Cystic fibrosis-related diabetes in children--gaps in the evidence?

The first report of Methicillin-resistant Staphylococcus aureus (MRSA) in cystic fibrosis (CF) patients in Saudi Arabia

Introduction

Methicillin-resistant Staphylococcus aureus infections have been increasingly reported in patients with cystic fibrosis (CF) who have progressive deterioration in their pulmonary function.

Objectives

To determine the prevalence of MRSA infections in CF in a tertiary care center in Saudi Arabia.

Methodology

This is a retrospective chart review conducted as part of the CF registry data from 1 January 2002 to 1 June 2016. All patients with confirmed CF of all age groups who had a respiratory culture positive for MRSA were included in the study.

Results

Among 385 patients with CF who had respiratory samples, 43 (11%) were positive for MRSA at a mean age of 10.4 ± 7.2 years. Twenty-two patients out of the 43 (51%) were treated with different regimens: nasal Bactroban in 13/22 (59%); a combination of nasal Bactroban, oral vancomycin, and rifampicin for 2 weeks in 5 patients (23%); Bactroban and linezolid in one patient (5%); and oral vancomycin and rifampicin in 3 patients (14%). Eight out of the 22 treated patients (36%) achieved MRSA eradication. Six out of the 22 treated (27%) had experienced MRSA recurrence within 3–6 months, and another 5/22 (23%) continued to have MRSA colonization up to 2–4 years of follow-up despite using a proper eradication protocol. Twelve out of the 43 (28%) patients with MRSA infection died.

Conclusion

MRSA infection in our population with CF is common. Therefore, an eradication protocol should be instituted at an early stage to prevent chronic colonization. Children with persistent MRSA colonization have high morbidity and mortality rate.

Dietary intake in cystic fibrosis and its role in glucose metabolism

BACKGROUND

Dietary intervention in cystic fibrosis (CF) has historically focused on high-energy diets to address malnutrition, with little attention on diet quality. With increased survival, CF complications such as impaired glucose tolerance (IGT) and cystic fibrosis related diabetes (CFRD) have increased in prevalence. In the absence of consensus on the management of IGT, the role of dietary intake, specifically carbohydrate quality, requires consideration.

AIMS

The aims of this study were to: 1) determine nutritional quality of dietary intake at an adult CF clinic and compare this to the Australian Dietary Guidelines 2) explore relationships between dietary intake, including glycaemic index (GI) and glycaemic load (GL), and glucose response variables using continuous glucose monitoring (CGM).

METHODS

Adults attending a Sydney hospital were recruited to undergo CGM for five-seven days and record dietary intake using a food record over the CGM period. The relationship between variables of dietary intake, including GI and GL and variables of glycaemic response, including mean amplitude of glycaemic excursions (MAGE), percentage of time in hyperglycaemic and euglycaemic range, were determined.

RESULTS

Eighteen participants completed the study with 87 full days of dietary and CGM data. Dietary intake was higher than recommendations in the Australian Dietary Guidelines in relation to grains and protein foods and only slightly higher in saturated fat. Bivariate correlations showed dietary GI was significantly positively associated with percentage of time in hyperglycaemic range. Dietary GL was significantly associated with SD, MAGE and percentage of time in euglycaemic range on CGM. Results remained significant when controlled for energy intake in partial correlation analyses.

CONCLUSIONS

This study suggests GI and GL may be important dietary factors influencing glucose metabolism in CF. Further studies exploring low GI or GL diets as a dietary intervention in CF are the next step.

Dietary interventions for managing glucose abnormalities in cystic fibrosis: a systematic review protocol

BACKGROUND

Glucose abnormalities in cystic fibrosis (CF) are common, but there is limited evidence to guide their dietary management. Progressive impaired glucose tolerance eventually leads to cystic fibrosis-related diabetes (CFRD), the most prevalent complication of CF, which is associated with increased morbidity and mortality. Optimising glycaemic control improves clinical status and reduces mortality; insulin therapy is the primary means of controlling glycaemia in CFRD, but its role in managing pre-diabetes is less clear. CF dietary therapy requires a high calorie diet due to increased energy expenditure and malabsorption, but this energy-dense diet is typically high in fat and sugar, and high sugar intakes often result in hyperglycaemia in individuals who have impaired glucose handling. Current guidelines for the dietary management of glucose abnormalities in CF are based on clinical consensus rather than empirical evidence. A systematic review conducted in 2012 on the effects of low glycaemic index dietary intervention in CF concluded that there is a dearth of evidence in this area. This review will update the systematic review by Balzer et al. in 2012 and will broaden the scope of their review to include any type of dietary intervention for managing glucose abnormalities in CF.

METHODS

Quantitative studies of dietary interventions to manage glucose abnormalities in individuals aged over 5 years with CF and glucose abnormalities will be reviewed. No limits will be placed on language or study design. The comparator will be standard CF dietary therapy (energy dense, high-fat diet) in addition to insulin therapy for individuals with CFRD. Electronic databases will be searched for completed quantitative studies published in peer-review journals that focus on dietary interventions for managing glucose abnormalities in CF. Searches will be conducted from 2000 up to the present day to reflect the evolving improvements in CF management. No restrictions will be placed on study design or language. Duration of the dietary intervention must be a minimum of 2 months and only interventions in out-patient or community settings will be included. Studies must report on dietary intervention, glycaemic control, anthropometry and lung function. Evidence will be assessed for heterogeneity and a narrative review or meta-analysis conducted as appropriate.

DISCUSSION

This systematic review will elucidate current knowledge of the effects of dietary interventions for managing glucose abnormalities in the vulnerable CF clinical population.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration number: CRD42018085569 www.crd.york.ac.uk/prospero/.

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.

Influence of macrolides, nutritional support and respiratory therapies in diabetes and normal glucose tolerance in cystic fibrosis. A retrospective analysis of a cohort of adult and younger patients

AIM

The development of cystic fibrosis related diabetes is associated with increased morbidity and mortality, worse nutritional status and lung function decline. It is known that patients with cystic fibrosis have a chronic inflammation status and that β pancreatic cells are very sensitive to oxidative stress. So these inflammatory mediators could contribute to the onset of progressive pancreatic fibrosis and, hence, to impair glucose metabolism. So, it could be hypothesized that the treatment with macrolides would protect and preserve β-cell function by decreasing pro-inflammatory cytokines and free oxidative radicals.

METHODS

We retrospectively analyzed a cohort of 64 patients affected of cystic fibrosis, older than 14 years, by using the first pathological 2-h oral glucose tolerance test; peripheral insulin resistance was calculated using the homeostasis model assessment for insulin resistance (HOMA - IR) and pancreatic β-cell function was estimated according to Wareham. The influence of macrolides, microbiological colonization, nutritional support and related clinical parameters were analyzed.

RESULTS

Comparing CFRD without FPG and NGT, and after adjustment for microbial colonization, the significance of the use of macrolides was lost (p=0.1), as a risk or protective factor for any of the studied groups. Non-significative associations were found in the use of macrolides, inhaled corticosteroids and nutritional support therapies within the different disorders of carbohydrate metabolism.

CONCLUSIONS

The anti-inflammatory and immunomodulating effect of macrolides did not seem to affect the β cell function or insulin resistance in patients with cystic fibrosis. The use of inhaled corticosteroids or nutritional supplements have not any influence in the carbohydrate metabolism. Further prospective studies are needed to analyze a potential protective role of macrolides in the development of carbohydrate metabolism alterations in cystic fibrosis.

Cystic fibrosis related diabetes--a new perspective on the optimal management of postprandial glycemia

As the average life expectancy of patients with cystic fibrosis (CF) improves, the long term co-morbidities assume increasing importance. CF related diabetes (CFRD) has adverse effects on both nutrition and pulmonary function, and is associated with increased mortality. Abnormalities of glucose metabolism in CF represent a continuum; however the predominant abnormality is postprandial, not pre-prandial, glycemia. Insulin is currently recommended as the treatment of choice for CFRD, but its use is associated with a number of limitations, including hypoglycemia. Both the rate of gastric emptying and the consequent release of the 'incretin' hormones, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like-peptide-1 (GLP-1), from the gut are important determinants of overall glycemic control, particularly postprandial glycemia. Both are abnormal in conditions associated with exocrine pancreatic insufficiency. Incretin based therapies that have the capacity to slow gastric emptying and/or modulate the release of 'incretin' hormones, are now used widely in type 2 diabetes (T2D). This paper explores the determinants of glycemic control in CF, with a particular focus on the roles of gastric emptying and 'incretin' hormones, providing a rationale for the use of therapies that delay gastric emptying, including incretin mimetics, to minimize postprandial glycemia and improve nutritional status.

Fat-soluble vitamin deficiency in children and adolescents with cystic fibrosis

AIMS

Determine the prevalence of fat-soluble vitamin deficiency in children with cystic fibrosis (CF) aged ≤18 years in New South Wales (NSW), Australia, from 2007 to 2010.

METHODS

A retrospective analysis of fat-soluble vitamin levels in children aged ≤18 years who lived in NSW and attended any of the three paediatric CF centres from 2007 to 2010. An audit of demographic and clinical data during the first vitamin level measurement of the study period was performed.

RESULTS

Deficiency of one or more fat-soluble vitamins was present in 240/530 children (45%) on their first vitamin level test in the study period. The prevalence of vitamins D and E deficiency fell from 22.11% in 2007 to 15.54% in 2010, and 20.22% to 13.89%, respectively. The prevalence of vitamin A deficiency increased from 11.17% to 13.13%. Low vitamin K was present in 29% in 2007, and prevalence of prolonged prothrombin time increased from 19.21% to 22.62%. Fat-soluble vitamin deficiency is present in 10%-35% of children with pancreatic insufficiency, but only a very small proportion of children who are pancreatic-sufficient.

CONCLUSIONS

This is one of few studies of fat-soluble vitamin deficiency in children with CF in Australia. Fat-soluble vitamin testing is essential to identify deficiency in pancreatic-insufficient children who may be non-compliant to supplementation or require a higher supplement dose, and pancreatic-sufficient children who may be progressing to insufficiency. Testing of vitamin K-dependent factors needs consideration. Further studies are needed to monitor rates of vitamin deficiency in the CF community.

The impact of dysglycaemia on bone mineral accrual in young people with cystic fibrosis

OBJECTIVE

The effect of dysglycaemia on bone mineral density (BMD) has not been studied in young people with CF. We examined factors associated with BMD in a tertiary paediatric CF clinic.

DESIGN

Retrospective, clinic-based study at The Children's Hospital at Westmead, Sydney.

PATIENTS

Young people with CF aged ≤ 18 years.

MEASUREMENTS

Bone mineral density was measured by dual-energy X-ray absorptiometry; main outcome measures were total body (TB), lumbar spine (LS) and femoral neck (FN) BMD and bone mineral content (BMC), and LS volumetric BMD (vBMD), reported as z scores for height. Dysglycaemia, based on oral glucose tolerance test, was defined as CF-related diabetes (CFRD) or impaired glucose tolerance (IGT).

RESULTS

Overall, 14 of 81 (17%) had CFRD, 6 (7%) IGT and 61 (76%) normal glucose tolerance (NGT). Mean age was 14.9 ± 2.4 years and mean height z score -0.68 ± 1.39. Osteopenic (z score ≤-2) TB, LS or FN BMD was present in 30 of 81 (37%), BMC in 42 (52%) and vBMD in 10 (5%). Across the three groups, there were differences in LS vBMD (CFRD, -0.67 ± 0.76; IGT, -0.52 ± 0.76; NGT, -0.05 ± 1.39; P = 0.04), LS BMD (P < 0.01), LS BMC (P = 0.01) and TB BMD (P = 0.01). In multivariate linear regression, LS BMC was associated with dysglycaemia (β = 0.56; 95% CI, 0.00-1.13; P = 0.05) and approached significance for FEV(1) (β = 0.01; 95% CI, 0.00-0.02; P = 0.06).

CONCLUSIONS

Dysglycaemia is associated with reduced bone mass accrual in youth with CF, in addition to recognized factors such as abnormal lung function, poor nutritional status and disease severity. Bone health assessment is essential in youth with CF.

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

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

Ion channelopathies in endocrinology: recent genetic findings and pathophysiological insights

Ion channels serve diverse cellular functions, mainly in cell signal transduction. In endocrine cells, these channels play a major role in hormonal secretion, Ca(2+)-mediated cell signaling, transepithelial transport, cell motility and growth, volume regulation and cellular ionic content and acidification of lysosomal compartments. Ion channel dysfunction can cause endocrine disorders or endocrine-related manifestations, such as pseudohypoaldosteronism type 1, Liddle syndrome, Bartter syndrome, persistent hyperinsulinemic hypoglycemia of infancy, neonatal diabetes mellitus, cystic fibrosis, Dent's disease, hypomagnesemia with secondary hypocalcemia, nephrogenic diabetes insipidus and, the most recently genetically identified channelopathy, thyrotoxic hypokalemic periodic paralysis. This review briefly recapitulates the membrane action potential in endocrine cells and offers a short overview of known endocrine channelopathies with focus on recent progress regarding the pathophysiological mechanisms and functional genetic defects.

Cystic fibrosis related diabetes (CFRD)--the end stage of progressive insulin deficiency

In cystic fibrosis, gradual pancreatic destruction causes progressive insulin deficiency, culminating in cystic fibrosis related diabetes (CFRD). As a consequence of insulin deficiency, elevated glucose levels can be detected (well before the diagnosis of CFRD), by continuous ambulatory subcutaneous interstitial fluid glucose monitoring or 30-min sampled oral glucose tolerance test (OGTT). Current diagnostic criteria for CFRD (based on 0 and 120-min OGTT blood glucose levels) were originally designed to forecast microvascular disease in type 2 diabetes, rather than CF-specific outcomes such as declining weight or lung function. In CF, decline in either weight or lung function predicts early mortality. Both may precede the diagnosis of CFRD by several years. Insulin, a potent anabolic hormone, is recommended treatment for CFRD, but use in earlier stages of insulin deficiency is not established. Conventional dosing (with four or more insulin injections per day) is burdensome and carries substantial risk of hypoglycemia. However, recent uncontrolled trials suggest that once-daily injection of intermediate or long-acting insulin improves weight and lung function, with minimal hypoglycemia risk, in CFRD and also in early insulin deficiency. It is plausible that insulin may be of greater benefit to respiratory function when given prior to the diagnosis of CFRD, after which structural lung disease may be irreversible. It is also plausible that early insulin treatment may prolong the lifespan of the remaining insulin-secreting β-cells. Randomized controlled trials are now needed to determine whether or not current clinical practice should be altered toward the earlier commencement of insulin in CF.