mortality. CFRD is not associated with an increased risk of cardiovascular disease and the prevalence of microvascular complications is lower than DM1 or DM2. Rather, the primary goal of insulin therapy is the preservation of lung function and optimization of nutritional status. There is increasing evidence that appropriate screening and early intervention with insulin can reverse weight loss and improve pulmonary function. This approach may include targeting postprandial hyperglycemia not detected by standard diagnostic tests such as the oral glucose tolerance test. Further clinical research is required to guide when and how much to intervene in patients who are already dealing with the burden of one chronic illness.

Low glycaemic index dietary interventions in youth with cystic fibrosis: a systematic review and discussion of the clinical implications

A systematic review was conducted to assess what is known about the effect of low glycaemic index (GI) diets on glycaemic control, weight and quality of life in youth with cystic fibrosis (CF). Eligibility criteria were systematic reviews, randomised and non-randomised trials of low GI dietary interventions in CF. Outcomes examined were glycaemic control, quality of life, anthropometry and respiratory function. Reference lists were manually searched and experts in the field were consulted. Four studies met the eligibility criteria; two were excluded because they did not include data on any of the outcomes. The remaining two were studies that examined GI secondary to any other intervention: one used GI as a factor in enteral feeds and the other incorporated low GI dietary education into its treatment methodology. There is insufficient evidence to recommend use of low GI diets in CF. Since there is evidence to support use of low GI diets in type 1, type 2 and gestational diabetes, low GI diets should be tested as an intervention for CF. The potential risks and benefits of a low GI diet in CF are discussed.

A review of abdominal organ transplantation in cystic fibrosis

With advances in medical treatments, patients with CF are having improved quality of life and living longer. Although pulmonary disease is still the leading cause of morbidity and mortality, this longevity has allowed for the development of other organ dysfunction, mainly liver and pancreas. This review discusses the abdominal organ complications and the role of abdominal organ transplantation in CF. Liver failure and portal hypertension complications are the most common indicators for liver transplantation in CF, and five-yr survival for isolated liver transplantation is >80%. Deficiency of pancreatic enzymes is almost universal and up to 40% of patients with CF can develop insulin-dependent diabetes, although the role of pancreas transplantation is less clear and needs further research. Finally, the need for lung transplantation should always be assessed and considered in combination with liver transplantation on a case-by-case basis.

Recent trends in cystic fibrosis-related diabetes

PURPOSE OF REVIEW

To provide an updated literature review highlighting important aspects of cystic fibrosis-related diabetes (CFRD) including epidemiology, pathogenesis, complications, screening, and management.

RECENT FINDINGS

Although CFRD continues to be associated with increased rates of mortality in the cystic fibrosis (CF) population, this has improved over the past several years, and the previous sex difference is no longer present. Recent studies support that CFRD is primarily caused by insulin deficiency due to loss of beta cells, which may occur via a number of mechanisms including oxidative stress. Aggressive screening programs with oral-glucose tolerance testing and early treatment with insulin for patients with CFRD with or without fasting hyperglycemia have led to improvements in nutritional states and lung function. Oral agents do not appear to be effective in CFRD.

SUMMARY

CFRD is the most common comorbidity in the CF population and is associated with microvascular complications and protein catabolism leading to worse health outcomes. Recognition of glycemic abnormalities through aggressive screening has led to improvements in nutritional status, pulmonary function, and mortality rates.