Diabetes: a major co-morbidity of cystic fibrosis

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

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

The Potential Causes of Cystic Fibrosis-Related Diabetes

Cystic fibrosis (CF) is a genetic disease caused by mutations in the cystic fibrosis transmembrane conductance regulator gene (CFTR). Cystic fibrosis-related diabetes (CFRD) is the most common comorbidity, affecting more than 50% of adult CF patients. Despite this high prevalence, the etiology of CFRD remains incompletely understood. Studies in young CF children show pancreatic islet disorganization, abnormal glucose tolerance, and delayed first-phase insulin secretion suggesting that islet dysfunction is an early feature of CF. Since insulin-producing pancreatic β-cells express very low levels of CFTR, CFRD likely results from β-cell extrinsic factors. In the vicinity of β-cells, CFTR is expressed in both the exocrine pancreas and the immune system. In the exocrine pancreas, CFTR mutations lead to the obstruction of the pancreatic ductal canal, inflammation, and immune cell infiltration, ultimately causing the destruction of the exocrine pancreas and remodeling of islets. Both inflammation and ductal cells have a direct effect on insulin secretion and could participate in CFRD development. CFTR mutations are also associated with inflammatory responses and excessive cytokine production by various immune cells, which infiltrate the pancreas and exert a negative impact on insulin secretion, causing dysregulation of glucose homeostasis in CF adults. In addition, the function of macrophages in shaping pancreatic islet development may be impaired by CFTR mutations, further contributing to the pancreatic islet structural defects as well as impaired first-phase insulin secretion observed in very young children. This review discusses the different factors that may contribute to CFRD.

Peak glucose during an oral glucose tolerance test is associated with future diabetes risk in adults with cystic fibrosis

AIMS/HYPOTHESIS

Cystic fibrosis-related diabetes (CFRD) affects up to 50% of adults with cystic fibrosis (CF) and its presence is associated with adverse effects on nutritional status and pulmonary function. Early diagnosis could minimise CFRD morbidity, yet current methods of an OGTT at 0 and 2 h yield unreliable results. Our aim was to determine which indices from a 2 h OGTT with sampling every 30 min might improve prediction of CFRD.

METHODS

Cross-sectional analysis at baseline (n = 293) and observational prospective analysis (n = 185; mean follow-up of 7.5 ± 4.2 years) of the Montreal Cystic Fibrosis Cohort were performed. Blood glucose and insulinaemia OGTT variables were studied in relation to lung function (forced expiratory volume in 1 s [FEV1]), BMI and risk of developing CFRD.

RESULTS

At baseline, maximum OGTT glucose (G_max) was negatively associated with FEV1 (p = 0.003). Other OGTT values, including classical 2 h glucose, were not. A higher G_max was associated with lower insulin secretory capacity, delayed insulin peak timing and greater pancreatic insufficiency (p < 0.01). G_max was positively associated with the risk of developing CFRD (p = 0.0029); no individual with a G_max < 8 mmol/l developed CFRD over the following decade. No OGTT variable correlated to the rate of change in BMI or FEV1.

CONCLUSIONS/INTERPRETATION

In adults with CF, G_max is strongly associated with the risk of developing CFRD; G_max < 8 mmol/l could identify those at very low risk of future CFRD. G_max is higher in individuals with pancreatic insufficiency and is associated with poorer insulin secretory capacity and pulmonary function.

Overview of Atypical Diabetes

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

Influence of Cystic Fibrosis-Related Diabetes on Mental Health in Adults: A Single-Center Study

PURPOSE

People with cystic fibrosis (CF) are predisposed to chronic conditions, such as CF-related diabetes (CFRD). Recent attention has been focused on the addition of screening for anxiety and depression in the CF population. Independently, CFRD and mental health conditions are associated with worse clinical outcomes; however, research assessing the impact of both conditions together is limited. We aimed to characterize the association between CFRD and selected diagnoses of anxiety or depressive disorders on clinical outcomes in adults with CF.

METHODS

A single-center, retrospective, cross-sectional study in adult patients with CF was performed. Group comparisons included selected diagnoses of depression, anxiety, and CFRD using two-sample t-tests or rank-sum tests for continuous variables, and Chi-square or Fisher's exact tests for categorical variables.

RESULTS

A total of 209 adults were enrolled (mean age of 31.4 ± 11.4 years). Those with a selected diagnoses of depression had a significantly higher proportion of CFRD than those without depression (48% vs. 28%, respectively, p = 0.005), and CFRD was associated with increased odds of depression [OR (CI) = 2.33 (1.28, 4.26), p = 0.006]. We did not see a higher proportion of adults with CFRD and selected diagnoses of anxiety than those without anxiety (41% vs. 31% respectively, p = 0.12), nor an increased odds of anxiety in those with CFRD [OR (CI) = 1.58 (0.88, 2.84), p = 0.12].

CONCLUSION

We show a significant association between CFRD and selected diagnoses of depression in a cohort of adult patients.

Pancreatic islet dysfunction in type 2 diabetes mellitus

Islet dysfunction is a hallmark of type 2 diabetes mellitus (T2DM). Compelling evidence suggests that accumulation of islet amyloid in the islets of Langerhans significantly contribute to β-cell dysfunction and diabetes. Emerging evidence implicates a role for cystic fibrosis transmembrane-conductance regulator in the regulation of insulin secretion from pancreatic islets. Impaired first-phase insulin responses and glucose homeostasis have also been reported in cystic fibrosis patients. The transforming growth factor-β protein superfamily is central regulators of pancreatic cell function, and has a key role in pancreas development and pancreatic disease, including diabetes and islet dysfunction. It is also becoming clear that islet inflammation plays a key role in the development of islet dysfunction. Inflammatory changes, including accumulation of macrophages, have been documented in type 2 diabetic islets. Islet dysfunction leads to hyperglycemia and ultimately the development of diabetes. In this review, we describe these risk factors and their associations with islet dysfunction.

Dyslipidemia is not associated with the development of glucose intolerance or diabetes in cystic fibrosis

BACKGROUND

A high-fat, high-calorie diet is recommended in patients with cystic fibrosis (CF) as it improves nutritional status, respiratory health and longevity. In the general population, this diet is associated with the risk of diabetes. It is unknown whether dyslipidemic changes might contribute to the development of CF-related diabetes (CFRD).

OBJECTIVE

This study aimed to (i) characterize dyslipidemia and (ii) examine the association between dyslipidemia and development of glucose intolerance.

METHODS

Prospective observational study with serial assessments of pulmonary function, glucose tolerance, and lipid profile. Due to intrinsically low total, HDL and LDL cholesterol in patients with CF, subjects were characterized as having dyslipidemia if they had i) HDL in the lowest quartile and/or ii) hypertriglyceridemia (≥1.7 mmol/L).

RESULTS

A total of 256 patients with CF were included (age: 25.5 ± 7.7 years; BMI: 21.7 ± 3.0 kg/m2; FEV1%: 73.2 ± 22.1%; pancreatic insufficiency: 87%). Amongst these patients, 22.7% had low HDL, 9.0% had hypertriglyceridemia and 3.9% had mixed dyslipidemia. There were no differences in HbA1c (p = 0.583) or estimated insulin resistance [HOMA-IR (p = 0.206) or Stumvoll index (p = 0.397)]. Patients with hypertriglyceridemia had higher fat mass (p = 0.038) and fewer had pancreatic insufficiency. Lipid profiles were similar between subjects with CF and subjects with de novo CFRD. There was no effect of low HDL or hypertriglyceridemia on the development of CFRD over 10 years (p = 0.683).

CONCLUSION

In adult patients with CF, dyslipidemia is not associated with the risk of developing hyperglycemia or CFRD.

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.

Hepatic enzyme ALT as a marker of glucose abnormality in men with cystic fibrosis

AIM

Cystic fibrosis (CF) patients are at high risk of developing CF-related diabetes (CFRD). In non-CF patients, liver disease, specifically steatosis and non-alcoholic fatty liver disease (NAFLD), is strongly associated with type 2 diabetes. We compared glycemic status and metabolic profiles in CF patients according to a biomarker of hepatic injury, alanine aminotransferase (ALT).

METHODS

We conducted a cross-sectional study among 273 adult CF patients recruited from the Montreal CF Cohort. A 2-hour oral glucose tolerance test (OGTT) was performed to collect glucose and insulin measures every 30 minutes. Fasting ALT levels and anthropometric measures were also obtained. Patients were categorized into 2 groups based on ALT cut-off of 25 U/L.

RESULTS

Patients in the high ALT group were mostly men (83%), had higher mean weight and BMI (p<0.001) and showed elevated glucose levels throughout OGTT (p≤0.01). When stratified by sex, only men with high ALT showed significantly higher weight (p<0.001), higher glycemic values at 60, 90 and 120 minutes of OGTT (p≤0.01), higher frequency of de novo CFRD (20.5% vs 8.2%, p = 0.04) as well as lower insulin sensitivity than men with normal ALT (p = 0.03). ALT levels were strongly associated with HOMA-IR in CFRD patients (p = 0.001, r2 = 0.28).

CONCLUSIONS

Adult CF men with higher ALT show an increased frequency of dysglycemia and de novo CFRD, lower insulin sensitivity and higher eight. Our data suggests that ALT levels could be an interesting tool to guide targeted diabetes screening, particularly among CF men. Prospective studies are needed to confirm these observations.

Understanding patient activation and adherence to nebuliser treatment in adults with cystic fibrosis: responses to the UK version of PAM-13 and a think aloud study

BACKGROUND

Patient activation refers to patients' knowledge, skills, and confidence in self-managing health conditions. In large cross-sectional studies, individuals with higher patient activation are observed to have better health outcomes with the assumption that they are more engaged in health self-management. However, the association between patient activation and objectively measured self-care indicators in individuals can be inconsistent. This research investigated the role of patient activation as measured by the UK Patient Activation Measure (PAM-13) in adults with Cystic Fibrosis (CF). The aims were twofold: to explore how adults with CF interpret and respond to the PAM-13; and to investigate the association between PAM-13 and objectively measured nebuliser adherence in UK adults with CF.

METHODS

This article describes two studies which examined the PAM-13 from different perspectives. Study 1 comprised 'think aloud' interviews with 15 adults with CF. The data were analysed using an a priori coding framework. Study 2 examined the association between PAM-13 and objectively measured nebuliser adherence in 57 adults with CF.

RESULTS

Study 1 showed that adults with CF encountered several difficulties while completing the PAM-13. The difficulties were related to understanding how to interpret aspects of CF in order to respond (i.e., control over the condition, ability to exercise) and item wording. Some adults with CF responded to the PAM-13 in an optimistic way in relation to what they thought they should do rather than what they actually do. These findings were echoed by the results of Study 2, which showed that PAM-13 scores were not significantly correlated with objective medication adherence in a different sample. This article synthesises the results of both studies, providing insights into influences and associations of patient activation as measured by the UK PAM-13 in adults with CF.

CONCLUSIONS

There were some significant difficulties created by the wording of the UK PAM-13 for adults with CF. This may partly explain the finding that PAM-13 scores were not related to objectively measured nebuliser adherence in this study. The UK PAM-13 would benefit from further research to verify its validity and reliability in different patient populations against objective measures of behaviour rather than simply self-report.

Incidence and risk factors of paediatric cystic fibrosis-related diabetes

INTRODUCTION

Cystic fibrosis-related diabetes (CFRD) is a common complication of cystic fibrosis (CF) directly linked to increased morbidity and mortality. Both the incidence of type I and type II diabetes has been shown to increase in the general population. In this study, we investigated the incidence and risk factors of CFRD in a paediatric CF population.

METHODS

Prospectively collected data from the Canadian CF Registry (CCFR) from 2000 to 2016 for patients ages 10 to 18 years was used to determine the incidence of CFRD. Risk factors for CFRD in the Canadian population were investigated using a nested case-control design. Conditional logistic regression analysis with a 4:1 control: case matching was used.

RESULTS

From 2000 to 2016, 2326 patients with CF aged between 10 through 18 years were included in the CCFR, during this time the overall incidence rate of CFRD was 2.1 cases per 100 patient-years (95% confidence interval 1.8 to 2.3). Incidence rates were stable in the Canadian cohort over three consecutive time periods 2000-2005, 2006-2010; 2011-2016. Worse lung function, female gender, history of allergic bronchopulmonary aspergillosis, Gastrostomy tube insertion and liver disease were statistically significant risk factors for CFRD.

CONCLUSION

The incidence of CFRD in the Canadian paediatric population has been stable over time, in contrast to the rising rates of Type 1 and Type 2 diabetes in the general paediatric population. The risk factor for CFRD in this contemporary population were consistent with previous studies.

Islet Transplantation in Children

PURPOSE OF REVIEW

Transplantation of the islets of Langerhans or the pancreas aims to restore blood sugar control. We review both forms of transplantation in children.

RECENT FINDINGS

Allogenic islet transplantation typically in to the liver via the portal vein may be a potential alternative to pancreas transplantation in the future. Autologous islet transplantation after total pancreatectomy is effective for debilitating symptoms of recurrent and chronic pancreatitis. Chronic pancreatitis in children is most often related to genetic mutations but is otherwise similar to adults with eventual exocrine and endocrine failure. Removal of the pancreas ameliorates pain, and islet transplantation preserves endocrine function to the extent allowed by the damage sustained by the pancreas from chronic inflammation. Despite the complexity of the operative procedure, the outcome of total pancreatectomy and autologous islet transplantation in children has been excellent including quality of life.

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.

The main mechanism associated with progression of glucose intolerance in older patients with cystic fibrosis is insulin resistance and not reduced insulin secretion capacity

BACKGROUND

Aging cystic fibrosis (CF) patients are at high risk of developing CF-related diabetes (CFRD). Decrease in insulin secretion over time is the main hypothesis to explain this increasing prevalence but mechanisms are still not well elucidated. The objective is to assess evolution of glucose tolerance and insulin secretion/sensitivity in aging CF patients.

METHODS

This is a retro-prospective observational analysis in the older adult CF patients from the Montreal Cystic Fibrosis Cohort (n = 46; at least 35 years old at follow-up) and followed for at least 4 years. Baseline and follow-up (last visit to date) 2-h oral glucose tolerance test (OGTT with glucose and insulin measurements every 30 min) were performed. Pulmonary function test (FEV₁) and anthropometric data were measured the same day. Insulin sensitivity was measured by the Stumvoll index.

RESULTS

After a mean follow-up of 9.9 ± 2.6 years, mean age at follow-up was 43.5 ± 8.1 years old. An increase of body weight (+2.6 ± 6.5 kg, p = 0.01) and a decrease in pulmonary function (FEV₁; 73.4 ± 21.2% to 64.5 ± 22.4%, p ≤ 0.001) were observed. Overall, insulin secretion is maintained at follow-up but all OGTT glucose values increased (for all values, p ≤ 0.028). At follow-up, 28.3% of patients had a normal glucose tolerance while 71.7% had abnormal glucose tolerance (AGT). AGT patients decreased their insulin sensitivity over time (p = 0.029) while it remained the same in NGT patients (p = 0.917).

CONCLUSION

In older CF patients, the progression of impaired glucose tolerance is occurring with stable insulin secretion but reduced insulin sensitivity.

Vitamin D3 supplementation among adult patients with cystic fibrosis

BACKGROUND & AIMS

Vitamin D (Vit D) deficiency in cystic fibrosis (CF) is partially secondary to exocrine pancreatic insufficiency. Our aim was to establish a Vit D₃ supplementation protocol that will increase 25(OH)D to the recommended level (30 ng/mL).

METHODS

Retrospective study of 200 patients (≥18 years) conducted from February 2007 to June 2014 at the CF clinic of the Centre Hospitalier de l'Université de Montréal. Vit D₃ supplementation protocol was 1600 IU/day or 10,000 IU/week during the summer (May 1st to October 31st) and 3200 IU/day or 20,000 IU/week during the winter (November 1st to April 30th), in addition to the 1200 IU/day included in multivitamins.

RESULTS

Significant increase in serum 25(OH)D levels from baseline (25.9 ± 10.3 ng/mL) to follow-up (37.0 ± 11.4 ng/mL) (P ≤ 0.001). At follow-up, increased doses during the winter improved serum 25(OH)D levels to a degree comparable to the summer.

CONCLUSIONS

This supplementation protocol is efficient and needs to be tested in other CF adult cohorts and correlated to potential health benefit measurements.

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.

Could T cells be involved in lung deterioration and hyperglycemia in cystic fibrosis?

Cystic fibrosis-related diabetes (CFRD) is the most frequent complication of cystic fibrosis (CF) and associated with increased mortality. Why patients have an accelerated loss of lung function before the diagnosis of CFRD remains poorly understood. We reported that patients with or without CFRD had increased glucose excursions when compared to healthy peers. Studies have demonstrated that patients with CF have increased glucose fluctuations and hyperglycemia and that this may affect the clinical course of CF and lead to lymphocyte dysfunction. T-helper 17 (Th17) lymphocytes produce and secrete the pro-inflammatory cytokine IL-17. The Th17 pathway is involved in CF lung inflammation, β-cell destruction in type 1 diabetes (T1D) and Th17 cells of patients with type 2 diabetes have increased production of IL-17 when compared to healthy peers. Also, regulatory T-cells (Tregs) have been shown to be dysfunctional and produce IL-17 in T1D. Furthermore, vitamin D can affect inflammation in CF, diabetes and the differentiation of lymphocytes. In this review, we discuss the potential roles of hyperglycemia on Th17 cells, Tregs and IL-17 as a potential cause for accelerated lung function decline before CFRD and how this could be modulated by vitamin D or by directly intervening in the IL-17A pathway.

Impact of sex on insulin secretion in cystic fibrosis

CONTEXT

Cystic fibrosis-related diabetes is primarily due to a defect in insulin secretion. Women with cystic fibrosis (CF) are at higher risk of developing CF-related diabetes.

OBJECTIVE

The objective of the study was to examine sex differences in insulin and glucose homeostasis. We hypothesized that in CF, women would display lower insulin secretion than men.

DESIGN

This was a study based on an ongoing observational CF cohort with a mean follow-up of 19.9 ± 5.2 months.

SETTING

The study was conducted at the CF clinic of the Centre Hospitalier de l'Université de Montréal (Québec, Canada).

PATIENTS

From 230 adults with CF (123 men, 107 women) of similar age and functional pulmonary status, 104 retested after the follow-up. Age-matched healthy individuals (25 men, 19 women) were included in the study.

INTERVENTIONS

Participants underwent a 2-hour oral glucose tolerance test with 30-minute interval sample measurements.

MAIN OUTCOME MEASURE

Plasma insulin and glucose levels were measured.

RESULTS

Women with CF had higher overall insulin secretion as compared with men with CF (P ≤ .05) but similar to healthy women (P = .606). Men with CF had lower overall insulin secretion than healthy men (P = .020) and higher insulin sensitivity (P = .009) than women with CF. PATIENTS with CF displayed higher overall glucose excursions than healthy patients. Sex-related differences were still observed in the CF cohort after follow-up.

CONCLUSIONS

Surprisingly, in CF, adult women presented higher insulin secretion than adult men at a comparable level with what is observed in healthy individuals. Potential implications of this sex dimorphism in CF remain to be established.

Plasma zinc in adults with cystic fibrosis: correlations with clinical outcomes

BACKGROUND

Zinc status has been previously documented in cystic fibrosis (CF) infants, children and adolescents. However, despite the increasing life expectancy observed in CF populations, data regarding zinc status of CF adults are surprisingly lacking. The objectives of this study were to (1) characterize zinc status and (2) explore associations between zinc status and clinical outcomes of CF adult patients.

METHODS

A retrospective chart review was performed for patients who had their plasma zinc measured between 2009 and 2012. Data included demographics, clinical characteristics, biochemical parameters and co-morbid conditions.

RESULTS

A total of 304 CF patients were included in the study. These patients displayed a good nutritional status (mean BMI±SD: 22.7±3.5) and moderate lung disease (mean FEV1±SD: 66.3±22.2). Low plasma zinc concentration (<9.2μmol/L) was found in 68 out of 304 CF patients (22.4%). Compared to patients with normal zinc, those with low zinc had significantly lower forced vital capacity and forced expiratory volume in one second. 72% of CF adults with low zinc suffered from bone disease (vs 49% with normal zinc, p=0.037) and 79% had impaired glycemic status (vs 58%, p=0.016). Accordingly, negative correlations were found between plasma zinc and glucose (r=-0.139, p=0.0001), HbA1c (r=-0.237, p=0.0001) and fructosamine (r=-0.134, p=0.034). In multiple linear regression, albumin and glycemic status were significant predictors of plasma zinc.

CONCLUSION

Our data indicated that nearly one quarter of CF adults with good nutritional status and moderate lung disease had low plasma zinc concentration and that low zinc status was associated with worse clinical outcomes.

Diagnosis of cystic fibrosis-related glucose abnormalities: Can we shorten the standard oral glucose tolerance test?

Adult patients with cystic fibrosis (APCF) are at high risk of developing impaired glucose tolerance (IGT) and CF-related diabetes (CFRD) and thus an annual screening with a 2-h oral glucose tolerance test (OGTT) is recommended. This population would greatly benefit from a simplified and harmless alternative to the standard OGTT. Thus, we aimed to compare the diagnostic values of HbA1c and glycemias at interval time points during the 2-h OGTT for IGT and CFRD detection in APCF. To do so, we conducted a cross-sectional analysis of 194 APCF with normal fasting plasma glucose values (≤ 7.0 mmol · L(-1)) who underwent a 2-h OGTT. Receivers operating characteristic area under the curves (ROC-AUC) were analyzed to assess the diagnostic value of HbA1c and intermediate OGTT glycemias using 2-h OGTT glycemia as reference. For both IGT and CFRD diagnoses, ROC-AUC values obtained from glycemia at 90 min were significantly higher than HbA1c and remaining intermediate glycemias (p < 0.001). The best 90-min OGTT cut-off values for these diagnoses were >9.3 mmol · L(-1) (IGT) and ≥ 11.5 mmol · L(-1) (CFRD). A 90-min OGTT glycemia might be a simplified alternative to 2-h OGTT glycemia for earlier glucose tolerance abnormalities diagnosis in APCF. This finding should be confirmed in other APCF cohorts and its predictive value should be established prospectively.

Cystic fibrosis-related diabetes in older adolescents: parental support and self-management

PURPOSE

The purpose of this study was to describe the experience of cystic fibrosis-related diabetes (CFRD), parental support of adolescent self-management, and the relationship of parental autonomy support with disease self-management.

DESIGN AND METHODS

Semi-structured interviews and questionnaires were employed in a study conducted with 10 adolescents and their parents.

RESULTS

Parents and adolescents lacked confidence to manage CFRD. Mothers' autonomy support was associated with adolescents' CFRD competence and cystic fibrosis self-care. Fathers' autonomy support was associated with mothers' reports of adolescent cystic fibrosis self-care.

PRACTICE IMPLICATIONS

Education about CFRD management and support of adolescent autonomy in disease management is needed.

Update on diagnosis and monitoring of cystic fibrosis-related diabetes mellitus (CFRD)

Cystic fibrosis (CF) is the most common recessive autosomal disease among Caucasian. Children with CF have benefitted from advances in medical and nutritional treatments, and this can be gleaned from the improvement in the survival of these patients. The increase in the survival rate brought with it the appearance of co-morbidities related to CF. Nowadays cystic fibrosis-related diabetes (CFRD) is considered the most common complication associated with CF. It can appear as early as infancy or adolescence, and its prevalence can be as high as 50% in adult patients. Because of its high prevalence, difficulties in early detection and the risks involved, in recent years several studies and consensuses have focused on this condition, adding information about the epidemiology, pathophysiology, prognosis and treatment of CFRD. The main aspects of these new concepts, as well as the current recommendations for its diagnosis and follow-up, will be presented in this study.

[Endocrine complications of cystic fibrosis in childhood]

Since the 20 last years, the median age of survival has dramatically improved in children suffering from cystic fibrosis and complications such as growth retardation, pubertal delay and low bone mineral density are now more often than not observed in affected adolescents. The severity of the disease and the poor nutritional status due to pancreatic insufficiency and malabsorption are commonly implicated but recent data suggest that the disease could also play a role though the alteration of the chlore chanel (CFTR). Furthermore an increase prevalence of glucose intolerance and diabetes due to the progressive β cells destruction is observed in these children that make the life sometimes difficult for these adolescents already affected by an heavy chronic disease. The monitoring of the children should thus now become pluridisciplinary and include regular clinical evaluation of height and pubertal status, mineral bone density by DEXA and OGTT every two years since 10 years of age. Therefore, in addition to the standard treatment of cystic fibrosis is now added the vitamin D supplementation, the subcutaneous insulin therapy and may be the growth hormone that could be a new therapeutic demonstrating beneficial effects in these chronic disease. However further studies need to be performed to improve the management of these new endocrine complications more and more frequent in children and adolescents suffering from cystic fibrosis.

Bisphosphonates for osteoporosis in people with cystic fibrosis

BACKGROUND

Osteoporosis is a bone mineralisation disorder occurring in about one third of adults with cystic fibrosis. Bisphosphonates can increase bone mineral density and decrease the risk of new fractures in post-menopausal women and people receiving long-term oral corticosteroids.

OBJECTIVES

To assess the effects of bisphosphonates on the frequency of fractures, bone mineral density, quality of life, adverse events, trial withdrawals, and survival in people with cystic fibrosis.

SEARCH METHODS

We searched the Cystic Fibrosis and Genetic Disorders Group Trials Register of references (identified from electronic database searches and handsearches of journals and abstract books) on 15 February 2012.Additional searches of PubMed were performed on 14 May 2011.

SELECTION CRITERIA

Randomised controlled trials of at least six months duration studying bisphosphonates in people with cystic fibrosis.

DATA COLLECTION AND ANALYSIS

Two authors independently selected trials and extracted data. Trial investigators were contacted to obtain missing data.

MAIN RESULTS

Nine trials were identified and seven (with a total of 237 adult participants) were included.Data were combined (when available) from six included studies in participants without a lung transplant. Data showed that there was no significant reduction in fractures between treatment and control groups at 12 months, odds ratio 0.72 (95% confidence interval 0.13 to 3.80). No fractures were reported in studies with follow-up at 24 months. However, in patients taking bisphosphonates after six months the percentage change in bone mineral density increased at the lumbar spine, mean difference 4.61 (95% confidence interval 3.90 to 5.32) and at the hip or femur, mean difference 3.35 (95% confidence interval 1.63 to 5.07); but did not significantly change at the distal forearm, mean difference -0.49 (95% confidence interval -2.42 to 1.45). In patients taking bisphosphonates, at 12 months the percentage change in bone mineral density increased at the lumbar spine, mean difference 6.10 (95% confidence interval 5.10 to 7.10) and at the hip or femur, mean difference 4.35 (95% confidence interval 2.99 to 5.70). At 24 months, in patients treated with bisphosphonates the percentage change in bone mineral density also increased at the lumbar spine, mean difference 5.49 (95% confidence interval 4.38 to 6.60) and at the hip or femur, mean difference 6.05 (95% confidence interval 3.74 to 8.36). There was clinical heterogeneity between studies and not all studies reported all outcomes. Bone pain was the most common adverse event with intravenous agents. Flu-like symptoms were also increased in those taking bisphosphonates.In participants with a lung transplant (one study), intravenous pamidronate did not change the number of new fractures. At axial sites, bone mineral density increased with treatment compared to controls: percentage change in bone mineral density at lumbar spine, mean difference 6.20 (95% confidence interval 4.28 to 8.12); and femur mean difference 7.90 (95% confidence interval 5.78 to 10.02).

AUTHORS' CONCLUSIONS

Oral and intravenous bisphosphonates increase bone mineral density in people with cystic fibrosis. Severe bone pain and flu-like symptoms may occur with intravenous agents. Additional trials are needed to determine if bone pain is more common or severe (or both) with the more potent zoledronate and if corticosteroids ameliorate or prevent these adverse events. Additional trials are also required to further assess gastrointestinal adverse effects associated with oral bisphosphonates. Trials in larger populations are needed to determine effects on fracture rate and survival.

Insulin production and resistance in cystic fibrosis: effect of age, disease activity, and genotype

AIM

To assess the major determinants of glucose tolerance between age, genotype, and clinical status in cystic fibrosis (CF) patients, and study if defects of insulin secretion and insulin sensitivity were associated with the onset of CF-related diabetes (CFRD).

SUBJECTS AND METHODS

One hundred and nineteen patients, in stable clinical condition were studied. They were subdivided into 3 groups based on age, and 2 groups based on Schwachman-Kulczycki clinical score. All patients were genotyped, and subsequently divided into 3 groups. Ninety-four healthy normal-weight controls, comparable for sex and age were also studied. All subjects had baseline blood samples taken for glucose and insulin, C-peptide, and glycated hemoglobin. Homeostasis model assessment of insulin resistance (HOMA-IR), fasting glucose/insulin ratio (FGIR) were calculated as indices of IR and insulinogenic index as a marker of pancreatic β-cell function. All patients underwent an oral glucose tolerance test, and 57 underwent an IVGTT for the calculation of first-phase (FPIR) and acute insulin responses (AIR).

RESULTS

The F508del homozygous patients had an increased chance of developing impaired glucose tolerance (IGT) and significantly lower FPIR, decreased HOMA-IR, and insulinogenic index. Heterozygote F508del patients had an increased chance of having normal glucose tolerance. HOMA-IR, FGIR, and insulinogenic index did not change with age or clinical score. HOMAIR correlated with FPIR. FPIR correlated positively with insulinogenic index. AIR correlated negatively with FGIR, and positively with C-reactive protein. In multiple linear regression analyses, glucose tolerance was related to the agegroup, and to the HOMA-IR and insulinogenic indexes.

CONCLUSIONS

IGT and CFRD were related mainly to genotype, although, as expected, the prevalence increased with age. The data suggested a possible combined contribution of insulin deficiency, β-cell function, and reduced insulin sensitivity to the onset of CFRD; however, further studies are warranted to better elucidate this aspect.

Long-term benefits in lung function and nutritional status of strict metabolic control of cystic fibrosis-related diabetes

Cystic fibrosis related diabetes (CFRD) is a strong determinant for lung function decline and increased mortality. Insulin treatment of CFRD is reportedly beneficial for this situation. We report on the long-term impact of insulin treatment of CFRD on pulmonary function and nutritional status in a CF male patient since diagnosis of diabetes. We report the case of a patient diagnosed with CF at the age of 16. Two years later, he experienced a rapidly evolving decrease in pulmonary function, some months later criteria were met warranting lung transplantation. Concomitantly, he was diagnosed with CFRD and insulin therapy was started. Lung function (spirometry), nutritional status (body mass index) and metabolic control (HbA(1c)) were determined every 3 months. After the introduction of insulin treatment, pulmonary function and nutritional status progressively improved and good glycemic control was achieved. The significant and sustained improvement in pulmonary function allowed for the patient's withdrawal from the lung transplantation program within 4 months, a situation which has been maintained until now, 8 years later. The long follow-up of our patient documents the rapid and prolonged beneficial effect of proper metabolic control of CFRD on the respiratory deterioration in CF.

Diabetic keto-acidosis as a presentation of cystic fibrosis-related diabetes: a case report

Cystic fibrosis (CF) is one of the most common genetically inherited diseases and often complicated by diabetes mellitus. With increasing longevity, the incidence and prevalence of cystic fibrosis-related diabetes (CFRD) rise and microvascular complications develop. CFRD is an entity on its own with characteristics seen in both type 1 and type 2 diabetes. Keto-acidosis, a potentially life-threatening complication of diabetes, is an extremely rare presentation of CFRD. Here we present the history of a 21-year-old CF patient with no prior diagnosis of CFRD who developed keto-acidosis after an episode of pulmonary infection. Based on this case report we would like to emphasize the importance of screening for and early treatment of CFRD. We also discuss the management policy of CFRD and when and whether to initiate insulin therapy.

Iron and CF-related anemia: expanding clinical and biochemical relationships

INTRODUCTION

This cross-sectional study was conducted to assess the relationship between iron levels in the plasma and sputum of cystic fibrosis (CF) patients.

METHODS

Demographic, clinical, and iron-related laboratory data were prospectively obtained from 25 patients with stable clinical features and 14 patients with worsened clinical features since their most recent evaluations.

RESULTS

Compared to patients with stable clinical features, those who experienced clinical deterioration demonstrated significantly worse lung function and were more frequently malnourished and diabetic. Members of the latter group were also significantly more hypoferremic and had higher sputum iron content than patients with stable clinical features. No significant correlation was found between plasma and sputum iron levels when the groups were analyzed together and separately.

CONCLUSIONS

Sputum iron content does not correlate with iron-related hematologic tests. Hypoferremia is common in CF and correlates with poor lung function and overall health.

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.

HE3286, an oral synthetic steroid, treats lung inflammation in mice without immune suppression

Background

17α-Ethynyl-5-androsten-3β, 7β, 17β-triol (HE3286) is a synthetic derivative of an endogenous steroid androstenetriol (β-AET), a metabolite of the abundant adrenal steroid deyhdroepiandrosterone (DHEA), with broad anti-inflammatory activities. We tested the ability of this novel synthetic steroid with improved pharmacological properties to limit non-productive lung inflammation in rodents and attempted to gauge its immunological impact.

Methods and Results

In mice, oral treatment with HE3286 (40 mg/kg) significantly (p < 0.05) decreased neutrophil counts and exudate volumes (~50%) in carrageenan-induced pleurisy, and myeloperoxidase in lipopolysaccharide-induced lung injury. HE3286 (40 mg/kg) was not found to be profoundly immune suppressive in any of the classical animal models of immune function, including those used to evaluate antigen specific immune responses in vivo (ovalbumin immunization). When mice treated for two weeks with HE3286 were challenged with K. pneumoniae, nearly identical survival kinetics were observed in vehicle-treated, HE3286-treated and untreated groups.

Conclusions

HE3286 represents a novel, first-in-class anti-inflammatory agent that may translate certain benefits of β-AET observed in rodents into treatments for chronic inflammatory pulmonary disease.

Lack of correlation between 1,5-anhydroglucitol assay and oral glucose tolerance test in patients with cystic fibrosis

OBJECTIVE

To determine whether the 1,5-anhydroglucitol (1,5-AG) assay, which reflects serum glucose levels during the preceding 2 weeks, could be used as an alternative to the current standard screening test for cystic fibrosis-related diabetes (CFRD)-the oral glucose tolerance test (OGTT).

METHODS

Serum 1,5-AG, hemoglobin A1c (A1C), fructosamine, and glucose at various time intervals during the OGTT were measured in 10 patients, 19 to 36 years old, with cystic fibrosis. Correlation coefficients were calculated to compare 1,5-AG with A1C, fructosamine, and serum glucose levels during the OGTT, and the mean 1,5-AG, A1C, and fructosamine for normal glucose tolerance, impaired glucose tolerance (IGT), and CFRD were compared statistically.

RESULTS

On the basis of the 120-minute OGTT, 1 of the 10 study subjects had CFRD and 4 had IGT. The mean 1,5-AG for patients with normal glucose tolerance was not significantly different from that for patients with IGT (P = .063). The 1,5-AG value was not significantly correlated with serum glucose during the OGTT, A1C, or fructosamine.

CONCLUSION

In this pilot study, we found no significant correlation between 1,5-AG and glucose values during the OGTT or between 1,5-AG and other glycemic markers. Hence, the utility of the 1,5-AG assay for screening for CFRD in the population of patients with cystic fibrosis may be limited.

[Value of continuous glucose monitoring in screening for diabetes in cystic fibrosis]

AIMS

In the past few years, survival has increased for people with cystic fibrosis (CF). Diabetes is an important complication of CF caused by pancreatic insufficiency, which reduces insulin secretion. Because of increased longevity of patients with CF, the prevalence of CF-related diabetes (CFRD) has increased. CFRD is associated with increased mortality and morbidity. Several studies have reported a decline in nutritional and pulmonary status 2-4 years before the diagnosis of CFRD. The introduction of insulin treatment can produce clinical improvement in weight and lung function. The oral glucose tolerance test is currently the reference method in screening for CFRD, but the current definition of diabetes based on the 2-h post-load plasma glucose level may not be the most accurate method for early detection of glucose tolerance abnormalities in CF. The continuous glucose monitoring system (CGMS) has been described as a useful tool for early detection of hyperglycemia in the CF patient. We tested the CGMS in CF patients with unexplained alteration of their general status. The aim of this study was to assess the value of the CGMS in this population.

METHODS

An annual OGTT (following World Health Organization recommendations) was conducted as a screening test to identify CFRD in patients aged over 10 years or patients aged under 10 years with a poorer clinical status. The CGMS was performed in patients with unexplained worsened clinical status and without diabetes in OGTT.

RESULTS

Forty-two patients aged from 8.5 to 19 years were screened using OGTT for CFRD. According to ADA criteria, 23 patients (54.8%) displayed normal glucose tolerance, 14 (33.3%) impaired glucose tolerance, and 5 diabetes (11.9%). Out of 37 nondiabetic, the CGMS was used in 20 patients with unexplained altered general status. The CGMS revealed peaks of glucose values greater than 2 g/L in 16 patients, 9 patients with normal glucose tolerance, and 7 patients with impaired glucose tolerance. The mean CGMS glucose and time of glycemic monitoring above 1.4 g/L increased in patients with peaks greater than 2 g/L compared to patients without peaks (p=0.0016 and p=0.0069 respectively). After analysis of the CGMS, the prevalence of diabetes increased from 11.9 to 50%. Three patients aged less than 10 years with a normal OGTT profile presented glycemic peaks greater than 2 g/L during CGMS.

CONCLUSION

CGMS revealed more glucose metabolism abnormalities than OGTT in patients with unexplained altered general status.

[Screening and management of glucose metabolism disorders in cystic fibrosis patients. Practices survey in 4 French reference centers]

OBJECTIVE

Glucose metabolism disorders are a new point of interest in cystic fibrosis (CF) management. Cystic fibrosis-related diabetes mellitus (CFRD) increases alteration of pulmonary function as well as patients' morbidity and mortality. In France, CF patients are exclusively followed up in reference centers. We conducted a practices survey on screening and diagnosis of glucose metabolism disorders at 4 French CF centers. The objective of this study was to assess adherence to practice guidelines developed in 2002 at these centers.

METHODS

This study was conducted in 2 sessions: 60 medical records were randomly selected in 2005 and in 2007 for patients aged over 10 years followed up at 4 CF centers. A questionnaire survey was completed for each patient with questions on CFRD screening, diagnosis, monitoring and treatment. Our guidelines recommend random blood glucose (RBG) at each standard biological test, annual glycosylated haemoglobin and an oral glucose tolerance test (OGTT) at 10, 15 and 18 years of age, then every 2 or 3 years.

RESULTS

An annual RBG was performed in 82% of patients in 2005 and 91.5% in 2007. HbA1c screening was performed annually for 77% of patients in the 1st session and for 90% of patients for the 2nd session (p<0.10). Adherence to OGTT guidelines was better for adults than children: 96% had an OGTT during the 3 years of the first session and 79% during the second session, while fewer than 50% of children had their OGTT at 15 and 18 years of age. Taking the OGTT at 10 years of age could not be assessed because no patients were 10 years old during the study period. Screening for neurological complications of CFRD was assessed in the majority of diabetic patients, while half or less than half had annual fundus oculi or microalbuminuria dosage.

DISCUSSION

There was an improvement in screening for CFRD and glucose metabolism disorders between 2005 and 2007, even though practices could still be improved. This shows that clinical guidelines can be implemented and followed. However, screening and management criteria for glucose metabolism disorders must be consensus-based with higher evidence in order to limit the variability of practices and prevent CFRD-related complications.

Bisphosphonates for osteoporosis in people with cystic fibrosis

BACKGROUND

Osteoporosis is a bone mineralisation disorder occurring in about one third of adults with cystic fibrosis (CF). Bisphosphonates can increase bone mineral density (BMD) and decrease the risk of new fractures in post-menopausal women and people receiving long-term oral corticosteroids.

OBJECTIVES

To assess the effects of bisphosphonates on the frequency of fractures, BMD, quality of life, adverse events, trial withdrawals, and survival in people with CF.

SEARCH STRATEGY

We searched the CF and Genetic Disorders Group Trials Register of references (identified from electronic database searches and handsearches of journals and abstract books) on 29 October 2008.Additional searches of Pubmed were performed on 01 November 2008.

SELECTION CRITERIA

Randomised controlled trials of at least six months duration studying bisphosphonates in people with CF.

DATA COLLECTION AND ANALYSIS

Two authors independently selected trials and extracted data. Trial investigators were contacted to obtain missing data.

MAIN RESULTS

Seven trials were identified and five (with a total of 145 adult participants) were included.Data were combined when available from four included studies in participants without a lung transplant. This showed that there was no significant reduction in fractures between groups. However, after six months, the percentage change in BMD increased in those on bisphosphonates at the lumbar spine, mean difference (MD) 4.61 (95% confidence interval (CI) 3.90 to 5.32) and at the hip, MD 3.35 (95% CI 1.63 to 5.07); but did not significantly change at the distal forearm, MD -0.49 (95% CI -2.42-1.45). There was clinical heterogeneity between studies and not all studies reported all outcomes. Bone pain was the most common adverse event with intravenous agents. Flu-like symptoms were also increased in those taking bisphosphonates.In participants with a lung transplant (one study), intravenous pamidronate did not change the number of new fractures. At axial sites, BMD increased with treatment compared to controls: percentage change in bone mineral density at lumbar spine, MD 6.20 (95% CI 4.28 to 8.12) and femur MD 7.90 (95% CI 5.78 to 10.02).

AUTHORS' CONCLUSIONS

Oral and intravenous bisphosphonates increase BMD in people with CF. Severe bone pain and flu-like symptoms may occur with intravenous agents. Additional trials are needed to determine if bone pain is more common or severe (or both) with the more potent zoledronate and if corticosteroids ameliorate or prevent these adverse events. Trials in larger populations are needed to determine effects on fracture rate and survival.

One-year glargine treatment can improve the course of lung disease in children and adolescents with cystic fibrosis and early glucose derangements

BACKGROUND

Diabetes increases morbidity and mortality in cystic fibrosis (CF) patients, but several studies indicate that also prediabetic status may have a potential impact on both nutrition and lung function.

OBJECTIVE

To evaluate the effect of glargine on the clinical course in CF patients with early glucose derangements.

METHODS

CF population was screened for glucose tolerance. CF patients with age >10 yr were screened with fasting hyperglycemia (FH). CF patients with age >10 yr without FH and those with age <10 yr with occasional FH were evaluated for glucose abnormalities on the basis of oral glucose tolerance test and/or continuous glucose monitoring system. All CF patients with glucose derangements were enrolled in an open clinical trial with glargine. Body mass index (BMI) z-score, forced expiratory volume in the first second (FEV(1)), number of acute pulmonary exacerbations and hemoglobin A1c, were as outcome measures at baseline and after 1 yr of treatment.

RESULTS

After 12 months of therapy, BMI z-score improved only in patients with baseline BMI z-score less than -1 (p = 0.017). An 8.8% increase in FEV(1) (p = 0.01) and 42% decrease in the number of pulmonary exacerbations (p = 0.003) were found in the whole group compared with previous 12 months of therapy.

CONCLUSION

Glargine could represent an innovative strategy to prevent lung disease progression in CF patients with early glucose derangements. Larger controlled trials are needed to better clarify the effects of insulin on clinical status in CF patients with early glucose derangements.