Diabetes is associated with dramatically decreased survival in female but not male subjects with cystic fibrosis

Mediation of the total effect of cystic fibrosis-related diabetes on mortality: A UK Cystic Fibrosis Registry cohort study

AIM

To investigate whether the effect of cystic fibrosis-related diabetes (CFRD) on the composite outcome of mortality or transplant could act through lung function, pulmonary exacerbations and/or nutritional status.

METHODS

A retrospective cohort of adult cystic fibrosis (CF) patients who had not been diagnosed with CFRD were identified from the UK Cystic Fibrosis Registry (n = 2750). Rate of death or transplant was compared between patients who did and did not develop CFRD (with insulin use) during follow-up using Poisson regression, separately by sex. Causal mediation methods were used to investigate whether lung function, pulmonary exacerbations and nutritional status lie on the causal pathway between insulin-treated CFRD and mortality/transplant.

RESULTS

At all ages, the mortality/transplant rate was higher in both men and women diagnosed with CFRD. Pulmonary exacerbations were the strongest mediator of the effect of CFRD on mortality/transplant, with an estimated 15% [95% CI: 7%, 28%] of the effect at 2 years post-CFRD diagnosis attributed to exacerbations, growing to 24% [95% CI: 9%, 46%] at 4 years post-diagnosis. Neither lung function nor nutritional status were found to be significant mediators of this effect. Estimates were similar but with wider confidence intervals in a cohort that additionally included people with CFRD but not using insulin.

CONCLUSION

There is evidence that pulmonary exacerbations mediate the effect of CFRD on mortality but, as they are estimated to mediate less than one-quarter of the total effect, the mechanism through which CFRD influences survival may involve other factors.

CGM patterns in adults with cystic fibrosis-related diabetes before and after elexacaftor-tezacaftor-ivacaftor therapy

Cystic fibrosis-related diabetes (CFRD) is a common complication of cystic fibrosis that is associated with worse outcomes and higher mortality rates. CF transmembrane conductance regulator gene (CFTR) modulators have shown favorable effects on lung function, pulmonary exacerbations, and nutrition status. However, data regarding effects of CFTR modulators on glycemic control among those with CFRD is lacking. In this retrospective study, CGM data was analyzed to determine effect of elexacaftortezacaftor- ivacaftor therapy (ETI), a CFTR modulator, on glucose control among patients with CFRD. No difference was seen in glucose patterns after 3- and 6- months of starting ETI.

Methods of analysis for survival outcomes with time-updated mediators, with application to longitudinal disease registry data

Mediation analysis is a useful tool to illuminate the mechanisms through which an exposure affects an outcome but statistical challenges exist with time-to-event outcomes and longitudinal observational data. Natural direct and indirect effects cannot be identified when there are exposure-induced confounders of the mediator-outcome relationship. Previous measurements of a repeatedly-measured mediator may themselves confound the relationship between the mediator and the outcome. To overcome these obstacles, two recent methods have been proposed, one based on path-specific effects and one based on an additive hazards model and the concept of exposure splitting. We investigate these techniques, focusing on their application to observational datasets. We apply both methods to an analysis of the UK Cystic Fibrosis Registry dataset to identify how much of the relationship between onset of cystic fibrosis-related diabetes and subsequent survival acts through pulmonary function. Statistical properties of the methods are investigated using simulation. Both methods produce unbiased estimates of indirect and direct effects in scenarios consistent with their stated assumptions but, if the data are measured infrequently, estimates may be biased. Findings are used to highlight considerations in the interpretation of the observational data analysis.

Just breathe: a review of sex and gender in chronic lung disease

Chronic lung diseases are the third leading cause of death worldwide and are increasing in prevalence over time. Although much of our traditional understanding of health and disease is derived from study of the male of the species - be it animal or human - there is increasing evidence that sex and gender contribute to differences in disease risk, prevalence, presentation, severity, treatment approach, response and outcomes. Chronic obstructive pulmonary disease, asthma and bronchiectasis represent the most prevalent and studied chronic lung diseases and have key sex- and gender-based differences which are critical to consider and incorporate into clinical and research approaches. Mechanistic differences present opportunities for therapeutic development whereas behavioural and clinical differences on the part of patients and providers present opportunities for greater education and understanding at multiple levels. In this review, we seek to summarise the sex- and gender-based differences in key chronic lung diseases and outline the clinical and research implications for stakeholders.

Gestational and pregestational diabetes in pregnant women with cystic fibrosis

As cystic fibrosis transmembrane regulator (CFTR) modulator therapies offer greater longevity and improved health quality, women living with cystic fibrosis (CF) are increasingly pursuing pregnancy. Maternal risks for pregnant women with CF largely depend on a woman's baseline pulmonary and pancreatic function, and the majority of CF pregnancies will successfully end in live births. Diabetes, either gestational or pre-existing cystic fibrosis-related diabetes (CFRD), is highly prevalent in women with CF, affecting 18 to 62% of pregnancies in recent CF center reports. In addition to the rising incidence of CFRD with age, gestational diabetes is also more common in women with CF due to lower insulin secretion, higher insulin resistance, and increased hepatic glucose production as compared to pregnant women without CF. Diabetes occurring during pregnancy has important implications for maternal and fetal health. It is well established in women without CF that glycemic control is directly associated with risks of fetal malformation, neonatal-perinatal mortality, cesarean delivery and need for neonatal intensive care. Small studies in women with CF suggest that pregnancies affected by diabetes have an increased risk of preterm delivery, lower gestational age, and lower fetal birth weight compared to those without diabetes. Women with CF preparing for pregnancy should be counseled on the risks of diabetes and should undergo routine screening for CFRD with oral glucose tolerance testing (OGTT) if not already completed in the past six months. Glycemic control in those with pre-gestational CFRD should be optimized prior to conception. Insulin is preferred for the management of diabetes in pregnant women with CF via multiple daily injections or insulin pump therapy, and continuous glucose monitors (CGM) can be useful in mitigating hypoglycemia risks. Women with CF face many unique challenges impacting diabetes care during pregnancy and would benefit from support by a multidisciplinary care team, including nutrition and endocrinology, to ensure healthy pregnancies.

Cystic fibrosis related diabetes (CFRD) prognosis

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Poor nutritional status and decreased lean body mass.

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Decline in pulmonary function.

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Increased mortality from lung disease.

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Microvascular complications.

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Macrovascular complications (not currently a significant complication but this may change with modulators).

Cystic fibrosis related diabetes (CFRD) occurs in at least 40–50% of adults with CF. With other forms of diabetes, microvascular and macrovascular disease are the major causes of morbidity and mortality. Macrovascular disease is rare in CF. While microvascular disease does occur in this population, there are CF-specific diabetes complications that have a more important impact on prognosis. The additional diagnosis of diabetes in CF is associated with decreased lung function, poor nutritional status, and an overall increase in mortality from lung disease. These negative findings start even before the clinical diagnosis of CFRD, during the period when patients experience abnormal glucose tolerance related to insulin insufficiency. The main mechanisms by which CFRD negatively affects prognosis are thought to be a combination of 1) protein catabolism, decreased lean body mass and undernutrition resulting from insulin insufficiency, and 2) an increased pro-inflammatory and pro-infectious state related to intermittent hyperglycemia. With the introduction of CFTR modulators, the care of CF patients has been revolutionized and many aspects of CF health such as BMI and lung function are improving. The impact of these drugs on the adverse prognosis related to the diagnosis of diabetes in CF, as well as the potential to delay or prevent onset of CFRD remain to be determined.

Impact of Socioeconomic Position on Access to the U.S. Lung Transplant Waiting List in a Matched Cystic Fibrosis Cohort

Rationale: Referrals for lung transplant and transplant rates in the United States are lower than in Canada for patients with advanced cystic fibrosis (CF) lung disease. Further study of factors limiting access are needed to optimize referral and transplant for this population.Objectives: To determine the effect of socioeconomic position, while accounting for disease severity, on the likelihood of wait-listing for lung transplant in the United States.Methods: A case-control study of 3,110 patients (1,555 wait-listed, 1,555 never wait-listed) in the linked CF Foundation Patient Registry/Scientific Registry of Transplant Recipients was performed with 1:1 matching for age, forced expiratory volume in 1 second, and year. Logistic regression was performed with univariate and multivariate analyses accounting for eight clinical factors (sex, oxygen use, body mass index, hemoptysis, forced vital capacity, methicillin-resistant Staphylococcus aureus, multidrug-resistant Pseudomonas aeruginosa, and i.v. antibiotic days) and six socioeconomic factors (race, marital status, education, health insurance, median zip code income, and distance to transplant program). The CF Health Score and Socioeconomic Barrier Score were created based on summation of variables. Interactions between scores were calculated.Results: We found an inverse relationship between the probability of wait-listing and CF Health Score and Socioeconomic Barrier Score. As the CF Health Score decreased (less healthy), the probability of wait-listing increased by 69.3% from a score of 7 to 2. As the Socioeconomic Barrier Score decreased (fewer barriers), the probability of wait-listing increased by 31.7% from a score of ≥5 to 1). Regardless of illness severity, socioeconomic barriers presented an impediment to wait-listing. Individuals with higher Socioeconomic Barrier Scores accessed transplant about half as often as those with lower scores at the same level of medical severity. Analysis of interactions demonstrated a higher probability of wait-listing for individuals with moderate health severity and fewer social barriers compared with sicker individuals with more socioeconomic barriers.Conclusions: Accrual of socioeconomic barriers limits access to lung transplant irrespective of disease severity, a finding of substantial concern for patients with CF and for transplant providers. Future interventions can focus on this at-risk population early in the disease course.

The associations between pediatric weight status and cystic fibrosis-related diabetes status and health-related quality of life among children and young adults with cystic fibrosis: A systematic review

BACKGROUND

Cystic fibrosis (CF) is a life-shortening genetic disease, yet life expectancy has recently increased, shifting the focus to disease management and health-related quality of life (HRQoL). Identification of clinical factors, such as weight status and CF-related diabetes (CFRD), that are associated with HRQoL can inform clinicians about the patient's health perception. The goal of this systematic review was two prong: identify the association of pediatric weight status and HRQoL and determine how CFRD status impacts HRQoL.

METHODS

A systematic review of published research was conducted following the methodology in the Cochrane Handbook on Systematic Reviews for Interventional Studies. Results were reported according to the Preferred Reporting Items for Systematic Review and Meta-Analyses. Risk of bias was assessed using the National Heart Lung & Blood Institute tool. A meta-analysis was not performed due to variability of the inclusion/exclusion criteria, differences in outcome reporting, and insufficient primary outcome data to pool.

RESULTS

Nine studies met inclusion criteria (n = 6 explored weight status and n = 3 studied CFRD), for a total of 1585 subjects (CFRD cases = 87). Pediatric weight status was positively associated with HRQoL, most commonly the Body Image and Eating Disturbance domains. CFRD was negatively associated with HRQoL, specifically the Treatment Burden and Weight domains.

CONCLUSIONS

Based on the limited data available, improved pediatric weight status appears to increase HRQoL while a CFRD diagnosis appears to decrease HRQoL. More research is needed to fully understand the role of these clinical factors on HRQoL, especially with life expectancy increasing among those with CF.

Mechanisms of Post-Pancreatitis Diabetes Mellitus and Cystic Fibrosis-Related Diabetes: A Review of Preclinical Studies

Anatomical proximity and functional correlations between the exocrine and endocrine pancreas warrant reciprocal effects between the two parts. Inflammatory diseases of the exocrine pancreas, such as acute or chronic pancreatitis, or the presence of cystic fibrosis disrupt endocrine function, resulting in diabetes of the exocrine pancreas. Although novel mechanisms are being increasingly identified, the intra- and intercellular pathways regulating exocrine-endocrine interactions are still not fully understood, making the development of new and more effective therapies difficult. Therefore, this review sought to accumulate current knowledge regarding the pathogenesis of diabetes in acute and chronic pancreatitis, as well as cystic fibrosis.

Drug treatments for managing cystic fibrosis-related diabetes

BACKGROUND

The Cystic Fibrosis Foundation recommends both short-term and long-acting insulin therapy when cystic fibrosis-related diabetes (CFRD) has been diagnosed. Diagnosis is based on: an elevated fasting blood glucose level greater than 6.94 mmol/L (125 mg/dL); or oral glucose tolerance tests greater than 11.11 mmol/L (200 mg/dL) at two hours; or symptomatic diabetes for random glucose levels greater than 11.11 mmol/L (200 mg/dL); or glycated hemoglobin levels of at least 6.5%. This is an update of a previously published review.

OBJECTIVES

To establish the effectiveness of insulin and oral agents for managing diabetes in people with cystic fibrosis in relation to blood sugar levels, lung function and weight management.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. We also handsearched abstracts from pulmonary symposia and the North American Cystic Fibrosis Conferences. Date of most recent register search: 10 September 2020. We searched online trials registries; date of most recent searches: 21 March 2020.

SELECTION CRITERIA

Randomized controlled trials comparing all methods of pharmacological diabetes therapy in people with diagnosed CFRD.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed the risk of bias in the included studies. Authors also used GRADE to assess the quality of the evidence.

MAIN RESULTS

The searches identified 29 trials (45 references). Four included trials provide results: one short-term single-center cross-over trial (seven adults) comparing insulin with oral repaglinide and no medication in adults with CFRD and normal fasting glucose; one long-term multicenter trial (61 adults with CFRD) comparing insulin with oral repaglinide and placebo; one long-term multicenter trial (67 adults) comparing insulin with oral repaglinide; and one 12-week single-center cross-over trial (20 adults) comparing the long-acting insulin glargine to short-term neutral protamine Hagedorn insulin. Two ongoing trials of newly approved incretin mimics have been noted for possible future inclusion. Downgrading of the quality of the evidence was mainly due to risks of bias across all domains, but particularly due to concerns surrounding allocation concealment and selective reporting. There were also some concerns due to imprecision from small sample sizes and low event rates. Finally, there may be some bias due to the amounts of insulin and repaglinide given not being comparable. Data from one trial comparing insulin to placebo (39 participants) did not show any difference between groups for the primary outcomes of blood glucose levels (very low-quality evidence), lung function (low-quality evidence) or nutritional status (low-quality evidence). Similarly, no differences between groups were seen for the secondary outcomes of number of hypoglycemic episodes (low-quality evidence), secondary infection complications or quality of life (QoL). These results were mirrored in the narrative reports for the second trial in this comparison (seven participants). Data from the one-year trial comparing repaglinide to placebo (38 participants), showed no differences between groups for the primary outcomes of blood glucose levels (very low-quality evidence), lung function (low-quality evidence) and nutritional status (low-quality evidence). Also, no differences were seen between groups for the secondary outcomes of number of hypoglycemic episodes (low-quality evidence), secondary infection complications or QoL. These findings were mirrored in the narrative reports for the second trial (n = 7) in this comparison. Three trials compared insulin to repaglinide (119 participants). Data from one trial (n = 67) showed no difference in blood glucose levels at either 12 months (high-quality evidence) or 24 months; narrative reports from one trial (45 participants) reported no difference between groups, but the second trial (7 participants) reported a beneficial effect of insulin over repaglinide. Two trials (112 participants) found no difference between insulin and repaglinide in lung function or nutritional status (moderate-quality evidence). Two trials (56 participants) reported no difference in the number of hypoglycemic episodes (low-quality evidence). One trial (45 participants) reported no difference between groups in secondary infections and cystic fibrosis QoL. The single trial comparing glargine to neutral protamine Hagedorn insulin did not report directly on the review's primary outcomes, but did report no differences between groups in post-prandial glucose values and weight; neither group reported infectious complications. There was no difference in episodes of hypoglycemia (very low-quality evidence) and while there was no difference reported in QoL, all participants opted to continue treatment with glargine after the trial was completed. Mortality was not reported by any trial in any comparison, but death was not given as a reason for withdrawal in any trial.

AUTHORS' CONCLUSIONS

This review has not found any conclusive evidence that any agent has a distinct advantage over another in controlling hyperglycemia or the clinical outcomes associated with CFRD. Given the treatment burden already experienced by people with cystic fibrosis, oral therapy may be a viable treatment option. While some cystic fibrosis centers use oral medications to help control diabetes, the Cystic Fibrosis Foundation (USA) clinical practice guidelines support the use of insulin therapy and this remains the most widely-used treatment method. Randomized controlled trials specifically related to controlling diabetes and its impact on the course of pulmonary disease process in cystic fibrosis continue to be a high priority. Specifically, investigators should evaluate adherence to different therapies and also whether there is benefit in using additional hypoglycemic agents as well as the newly approved incretin mimics. Agents that potentiate insulin action, especially agents with additional anti-inflammatory potential should also be further investigated as adjuvant therapy to insulin.

Bidirectional relationship between diabetes and pulmonary function: a systematic review and meta-analysis

AIM

Evidence of the lungs being a target organ of diabetes-related pathophysiology is increasing, and decreased pulmonary function increases the risk of diabetes after adjusting for demographic and metabolic factors. This systematic review and meta-analysis evaluates the bidirectional relationship between diabetes and pulmonary function.

METHODS

MEDLINE, Embase, The Cochrane Library and Web of Science databases were searched, and all studies describing this bidirectional relationship were identified. Two reviewers independently extracted study characteristics and assessed the risk of bias.

RESULTS

A total of 93 studies were included in the meta-analysis. The pooled weighted mean difference (WMD) between diabetes patients and non-diabetic participants for forced expiratory volume in 1 s (FEV₁) and forced vital capacity (FVC) were -5.65% and -5.91%, respectively, of predicted values. Diabetes-related microvascular complications and poor glycaemic control were associated with poorer pulmonary function in those with diabetes. In addition, diabetes was associated with a restrictive spirometry pattern (RSP) in both cross-sectional studies [odds ratio (OR): 2.88, 95% confidence interval (CI): 2.18-3.81, I² = 0.0%] and prospective cohort studies [hazard ratio (HR): 1.57, 95% CI: 1.04-2.36]. In five longitudinal studies, the conclusions were inconsistent as to whether or not diabetes accelerates pulmonary function decline. However, every 10% decrease in baseline predicted FVC value was associated with a 13% higher risk of incident diabetes (HR: 1.13, 95% CI: 1.09-1.17, I² = 0.0%).

CONCLUSION

There is a bidirectional relationship between diabetes and pulmonary function. However, further investigations into whether dynamic changes in glycaemic levels before and shortly after diabetes onset mediate the deleterious effects on pulmonary function, or vice versa, are now required.

Cystic Fibrosis Related Diabetes - An Update

Cystic fibrosis (CF) is the most common life-threatening inherited condition in the Caucasian population, where mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene result in a multifactorial syndrome, with pulmonary disease representing the largest contributor to morbidity and mortality. Life expectancy has improved and the recent development of disease-modifying CFTR modulator therapies is likely to further improve survival. However, increasing life expectancy brings new challenges related to the complications of a chronic disease including an increasing prevalence of cystic fibrosis related diabetes (CFRD), itself associated with increased morbidity and early mortality. This review provides an update as regards the underlying mechanisms, investigation and management of CFRD.

Applications and pitfalls of hemoglobin A1C and alternative methods of glycemic monitoring

INTRODUCTION

Intensive glycemic control minimizes the risks of microvascular complications in diabetes. A1C is a convenient estimate of mean blood glucose, but is not the only marker available. The practical use and limitations of alternative markers and continuous glucose monitors are the focus of this review.

METHODS

PubMed and the Cochrane Library were searched for studies concerning applications or limitations of A1C, fructosamine, glycated albumin, 1,5-anhydroglucitol, skin autofluorescence, and continuous glucose monitoring. Papers reporting on strengths, limitations, or comparisons of these methods were reviewed for inclusion.

RESULTS

A1C reflects three months of glycemic control and is not an ideal marker in all patient populations. Fructosamine and glycated albumin reflect mean blood glucose over three weeks. 1,5-Anhydroglucitol can measure hyperglycemic excursions in days to weeks. Continuous glucose monitors provide immediate feedback for timely intervention to reduce glycemic excursions and can assess glycemic variability. Current barriers to continuous glucose monitor use include inexperience, cost, discomfort, and medication interference.

CONCLUSIONS

Many promising alternative glycemic markers exist. The main limitations for all alternative methods of glycemic monitoring are a lack of standardization for clinically useful cut-offs or guidelines, and a lack of long-term data on their association with complications, particularly in varied patient populations.

Retinopathy and microalbuminuria are common microvascular complications in cystic fibrosis-related diabetes

AIMS

To study the prevalence of microvascular complications and renal changes associated with cystic fibrosis-related diabetes (CFRD).

METHODS

This retrospective cohort study was conducted at the West Midlands Adult Cystic Fibrosis centre, United Kingdom. Data regarding age, sex, microalbuminuria, retinopathy neuropathy, and biochemical results were collected for all people with CFRD who had an annual review from 1 January 2018 to 31 December 2018 at the centre. Descriptive statistics were analysed using STATAv15.1.

RESULTS

A total of 189 patients were included, of which 56.6% were male and median age (interquartile range) was 33 (27-39) years; 79.4% (150/189) had their annual review in 2018. Those with a biochemically impaired renal function numbered 7.2% (13/180) and 22.7% (32/141) had microalbuminuria; 17.2% (10/58) had diabetes related retinopathy. No one in our cohort had diabetic ulcers; however, 10.3% (13/126) had absent foot pulses.

CONCLUSION

We found a higher prevalence of microalbuminuria compared with retinopathy in a large cohort of cystic fibrosis adults. This study demonstrates the need for regular specialist follow-up to facilitate early identification of such complications and a long-term prospective cohort to understand underlying mechanisms.

Carbohydrate counting accuracy in adults with cystic fibrosis related diabetes

AIM

Poorly controlled Cystic Fibrosis-Related Diabetes (CFRD) is associated with adverse impacts on lung function and nutritional status. Insulin therapy is the only recommended medical treatment. Carbohydrate Counting (CC) is used to guide insulin doses and can assist in achieving optimal postprandial blood glucose levels. This study aimed to determine the prevalence of individuals with CFRD who carbohydrate count, explore barriers to its use and assess the accuracy of CC in hospitalised patients.

METHODS

A cross-sectional, mixed-methods, descriptive study recruited individuals with CFRD hospitalised at an Australian tertiary hospital. Consenting patients completed a questionnaire. Patients were asked to estimate the carbohydrate content of their ordered meals provided by hospital foodservices. The study dietitian assessed each meal's estimation against the actual content.

RESULTS

17 individuals were recruited to this study and five declined. Seven had a fixed insulin regimen, and ten had a flexible insulin regimen and used CC. Patients in the fixed insulin group reported lower levels of confidence in their ability to carbohydrate count (P < .001) and placed less importance on CC (P < .001). 53% of the fixed insulin group's and 41.7% of the flexible insulin group's estimations of the carbohydrate content of the hospital food items were accurate.

CONCLUSION

Of those patients recruited to this study, 59% used CC as a tool to guide insulin dosing, and patients estimated accurate carbohydrate values in only 46% of meals. Further research is warranted to investigate the most suitable method to assist accurate carbohydrate content estimations in a hospital setting.

Screening for cystic fibrosis-related diabetes and prediabetes: Evaluating 1,5-anhydroglucitol, fructosamine, glycated albumin, and hemoglobin A1c

OBJECTIVE

Dysglycemia is prevalent in cystic fibrosis (CF) but screening with annual oral glucose tolerance tests (OGTT) can be burdensome. We investigated alternate glycemic markers-hemoglobin A1c (HbA1c), 1,5-anhydroglucitol (1,5AG), fructosamine (FA), and glycated albumin (GA)-as screening tests for CF-related diabetes (CFRD) and pre-diabetes (CFPD) in youth with CF as defined by the gold-standard OGTT 2-hour glucose (2hG).

METHODS

Youth 10 to 18 years with CF had a 1,5AG, FA, GA, HbA1c, and 2-hour OGTT collected. Correlations between all glycemic markers and 2hG were evaluated. Area under the receiver operative characteristic (ROC-AUC) curves were generated. Optimal cut points for predicting CFPD (2hG ≥ 140 mg/dL) and CFRD (2hG ≥ 200 mg/dL) were determined.

RESULTS

Fifty-eight youth with CF were included (2hG < 140, n = 16; CFPD, n = 33; CFRD, n = 9; 41% male, mean ± SD age 14.2 ± 3.6 years, BMI z-score 0.0 ± 0.8, % predicted forced expiratory volume in 1 second [FEV1] 89.9 ± 15.1, % predicted forced vital capacity [FVC] 103.2 ± 14.6). ROC-AUC's for all alternate markers were low for CFPD (0.52-0.67) and CFRD (0.56-0.61). At a cut point of 5.5%, HbA1c had 78% sensitivity (95% CI: 0.45-0.94) and 41% specificity (95% CI: 0.28-0.55) for identifying CFRD, correlating to a ROC-AUC of 0.61 (95% CI: 0.42-0.8).

CONCLUSIONS

All alternate markers tested demonstrate poor diagnostic accuracy for identifying CFRD by 2hG.

The demographics of adverse outcomes in cystic fibrosis

Understanding variability in cystic fibrosis (CF) health outcomes requires an understanding of factors that go far beyond Cystic Fibrosis Transmembrane Receptor (CFTR) function caused by different gene mutations. Social and environmental factors that influence health have a significant influence on the trajectory of health in CF and in other chronic diseases. In this article, we review demographic factors associated with poorer health outcomes in CF, known and postulated biological mechanisms of these outcomes, and interventions that healthcare teams can implement that may reduce outcome disparities.

Cystic fibrosis related diabetes in Europe: Prevalence, risk factors and outcome; Olesen et al

BACKGROUND

Cystic fibrosis related diabetes (CFRD) has implications for morbidity and mortality with several risk factors identified. We studied the epidemiology of CFRD in the large dataset of the European Cystic Fibrosis Society Patient registry.

METHODS

Data on CF patients were investigated for the prevalence of CFRD as well as for any association with suggested risk factors and effects.

RESULTS

CFRD increased by approximately ten percentage points every decade from ten years of age. Prevalence was higher in females in the younger age groups. CFRD was associated with severe CF genotypes (OR = 3.11, 95%CI: 2.77-3.48), pancreatic insufficiency (OR = 1.46, 95%CI: 1.39-1.53) and female gender (OR = 1.28, 95%CI: 1.21-1.34). Patients with CFRD had higher odds of being chronically infected with Pseudomonas aeruginosa, Burkholderia cepacia complex and Stenotrophomonas maltophilia than patients without CFRD, higher odds of having FEV1% of predicted <40% (OR = 1.82, 95%CI: 1.70-1.94) and higher odds of having BMI SDS ≤-2 than patients without CFRD (OR = 1.24, 95%CI: 1.15-1.34).

CONCLUSIONS

Severe genotype, pancreatic insufficiency and female gender remain considerable intrinsic risk factors for early acquisition of CFRD. CFRD is associated with infections, lower lung function and poor nutritional status. Early diagnosis and aggressive treatment of CFRD are more important than ever with increasing life span.

[Other specific types of diabetes and exocrine pancreatic insufficiency (Update 2019)]

The heterogenous catagory "specific types of diabetes due to other causes" encompasses disturbances in glucose metabolism due to other endocrine disorders such as acromegaly or hypercortisolism, drug-induced diabetes (e. g. antipsychotic medications, glucocorticoids, immunosuppressive agents, highly active antiretroviral therapy (HAART)), genetic forms of diabetes (e. g. Maturity Onset Diabetes of the Young (MODY), neonatal diabetes, Down Syndrome, Klinefelter Syndrome, Turner Syndrome), pancreatogenic diabetes (e. g. postoperatively, pancreatitis, pancreatic cancer, haemochromatosis, cystic fibrosis), and some rare autoimmune or infectious forms of diabetes. Diagnosis of specific diabetes types might influence therapeutic considerations. Exocrine pancreatic insufficiency is not only found in patients with pancreatogenic diabetes but is also frequently seen in type 1 and long-standing type 2 diabetes.

MARKEDLY DELAYED INSULIN SECRETION AND A HIGH RATE OF UNDETECTED OVERT DIABETES CHARACTERIZE GLUCOSE METABOLISM IN ADULT PATIENTS WITH CYSTIC FIBROSIS AFTER LUNG TRANSPLANTATION

OBJECTIVE

Cystic fibrosis-related diabetes (CFRD) is associated with adverse clinical outcomes and should be screened for by an annual oral glucose tolerance test (OGTT). Since pathophysiologic studies have mainly been performed in a pediatric/adolescent, nontransplanted collective, we aimed to assess parameters of insulin secretion and sensitivity in adult cystic fibrosis (CF) patients after lung transplantation (LT).

METHODS

Twelve adult CF patients after LT without known diabetes (33.3 ± 11.5 years; body mass index [BMI] 21.5 ± 3.3 kg/m²) and 8 control subjects matched by age (36.0 ± 6.6 years; P>.05), BMI (22.3 ± 1.5 kg/m²; P>.05), and gender (CON group) underwent a 3-hour OGTT with glucose, insulin, and C-peptide measurements. Parameters of insulin secretion and sensitivity as well as lipid profiles were assessed.

RESULTS

In the CF group, 4 patients were diagnosed with overt diabetes (CFRD) compared to CF patients without diabetes (CF-noDM), of whom 6 had indeterminate glycemia with 1-h glucose values >200 mg/dL. The insulin peak after glucose load occurred after 30 minutes in CON, after 90 minutes in CF-noDM, and was missing in CFRD. Insulin sensitivity was comparable between the groups. Beta-cell glucose sensitivity was markedly reduced in CFRD (10.7 ± 5.8 pmol/min*m²*mM), higher in CF-noDM (39.9 ± 23.4 pmol/min*m²*mM), but still significantly lower compared to CON (108.3 ± 53.9 pmol/min*m²*mM; P = .0008). CFRD patients exhibited increased triglyceride levels and decreased high-density lipoprotein levels.

CONCLUSION

Adult CF patients after LT have profound disturbances in glucose metabolism, with a high rate of undetected diabetes and markedly delayed insulin secretion. Curbed beta-cell glucose sensitivity rather than insulin resistance explains postprandial hyperglycemia and is accompanied by abnormalities in lipid metabolism.

ABBREVIATIONS

AUC = area under the curve; BMI = body mass index; CF = cystic fibrosis; CFRD = cystic fibrosis-related diabetes; CFTR = cystic fibrosis transmembrane-conductance regulator; CF-TX = cystic fibrosis patients who underwent lung transplantation; CGM = continuous glucose monitoring; HbA1c = glycated hemoglobin; HDL = high-density lipoprotein; INDET = indeterminate glycemia; LDL = low-density lipoprotein; LT = lung transplantation; OGIS = oral glucose sensitivity index; OGTT = oral glucose tolerance test; QUICKI = quantitative insulin sensitivity check index.

The Salt without the Girl: Negotiating Embodied Identity as an Agender Person with Cystic Fibrosis

In this manuscript, I build and expand on prior work by myself (Nowakowski, 2016) and others exploring the dynamics of embodiment among people with chronic health conditions. Specifically, I critically investigate the intersecting social and medical elements of responses to bodies perceived as too thin and otherwise lacking in physical ability, using my own experiences of living and aging with cystic fibrosis (CF) as a case example. In these explorations, I center gendered identity and its intersection with disabling physical illness. I do so by using my own lived experiences as autoethnographic anchor points to guide critical review of key concepts from the nexus of these two content areas. I focus throughout on exploring how others’ reactions to a frail-looking body often constitute a form of forced gendering via the narratives people attempt to construct for why a person’s body appears that way. The title of the manuscript supports this framework by referencing three cornerstones of patient experience in the CF community: the general trend of patients having salty skin due to the pathology of the disease, a prior embodiment project called Salty Girls (Pettigrew, 2012) that engages this idea, and the more abstract concept of “saltiness” in describing the grit marginalized people display in responding to microaggressions.

Diabetes of the exocrine pancreas

Diabetes of the exocrine pancreas (DEP) is a form of diabetes that occurs due to pancreatic disease. It is far more common than has been previously considered, with a recent study showing 1.8% of adults with new-onset diabetes should have been classified as DEP. The majority is misdiagnosed as type 2 diabetes mellitus (T2DM). Patients with DEP exhibit varying degrees of exocrine and endocrine dysfunction. Damage to the islet of Langerhans effects the secretion of hormones from the β, α, and pancreatic polypeptide cells; the combination of low insulin, glucagon, and pancreatic polypeptide contributes to rapid fluctuations in glucose levels. This form of "brittle diabetes" may result in the poorer glycemic control observed in patients with DEP, when compared with those with T2DM. Diabetes of the exocrine pancreas has a different natural history to other forms of diabetes; patients are more likely to require early insulin initiation compared with those with T2DM. Therefore, individuals with DEP should be advised about the symptoms of decompensated hyperglycemia, although they are less likely to develop ketoacidosis. Clinicians should screen for DEP in patients with acute or chronic pancreatitis, following pancreatic resection, or with co-existing cystic fibrosis or hemochromatosis. Incident diabetes may herald the onset of pancreatic ductal carcinoma in a small subset of patients. Once identified, patients with DEP can benefit from specific lifestyle advice, pancreatic enzyme replacement therapy, metformin treatment, appropriate insulin dosing, and monitoring. Further research is needed to establish the ideal treatment regimens to provide optimal clinical outcomes for this unique form of diabetes.

Continuous glucose monitoring in youth with cystic fibrosis treated with lumacaftor-ivacaftor

BACKGROUND

The effects of lumacaftor-ivacaftor therapy on glycemia have not been thoroughly investigated. Continuous glucose monitoring (CGM) provides detailed information about glycemic patterns and detects glucose abnormalities earlier than traditional screening tools for diabetes.

METHODS

CGM measures, HbA1c, and oral glucose tolerance test (OGTT) results were collected and within-subject results compared in F508del homozygous youth with CF before and after initiation of lumacaftor-ivacaftor using the Wilcoxon signed-rank test.

RESULTS

Nine youth with CF (6 males, median age 12.7 years) were enrolled. CGM was performed in all participants before (median 26 weeks) and after lumacaftor-ivacaftor (median 29 weeks). HbA1c and fasting plasma glucose increased (p = .02) after lumacaftor-ivacaftor initiation. No changes in OGTT 1 h or 2 h glucose nor CGM measures were observed overall. When analyzed by sex, males showed lower glycemic variability, as reflected by the mean amplitude of glycemic excursions, on the post-treatment CGM.

CONCLUSIONS

Glycemic abnormalities persisted in CF patients treated with lumacaftor-ivacaftor, although sex-dependent differences in glycemic response to treatment may exist.

Unique challenges of cystic fibrosis-related diabetes

Individuals with cystic fibrosis and pancreatic insufficiency have a gradual decline in insulin secretion over time, which results in an increase in the prevalence of diabetes with age; up to 50% of adults with cystic fibrosis aged over 35 years have diabetes. Cystic fibrosis-related diabetes differs from Type 1 and Type 2 diabetes in several ways; there is a pattern of insulin deficiency with reduced and delayed insulin response to carbohydrates but a sparing of basal insulin that results in glucose abnormalities, which are frequently characterized by normal fasting glucose and postprandial hyperglycaemia. Insulin deficiency and hyperglycaemia, even at levels which do not reach the threshold for a diagnosis of diabetes, have an adverse impact on lung function and clinical status in people with cystic fibrosis. Although the risk of microvascular complications occurs as in other forms of diabetes, the main reason for treatment is to prevent deterioration in lung function and weight loss; treatment may therefore be required at an earlier stage than for other types of diabetes. Treatment is usually with insulin, but management needs to take into account all the other medical issues that arise in cystic fibrosis.

Cystic Fibrosis-Related Diabetes

Cystic fibrosis (CF) is the most common autosomal recessive disorder in Caucasian populations. Individuals with CF have seen significant increases in life expectancy in the last 60 years. As a result, previously rare complications are now coming to light. The most common of these is cystic fibrosis-related diabetes (CFRD), which affects 40-50% of CF adults. CFRD significantly impacts the pulmonary function and longevity of CF patients, yet a lack of consensus on the best methods to diagnose and treat CFRD remains. We begin by reviewing our understanding of the pathogenesis of CFRD, as emerging evidence shows the cystic fibrosis transmembrane conductance regulator (CFTR) also has important roles in the release of insulin and glucagon and in the protection of β cells from oxidative stress. We then discuss how current recommended methods of CFRD diagnosis are not appropriate, as continuous glucose monitoring becomes more effective, practical, and cost-effective. Finally, we evaluate emerging treatments which have narrowed the mortality gap within the CF patient group. In the future, pharmacological potentiators and correctors directly targeting CFTR show huge promise for both CFRD and the wider CF patient groups.

An update on new and emerging therapies for cystic fibrosis

INTRODUCTION

Cystic fibrosis (CF) is a genetic disorder that results in a multi-organ disease with progressive respiratory decline that ultimately leads to premature death. CF is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which codes for the CFTR anion channel. Established CF treatments target downstream manifestations of the primary genetic defect, including pulmonary and nutritional interventions. Areas covered: CFTR modulators are novel therapies that improve the function of CFTR, and have been approved in the past five years to mitigate the effects of several CF-disease causing mutations. This review summarizes currently approved CFTR modulators and discusses emerging modulator therapies in phase II and III clinical trials described on clinical trials.gov as of April, 2017. Results of relevant trials reported in peer-reviewed journals in Pubmed, scientific conference abstracts and sponsor press releases available as of November, 2017 are included. Expert opinion: The current scope of CF therapeutic development is robust and CFTR modulators have demonstrated significant benefit to patients with specific CFTR mutations. We anticipate that in the future healthcare providers will be faced with a different treatment paradigm, initiating CFTR-directed therapies well before the onset of progressive lung disease.

Impact of Treatments on Diabetic Control and Gastrointestinal Symptoms After Total Pancreatectomy

OBJECTIVES

The aims of this study were to compare the safety, efficacy, and patients' quality of life with continuous subcutaneous insulin infusion (CSII) versus multiple daily injections (MDIs) in type 3c diabetes mellitus (T3cDM) following total pancreatectomy (TP) and pancreatic enzyme usage.

METHODS

Thirty-nine patients with T3cDM (18 CSII patients vs 21 MDI patients) who underwent TP between 2000 and 2016 at 3 Harvard-affiliated hospitals and the University of Minnesota returned prospectively obtained questionnaires examining quality of life and both endocrine and exocrine pancreatic functions.

RESULTS

Main indications for TP were as follows: chronic pancreatitis (n = 19), intraductal papillary mucinous neoplasm (n = 12), and adenocarcinoma (n = 4). Median hemoglobin A1c using MDIs was 8.1% versus 7.3% in CSII. Severe hypoglycemic events using MDIs were increased compared with CSII (P = 0.02). There were no significant differences in quality-of-life measures with CSII versus MDIs. Pancreatic enzyme dose per meal (P < 0.05) differed between the hospitals. Gastrointestinal symptoms and unintended weight loss (P < 0.01) were more common with low doses of pancreatic enzymes.

CONCLUSIONS

After TP, CSII therapy is safe compared with MDIs in T3cDM and not associated with an increase in severe hypoglycemic events. Pancreatic enzyme replacement therapy is highly variable with low doses associated with unintentional weight loss and gastrointestinal symptoms.

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.

The changing epidemiology and demography of cystic fibrosis

Once considered a pediatric disease with a poor prognosis, individuals born with cystic fibrosis (CF) today can expect to live well into adulthood. The implementation of multidisciplinary care, novel treatments and newborn screening has resulted in the rapid evolution in the demographics of the CF population. The purpose of this review is to highlight the evolving epidemiology and demographics of the CF population internationally.

Risk factors for persistent methicillin-resistant Staphylococcus aureus infection in cystic fibrosis

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as an important pathogen in cystic fibrosis (CF). Over 25% of individuals in the United States with CF are found to have MRSA in respiratory culture specimens, and persistent MRSA infection has been associated with more rapid decline in lung function and increased mortality. The objective of this study was to investigate clinical and demographic characteristics that are associated with the development of persistent MRSA infection in a CF population.

METHODS

This was a retrospective cohort study of individuals followed from 2002 to 2012 in the Cystic Fibrosis Foundation Patient Registry. A time-to-event analysis for the development of persistent MRSA infection was performed, and multivariable Cox proportional hazards models were constructed to identify risk factors for infection.

RESULTS

The study cohort included 19,434 individuals, of which 5844 would develop persistent MRSA infection. In the adjusted model, pancreatic insufficiency (HR: 1.49; 95% CI: 1.29-1.72), CF related diabetes (HR: 1.13; 95% CI: 1.05-1.20), co-infection with P. aeruginosa (HR: 1.21; 95% CI: 1.13-1.28), and number of hospitalizations/year (HR: 1.09; 95% CI: 1.06-1.12) were all associated with increased risk, whereas higher socio-economic status (HR: 0.87; 95% CI: 0.82-0.93) was associated with a lower risk. Receiving care at a CF center with increased MRSA prevalence was associated with increased risk of MRSA infection: highest quartile (HR: 2.33; 95% CI: 2.13-2.56).

CONCLUSIONS

No easily modifiable risk factors for persistent MRSA were identified in this study. However, several risk factors for patients at higher risk for persistent MRSA infection were identified, for example centers with a high baseline MRSA prevalence, and may be useful in designing center-specific MRSA infection prevention and control strategies and/or eradication protocols. Additional studies are needed in order to evaluate if attention to these risk factors can improve clinical outcomes.

Cystic Fibrosis Related Diabetes: a Unique Challenge in Diabetes Care

Cystic Fibrosis (CF) is a common autosomal recessive disease that affects multiple organs due to a defect in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR). This transporter is present in various organs and tissues, including the airway epithelium, sinuses, pancreas, intestine, biliary tree, the vas deferens, and the sweat ducts, making CF a multi-system disease1. As CF patients are living longer, pancreatic function declines and diabetes emerges, further complicating the nutritional status and care of these patients.

The 1-h oral glucose tolerance test glucose and insulin values are associated with markers of clinical deterioration in cystic fibrosis

AIMS

Cystic fibrosis (CF) is associated with the emergence of CF-related diabetes (CFRD). CFRD is associated with increased risk of accelerated weight and/or lung function loss (clinical degradation). Data in the CF pediatric population reported an association between higher 60-min oral glucose tolerance test (OGTT) plasma glucose values and reduced lung function. Our objective was to evaluate the relationship between the 60-min OGTT insulin and glucose values and markers of clinical degradation in adult patients with CF.

METHODS

This study was based on an ongoing observational cohort of CF adult patients (≥18 years). All patients underwent a 2-h OGTT with 30-min interval sample measurements. Plasma insulin and glucose levels were measured. Adult patients (N = 240) were categorized based on the 60-min OGTT median values of glucose (G60, 11.0 mmol/L) and/or insulin (I60, 43.4 μU/mL).

RESULTS

A negative association was observed between the 60-min OGTT glucose value and pulmonary function (FEV1; P = 0.001), whereas 60-min OGTT insulin values were positively associated with BMI (P = 0.004). Patients with high G60 values displayed lower FEV1 than patients with low G60 values (P = 0.025). Patients with higher I60 values demonstrated higher values of both FEV1 (P = 0.022) and BMI (P = 0.003) than patients with low I60 values. More importantly, when adjusting for BMI, the difference in FEV1 between both groups no longer existed (P = 0.166).

CONCLUSIONS

Both insulin and glucose values at 60-min OGTT are associated with indicators of clinical degradation in adult patients with CF. Future prospective analyses are essential in establishing the clinical utility of these indicators.

Insulin and oral agents for managing cystic fibrosis-related diabetes

BACKGROUND

The Cystic Fibrosis Foundation recommends both short-term and long-acting insulin therapy when cystic fibrosis-related diabetes has been diagnosed. Diagnosis is based on: an elevated fasting blood glucose level greater than 6.94 mmol/liter (125 mg/deciliter); or oral glucose tolerance tests greater than 11.11 mmol/liter (200 mg/deciliter) at two hours; or symptomatic diabetes for random glucose levels greater than 11.11 mmol/liter (200 mg/deciliter); or glycated hemoglobin levels of at least 6.5%.

OBJECTIVES

To establish the effectiveness of insulin and oral agents for managing diabetes in people with cystic fibrosis in relation to blood sugar levels, lung function and weight management.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. We also handsearched abstracts from pulmonary symposia and the North American Cystic Fibrosis Conferences.Date of the most recent search of the Group's Cystic Fibrosis Trials Register: 18 February 2016.

SELECTION CRITERIA

Randomized controlled trials comparing all methods of diabetes therapy in people with diagnosed cystic fibrosis-related diabetes.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed the risk of bias in the included studies.

MAIN RESULTS

The searches identified 22 trials (34 references). Four trials (200 participants) are included: one short-term single-center trial (n = 7) comparing insulin with oral repaglinide and no medication in people with cystic fibrosis-related diabetes and normal fasting glucose; one long-term multicenter trial (n = 100, 74 of whom had cystic fibrosis-related diabetes) comparing insulin with oral repaglinide and placebo; one long-term multicenter trial (n = 73) comparing insulin with oral repaglinide; and one 12-week single-center trial (n = 20) comparing the long-acting insulin glargine to short-term neutral protamine Hagedorn insulin.Two trials with data for the comparison of insulin to placebo did not report any significant differences between groups for the primary outcomes of blood glucose levels, lung function and nutritional status. This was also true for the single trial with data for the comparison of repaglinide to placebo. Two trials (one lasting one year and one lasting two years) contributed data for the comparison of insulin versus repaglinide. There were no significant differences for the primary outcomes at any time point, except at one year (in the two-year trial) when the insulin group had significant improvement in z score for body mass index compared to the repaglinide group. The single trial comparing glargine to neutral protamine Hagedorn insulin also did not report any significant differences in the review's primary outcomes. A few cases of hypoglycemia were seen in three out of the four trials (none in the longest trial), but these events resolved without further treatment.There was an unclear risk of bias from randomization and allocation concealment in two of the four included trials as the authors did not report any details; in the remaining two studies details for randomization led to a low risk of bias, but only one had sufficient details on allocation concealment to allow a low risk judgement, the second was unclear. There was a high risk from blinding for all trials (except for the comparison of oral repaglinide versus placebo) due to the nature of the interventions. Complete data for all outcomes were not available from any trial leading to a high risk of reporting bias. The amounts of insulin and repaglinide administered were not comparable and this may lead to bias in the results. None of the included trials were powered to show a significant improvement in lung function.

AUTHORS' CONCLUSIONS

This review has not found any significant conclusive evidence that long-acting insulins, short-acting insulins or oral hypoglycemic agents have a distinct advantage over one another in controlling hyperglycemia or clinical outcomes associated with cystic fibrosis-related diabetes. While some cystic fibrosis centers use oral medications to help control diabetes, the Cystic Fibrosis Foundation (USA) clinical practice guidelines support the use of insulin therapy and this remains the most widely-used treatment method. Randomized controlled trials specifically related to controlling diabetes with this impact on the course of pulmonary disease process in cystic fibrosis continue to be a high priority.There is no demonstrated advantage yet established for using oral hypoglycemic agents over insulin, and further trials need to be evaluated to establish whether there is clear benefit for using hypoglycemic agents. Agents that potentiate insulin action, especially agents with additional anti-inflammatory potential should be further investigated to see if there may be a clinical advantage to adding these medications to insulin as adjuvant therapy.

Assessing Differences in Mortality Rates and Risk Factors Between Hispanic and Non-Hispanic Patients With Cystic Fibrosis in California

BACKGROUND

Over the past 30 years, therapeutic advances have extended the median lifespan of patients with cystic fibrosis (CF). Hispanic patients are a vulnerable subpopulation with a high prevalence of risk factors for worse health outcomes. The consequences of these differences on health outcomes have not been well described. The objective of this study was to characterize the difference in health outcomes, including mortality rate, between Hispanic and non-Hispanic patients with CF.

METHODS

This study is a retrospective analysis of CF Foundation Patient Registry data of California residents with CF, diagnosed during or after 1991, from 1991 to 2010. Ethnicity was self-reported. The primary outcome was mortality. Hazard ratios were estimated from a Cox regression model, stratified by sex, and adjusted for socioeconomic status, clinical risk factors, and year of diagnosis.

RESULTS

Of 1,719 patients, 485 (28.2%) self-identified as Hispanic. Eighty-five deaths occurred, with an overall mortality rate of 4.9%. The unadjusted mortality rate was higher among Hispanic patients than among non-Hispanic patients (9.1% vs 3.3%, P < .0001). Compared with non-Hispanic patients, Hispanic patients had a lower survival rate 18 years after diagnosis (75.9% vs 91.5%, P < .0001). Adjusted for socioeconomic status and clinical risk factors, Hispanic patients had an increased rate of death compared with non-Hispanic patients (hazard ratio, 2.81; 95% CI, 1.70-4.63).

CONCLUSIONS

Hispanic patients with CF have a higher mortality rate than do non-Hispanic patients, even after adjusting for socioeconomic status and clinical severity. Further investigation into the mechanism for the measured difference in lung function will help inform interventions and improve the health of all patients with CF.

Glucose >200 mg/dL during Continuous Glucose Monitoring Identifies Adult Patients at Risk for Development of Cystic Fibrosis Related Diabetes

Rationale. Cystic fibrosis related diabetes (CFRD) is the most common comorbidity in patients with CF. In spite of increased screening, diagnosis, and treatment of CFRD, the mortality rate in patients with CFRD still far exceeds the mortality rate in those without CFRD. Guidelines suggest that screening for CFRD be performed annually using the 2-hour 75-gram oral glucose tolerance test (OGTT). Adherence to recommended screening has been poor, with only approximately one-quarter of adults with CF undergoing OGTT in 2014. Use of continuous glucose monitoring (CGM) for diagnosis may become an alternative. Objectives. Our objective was to determine whether abnormal CGM predicts subsequent development of CFRD, lung function, and body mass index (BMI) decline and increased rate of CF pulmonary exacerbations in adults with CF. Methods. In a prospective single center pilot trial from September 2009 to September 2010, 21 adult patients due for routine OGTT were recruited to complete simultaneous 3-day CGM and 2-hour 75 gram OGTT. Subsequently, clinical information was reviewed from 2008 to 2015. Conclusions. There was a moderate correlation between interpreted results of 2-hour OGTT and CGM (p = 0.03); CGM indicated a greater level of glucose impairment than OGTT. Glucose >200 mg/dL by CGM predicted development of CFRD (p = 0.0002).

Elevation of one hour plasma glucose during oral glucose tolerance testing

OBJECTIVES

In cystic fibrosis (CF) patients, elevations in 1 hr plasma glucose (PG1) during a 75 g oral glucose tolerance test are common, but of unclear long-term clinical relevance. Thus, we examined associations of PG1 with percent-predicted forced expiratory volume in 1 sec (FEV1 % predicted), CF exacerbations, and CF related diabetes (CFRD) development.

STUDY DESIGN

We conducted a retrospective cohort study of 80 pediatric patients with CF (43 males) followed over 5 years in a single CF center. We considered the association between elevated versus normal PG1 (greater vs. no greater than 160 mg/dl) and linear changes in FEV1 % predicted over time for males and female, as well as the odds of a CF exacerbation and the odds of developing CFRD.

RESULTS

No significant difference in FEV1 % predicted between normal versus elevated PG1 was found at baseline, or over time in males or females. However, males with elevated PG1 tended to have worse FEV1 % predicted over time than those with normal PG1 (reduction of 0.9 FEV1 % predicted/year, 95%CI: -2.5, 0.6). Subjects with PG1 > 160 mg/dl were more likely to develop CFRD (OR 4.5, 95%CI: 1.7, 18.7, P = 0.04) but CF exacerbation risk was similar in both groups.

CONCLUSION

The risk of CFRD increases with PG1 > 160 mg/dl. No statistically significant evidence of an association between elevated PG1 and pulmonary function was found, yet our results do not exclude the possibility that in males, elevated PG1 may signal adverse changes in FEV1 % predicted over time. This possibility requires further study with a larger sample size.

Advances in the detection and management of cystic fibrosis related diabetes

PURPOSE OF REVIEW

This review will outline the screening, diagnosis and management of cystic fibrosis related diabetes (CFRD). It will also discuss advances in the detection of early glucose abnormalities, their clinical significance and the emerging role for early insulin therapy.

RECENT FINDINGS

Before the onset of diabetes (as currently defined), patients with cystic fibrosis (CF) display glucose abnormalities, detectable either by 30-minutely sampled oral glucose tolerance testing (OGTT), or by continuous ambulatory interstitial glucose monitoring (CGM). These early glucose abnormalities are associated with the presence of glucose in airway fluid, potentially promoting the growth of airway pathogens and contributing to the progression of respiratory disease. Progressive insulin deficiency underlies these glucose abnormalities, and insulin deficiency also causes catabolism. Pilot studies of once-daily insulin therapy in the early stages of insulin deficiency show improved lung function and weight gain (important predictors of survival in CF).

SUMMARY

Early stages of insulin deficiency may be contributing to catabolism and deteriorating lung function in CF. It is plausible that early insulin therapy may prevent this deterioration, a view supported by pilot studies. Randomized controlled trials of early insulin therapy will now determine whether insulin therapy should be commenced earlier than current practice in CF.

Clinical and demographic factors associated with post-lung transplantation survival in individuals with cystic fibrosis

BACKGROUND

Contemporary studies evaluating post-transplant survival are limited and often include data from single centers or selected sub-groups. The purpose of this study was to evaluate overall transplant survival and to identify risk factors associated with death after transplant.

METHODS

The Canadian Cystic Fibrosis Registry, a population-based cohort, was used to describe survival after lung transplant. Pre-transplant factors associated with post-transplant survival were estimated using Cox proportional hazards models.

RESULTS

Between 1988 and 2012, 580 patients received a lung transplant. In the entire cohort, post-lung transplant 1-year survival was 87.8%, 5-year survival was 66.7%, and 10-year survival was 50.2%. Median post-transplant survival was 3.3 years (95% confidence interval [CI] = 2.13-6.56) in patients infected with Burkholderia cepacia complex compared with 12.36 years (95% CI = 10.34-17.96) in patients without B cepacia infection (hazard ratio [HR] = 2.63, 95% CI = 2.0-3.44). After adjustment, there was a non-significant trend toward better post-transplant survival with increasing year of transplant (HR = 0.98, 95% CI = 0.96-1.00). Pancreatic sufficiency (HR = 2.13, 95% CI = 1.41-3.20) and age at transplant such that youngest and oldest had the poorest survival (p < 0.001) were significant negative predictors of survival. The risk of death after transplant for patients infected with B cepacia was highest within the first year (HR = 6.29, 95% CI = 3.87-10.21) but remained elevated >1 year after transplant (HR = 1.92, 95% CI = 1.33-2.77) compared with patients without B cepacia infection.

CONCLUSIONS

After lung transplantation, 5-year survival in Canadians with CF is 67%, and 50% of patients live >10 years. Despite these impressive probabilities, age at transplant, pancreatic sufficiency and B cepacia infection remain important determinants of survival after lung transplantation.

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.

HbA1c as a screening tool for cystic fibrosis related diabetes

AIMS

Early diagnosis of cystic fibrosis (CF) related diabetes (CFRD) is important to improve outcomes. International guidelines recommend an oral glucose tolerance test (OGTT) for all CF patients aged ≥10 years - this approach is controversial. The aim of this study was to develop an effective screening tool and reduce the need for a universal OGTT.

METHODS

Adult CF patients (without CFRD) attending an annual review assessment were recruited prospectively (March 2009-July 2012) into two sequential studies - a primary investigative study followed by validation study. All patients underwent an OGTT and were simultaneously screened by predetermined biochemical/clinical criteria to identify their risk of CFRD. A sensitivity/specificity analysis was performed using the World Health Organisation diabetes criteria as gold standard; modifications were made to improve the screening tool's accuracy and determine the optimal screening thresholds. This was tested in the validation study.

RESULTS

429 patients (primary, n=94; validation, n=335: mean age=31.7 ± 10.4(SD), 43% female, 77% on pancreatic supplements). Primary study: in predicting a positive OGTT, the test sensitivity was 66.7% and specificity 60%. HbA1c was carried over to the validation study as it was the most discriminative (optimal threshold ≥5.8% (40 mmol/mol); receiver operating curve, ROC, score 0.60). Validation study: the number of patients with a normal, impaired and diabetic OGTT was 268(80%), 51(15.2%) and 16(4.8%), respectively. HbA1c provided a test sensitivity, specificity and ROC score of 93.8%, 53.0% and 0.73, respectively.

CONCLUSIONS

The use of HbA1c ≥ 5.8%(40 mmol/mol) is an effective tool for CFRD screening and reduced the need for an OGTT by 50.7%.