Management of cystic fibrosis-related diabetes

Understanding the Pancreatic Islet Microenvironment in Cystic Fibrosis and the Extrinsic Pathways Leading to Cystic Fibrosis Related Diabetes

Cystic fibrosis (CF) is an autosomal recessive chronic condition effecting approximately 70 000 to 100 000 people globally and is caused by a loss-of-function mutation in the CF transmembrane conductance regulator. Through improvements in clinical care, life expectancy in CF has increased considerably associated with rising incidence of secondary complications including CF-related diabetes (CFRD). CFRD is believed to result from β-cell loss as well as insufficient insulin secretion due to β-cell dysfunction, but the underlying pathophysiology is not yet fully understood. Here we review the morphological and cellular changes in addition to the architectural remodelling of the pancreatic exocrine and endocrine compartments in CF and CFRD pancreas. We consider also potential underlying proinflammatory signalling pathways impacting on endocrine and specifically β-cell function, concluding that further research focused on these mechanisms may uncover novel therapeutic targets enabling restoration of normal insulin secretion.

Continuous Glucose Monitoring as a Valuable Tool in the Early Detection of Diabetes Related to Cystic Fibrosis

Aims: We evaluated the impact of cystic fibrosis-related diabetes (CFRD) on lung disease and nutritional status. Study Design: The retrospective cohort study evaluated the subjects' medical records from 2004 to 2019. All participants older than 10 years diagnosed by a 30-minutely sampled OGTT formed OGTT-CFRD subgroup. The participants diagnosed with continuous glucose monitoring (CGM) (at least two peaks above 11.1 mmol/l and more than 10% of recorded time above 7.8 mmol/l) formed a CFRD-CGM subgroup. The participants without CFRD formed a non-CFRD group. The longitudinal follow-up was made 2 years before and 3 years after insulin therapy initiation. Results: Of 144 participants included, aged 10-55 years (44% males), 28 (19.4%) had CFRD. The HbA1c was significantly lower in the CGM-CFRD in comparison to the OGTT-CFRD subgroup (5.9 ± 0.62 and 7.3 ± 1.7% respectfully; p = 0.04). Subjects with CFRD were malnourished in comparison to non-CFRD, with significant improvements with insulin replacement therapy in regard to BMI Z-score (-1.4 ± 1.3 vs. -0.5 ± 1.2%, p = 0.04) and pulmonary exacerbation score (p = 0.02). In OGTT-CFRD subgroup there is an increase in FEV1 (62.7 ± 26.3 to 65.1 ± 21.7%, p = 0.7) and decrease in FVC (from 76.4 ± 24.2 to 71.2 ± 20%, p = 0.003) from diagnosis to second year of follow-up. In CGM-CFRD subgroup there was a decrease in FEV1 (from 58.2 ± 28.2 to 52.8 ± 25.9%, p = 0.2) and FVC-values (from 72.4 ± 26.5 to 67.4 ± 29.1%, p = 0.08).Chronic Pseudomonas aeruginosa infection was more prevalent in the CFRD group (p = 0.003). Conclusion: Continuous glucose monitoring is a useful tool for insight of glucose impairment and diagnosis of CFRD. Early recognition of CFRD and therapeutic intervention has favorable effects on clinical course of the disease.

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.

Cystic fibrosis-related diabetes is caused by islet loss and inflammation

Cystic fibrosis-related (CF-related) diabetes (CFRD) is an increasingly common and devastating comorbidity of CF, affecting approximately 35% of adults with CF. However, the underlying causes of CFRD are unclear. Here, we examined cystic fibrosis transmembrane conductance regulator (CFTR) islet expression and whether the CFTR participates in islet endocrine cell function using murine models of β cell CFTR deletion and normal and CF human pancreas and islets. Specific deletion of CFTR from murine β cells did not affect β cell function. In human islets, CFTR mRNA was minimally expressed, and CFTR protein and electrical activity were not detected. Isolated CF/CFRD islets demonstrated appropriate insulin and glucagon secretion, with few changes in key islet-regulatory transcripts. Furthermore, approximately 65% of β cell area was lost in CF donors, compounded by pancreatic remodeling and immune infiltration of the islet. These results indicate that CFRD is caused by β cell loss and intraislet inflammation in the setting of a complex pleiotropic disease and not by intrinsic islet dysfunction from CFTR mutation.

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

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

A small volatile bacterial molecule triggers mitochondrial dysfunction in murine skeletal muscle

Mitochondria integrate distinct signals that reflect specific threats to the host, including infection, tissue damage, and metabolic dysfunction; and play a key role in insulin resistance. We have found that the Pseudomonas aeruginosa quorum sensing infochemical, 2-amino acetophenone (2-AA), produced during acute and chronic infection in human tissues, including in the lungs of cystic fibrosis (CF) patients, acts as an interkingdom immunomodulatory signal that facilitates pathogen persistence, and host tolerance to infection. Transcriptome results have led to the hypothesis that 2-AA causes further harm to the host by triggering mitochondrial dysfunction in skeletal muscle. As normal skeletal muscle function is essential to survival, and is compromised in many chronic illnesses, including infections and CF-associated muscle wasting, we here determine the global effects of 2-AA on skeletal muscle using high-resolution magic-angle-spinning (HRMAS), proton (¹H) nuclear magnetic resonance (NMR) metabolomics, in vivo³¹P NMR, whole-genome expression analysis and functional studies. Our results show that 2-AA when injected into mice, induced a biological signature of insulin resistance as determined by ¹H NMR analysis-, and dramatically altered insulin signaling, glucose transport, and mitochondrial function. Genes including Glut4, IRS1, PPAR-γ, PGC1 and Sirt1 were downregulated, whereas uncoupling protein UCP3 was up-regulated, in accordance with mitochondrial dysfunction. Although 2-AA did not alter high-energy phosphates or pH by in vivo³¹P NMR analysis, it significantly reduced the rate of ATP synthesis. This affect was corroborated by results demonstrating down-regulation of the expression of genes involved in energy production and muscle function, and was further validated by muscle function studies. Together, these results further demonstrate that 2-AA, acts as a mediator of interkingdom modulation, and likely effects insulin resistance associated with a molecular signature of mitochondrial dysfunction in skeletal muscle. Reduced energy production and mitochondrial dysfunctional may further favor infection, and be an important step in the establishment of chronic and persistent infections.

New insights into cystic fibrosis-related diabetes in children

Cystic fibrosis-related diabetes (CFRD) is the most common complication of cystic fibrosis. It is associated with significantly increased morbidity and mortality in adults and children. Adolescents with cystic fibrosis have a much higher prevalence of diabetes than any other similar age population. Glucose abnormalities that precede diabetes are even more common, especially in children younger than 10 years. The pathophysiology of glucose metabolic abnormalities is poorly understood, but insulin insufficiency is clearly the main component. Findings from animal studies have provided insight into the pathophysiology of CFRD, and imply that carbohydrate metabolic abnormalities might begin at much younger ages than was previously thought in patients with cystic fibrosis, and might be related to the basic cystic fibrosis chloride channel defect. In this Review we explore present knowledge of CFRD in children and adolescents, and new data that indicate that the pathophysiology of CFRD begins in very young patients.

Update on cystic fibrosis-related diabetes

Diabetes mellitus has emerged as a common comorbidity in cystic fibrosis and is considered a clinical entity (cystic fibrosis-related diabetes, CFRD) distinct from that of type 1 diabetes (T1DM) and type 2 diabetes (T2DM). The relevance of this diagnosis extends not only from its imposition of additional medical burden but its association with worse health outcomes in individuals with CF. This paper will review the 2010 U.S. and other international guidelines for screening and treating CFRD. It will highlight newer data regarding early glucose and insulin secretion defects, mechanisms linking CFRD to worse outcomes, and recent advances in T2DM that may provide insights for CFRD; insulin secretion will be reviewed as background for these recent developments.

Cystic fibrosis-related diabetes in adults: inpatient management of 121 patients during 410 admissions

BACKGROUND

With improved longevity, cystic fibrosis (CF)-related diabetes (CFRD) has emerged as the most common nonpulmonary complication of CF. Patients with CFRD are frequently admitted to the hospital with infections and deterioration of pulmonary function, during which time glycemic control might have an impact on pulmonary function, recovery from infection, and survival.

METHODS AND RESULTS

In an attempt to share our insight into inpatient management of CFRD, this article summarizes the experience of our inpatient glucose management team with hospital management of 121 adult CFRD patients who were hospitalized on 410 occasions at the University of Colorado Hospital between January 2009 and September 2011. This is a retrospective chart review descriptive study of inpatient management of CFRD in our center. Our cohort includes CFRD patients treated with basal and mealtime insulin through multiple daily injections or continuous subcutaneous insulin infusion (CSII), as well as patients receiving steroids or enteral nutrition, which adds complexity to the management of CFRD during hospitalization.

CONCLUSIONS

Multiple hospitalizations and intensive inpatient management of CF are integral elements of treatment. Inpatient therapy for CFRD requires a customized approach that is uniquely different from that of type 1 or type 2 diabetes. Our experience highlights clinical circumstances such as irregular food intake, high dose steroid therapy, and supplemental tube feeding. For many patients, it is possible to continue CSII therapy during hospitalization through a combination of mutual trust between the patient and hospital staff and oversight provided by the glucose management team.

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.

Neutrophil unsaturated fatty acid release by GM-CSF is impaired in cystic fibrosis

Dysregulated inflammation in cystic fibrosis (CF) is attributed to an altered production of inflammatory mediators derived from polyunsaturated lipids. In comparison to the arachidonic acid (AA) cascade, little is known about the modulation of docosahexaenoic acid (DHA) membrane release. We compared data on neutrophil DHA- and AA- release from both control (CT) and patients with CF using [³H]AA or [¹⁴C]DHA as a markers for, respectively, AA and DHA- release. Granulocyte-macrophage-colony stimulating factor stimulated DHA release from CT, but not CF, neutrophils. Comparison showed that both [¹⁴C]DHA and [³H]AA liberated after stimulation was higher in CT than in CF neutrophils. Since bioactive mediators derived from DHA are resolving factors and those derived from AA are both pro- and anti- inflammatory, these results suggest that CF is associated with a reduction of the release of PUFA-precursors of lipooxygenated resolving mediators. This leads to the hypothesis that defects in the resolving factors production could contribute to the inflammatory dysregulated processes in CF. Furthermore, the methodology used may help to improve knowledge on the regulation and resolution of inflammation.

Oral glucose tolerance testing in children with cystic fibrosis

BACKGROUND

Cystic fibrosis (CF) related diabetes is the most common comorbidity in persons with CF. International Society for Pediatric and Adolescent Diabetes (ISPAD) guidelines recommend annual oral glucose tolerance testing (OGTT) screening starting at age 10. The OGTT might be recommended in younger children if, as in adults, it provided clinically relevant prognostic information. A database review was performed to determine whether OGTT findings in children with CF predict subsequent clinical course.

METHODS

A retrospective matched-pair cohort study was based on OGTTs performed during 1998-2003. Children aged 6-9 were classified as having normal glucose tolerance (NGT) or abnormal glucose tolerance (AGT). Children with AGT were matched by age and gender to those with NGT. Clinical status was assessed at baseline and 5 yr later. In a separate investigation, diabetes and prior AGT status of children aged 10-18 were used to assess predictions derived from the cohort study.

RESULTS

In 1998-2003, 39 of 94 children had AGT. Of these, 31 had sufficient follow-up data to be included. Both at baseline and 5 yr later there was no significant difference in height, weight, body mass index (BMI) or lung function between AGT and NGT. Diabetes developed in 13 AGT (42%) and one NGT (3%) [odds ratio (OR) 11, p = 0.0009]. Age of diabetes onset was 12 ± 1 yr in boys and 11 ± 1 yr in girls, compared to approximately 23 yr in the general CF population. Fifteen current children age 10-18 who had AGT before age 10 have diabetes, close to the prediction of 19.

CONCLUSIONS

AGT in children with CF age 6-9 yr identifies those at high risk for progression to early onset diabetes.

Diabetes due to exocrine pancreatic disease--a review of patients attending a hospital-based diabetes clinic

BACKGROUND

Diabetes secondary to underlying exocrine pancreatic disease is a specific, but heterogeneous, type of diabetes mellitus. Studies such as UKPDS and DCTT excluded patients with pancreatic diabetes, so there is a paucity of evidence regarding best clinical practice in this group.

AIM

To characterize the clinical features of patients with diabetes secondary to underlying pancreatic disease attending general diabetes clinics in a single hospital.

DESIGN AND METHODS

A cross-sectional observational cohort study, identifying patients with pancreatic diabetes from clinic letters and medical notes at the University Hospital of Wales, Cardiff, UK.

RESULTS

The notes of 38 patients with pancreatic diabetes were reviewed. Of these, six had pancreatic malignancy and the remainder had a range of benign disorders. The majority (29/38) had diabetes diagnosed at or shortly after the pancreatic diagnosis was made. There was a lack of consistency regarding initial hypoglycaemic therapy, with metformin alone being the most common initial therapy, but with 30/38 taking insulin within 12 months of diagnosis. Similarly, a broad range of insulin regimens were employed with twice daily pre-mixed insulin being most prevalent. Sixty-three percent of patients were prescribed lipid lowering therapy and 42% were taking anti-hypertensives. Glycaemic control, as estimated by the latest HbA1C, was no different in patients with pancreatic diabetes compared to the general clinic population and there were no reports of severe hypoglycaemia.

CONCLUSION

There is great variability in how patients with pancreatic diabetes are currently managed. Future clinical trials should specifically address this group.

Abnormal glucose tolerance in children with cystic fibrosis: the predictive role of continuous glucose monitoring system

A long pre-diabetic phase of abnormal glucose tolerance is described in subjects with cystic fibrosis (CF) since childhood.

OBJECTIVE

The aims of the study were to compare oral glucose tolerance test (OGTT) and continuous glucose monitoring system (CGMS) in the diagnosis of altered glucose metabolism, and to longitudinally evaluate the role of CGMS in predicting glucose metabolism deterioration in children with CF.

METHODS

Seventeen children with CF and 14 controls were enrolled (mean age 13.3+/-3.0 years). All subjects underwent OGTT and CGMS registration. On the basis of OGTT, children were classified as normal glucose tolerance, impaired glucose tolerance (IGT), IGT plus at least one glucose value above 200 mg/dl at intermediate OGTT points (IGT+200) and CF-related diabetes (CFRD). HbA1c, glucose area under the curve, insulin sensitivity, and insulinogenic and disposition indexes were also considered. Subjects with CF underwent another OGTT after 2.5 years.

RESULTS

Baseline OGTT revealed 3/17 (7.6%) children with CF with at least one glucose value above 200 mg/dl (1 CFRD and 2 IGT+200), while CGMS revealed 6/17 (35.3%) children with glucose excursions above 200 mg/dl (P=0.010). None of the controls showed glucose over 200 mg/dl either at OGTT or at CGMS. At the 2.5-year follow-up OGTT, all the six subjects who had diabetic glucose excursion (i.e. >200 mg/dl) at baseline CGMS presented IGT+200 or CFRD. In logistic regression analysis, CGMS diabetic excursion was the strongest predictor of IGT+200 and CFRD (P<0.001).

CONCLUSIONS

CGMS could be a useful tool to predict glucose metabolism derangements in children affected by CF.

Early glucose abnormalities in cystic fibrosis are preceded by poor weight gain

OBJECTIVE

Progressive beta-cell loss causes catabolism in cystic fibrosis. Existing diagnostic criteria for diabetes were based on microvascular complications rather than on cystic fibrosis-specific outcomes. We aimed to relate glycemic status in cystic fibrosis to weight and lung function changes.

RESEARCH DESIGN AND METHODS

We determined peak blood glucose (BG(max)) during oral glucose tolerance tests (OGTTs) with samples every 30 min for 33 consecutive children (aged 10.2-18 years). Twenty-five also agreed to undergo continuous glucose monitoring (CGM) (Medtronic). Outcome measures were change in weight standard deviation score (wtSDS), percent forced expiratory volume in 1 s (%FEV1), and percent forced vital capacity (%FVC) in the year preceding the OGTT.

RESULTS

Declining wtSDS and %FVC were associated with higher BG(max) (both P = 0.02) and with CGM time >7.8 mmol/l (P = 0.006 and P = 0.02, respectively) but not with BG(120 min). A decline in %FEV1 was related to CGM time >7.8 mmol/l (P = 0.02). Using receiver operating characteristic (ROC) analysis to determine optimal glycemic cutoffs, CGM time above 7.8 mmol/l > or =4.5% detected declining wtSDS with 89% sensitivity and 86% specificity (area under the ROC curve 0.89, P = 0.003). BG(max) > or =8.2 mmol/l gave 87% sensitivity and 70% specificity (0.76, P = 0.02). BG(120 min) did not detect declining wtSDS (0.59, P = 0.41). After exclusion of two patients with BG(120 min) > or =11.1 mmol/l, the decline in wtSDS was worse if BG(max) was > or =8.2 mmol/l (-0.3 +/- 0.4 vs. 0.0 +/- 0.4 for BG(max) <8.2 mmol/l, P = 0.04) or if CGM time above 7.8 mmol/l was > or =4.5% (-0.3 +/- 0.4 vs. 0.1 +/- 0.2 for time <4.5%, P = 0.01).

CONCLUSIONS

BG(max) > or =8.2 mmol/l on an OGTT and CGM time above 7.8 mmol/l > or =4.5% are associated with declining wtSDS and lung function in the preceding 12 months.

Nutritional considerations in patients with cystic fibrosis

Nutritional status is strongly associated with pulmonary function and survival in cystic fibrosis patients. Attainment of a normal growth pattern in childhood and maintenance of adequate nutritional status in adulthood represent major goals of multidisciplinary cystic fibrosis centers. International guidelines on energy intake requirements, pancreatic enzyme-replacement therapy and fat-soluble vitamin supplementation are of utmost importance in daily practice. The present review summarizes the most up-to-date information on early nutritional management in newly diagnosed patients and evaluates the benefits of aggressive nutritional support, assessment of nutritional status, recommendations for nutrition-related management in pancreatic-insufficient patients and the possible therapeutic impact of fat intake modulation upon inflammatory status.

Cystic fibrosis related diabetes

Diabetes is a frequent complication seen in cystic fibrosis patients as they reach adulthood. Cystic fibrosis related diabetes (CFRD) is distinguished as a separate entity with features that include progressive loss of islet beta cell mass and insulin deficiency, as well as insulin resistance. Abnormalities in glucose tolerance may be detectable for many years prior to the development of overt diabetes. Therefore oral glucose tolerance testing is the preferred screening method for the identification of those patients at the highest risk for progression to diabetes. Progression to diabetes has been linked to poor outcomes in CF including loss of pulmonary function and increased mortality among females. Given the role that insulin deficiency plays in CFRD, insulin replacement therapy remains the only recommended intervention. In the absence of definitive supportive data, the use of oral antidiabetic agents is not considered standard therapy and needs further study. As with other forms of diabetes, CFRD patients also experience microvascular complications and should be periodically evaluated for manifestations.

Symposium 6: Young people, artificial nutrition and transitional care The nutritional challenges of the young adult with cystic fibrosis: transition

Cystic fibrosis (CF) is a complex multisystem disorder affecting mainly the gastrointestinal tract and respiratory system. Intestinal malabsorption occurs in approximately 90% of patients. In the past, malnutrition was an inevitable consequence of disease progression, leading to poor growth, impaired respiratory muscle function, decreased exercise tolerance and immunological impairment. A positive association between body weight and height and survival has been widely reported. The energy requirements of patients with CF vary widely and generally increase with age and disease severity. For many young adults requirements will be 120–150% of the age-related estimated average requirement. To meet these energy needs patients are encouraged to eat a high-fat high-energy diet with appropriate pancreatic enzyme supplements. Many patients are unable to achieve an adequate intake as a result of a variety of factors including chronic poor appetite, infection-related anorexia, gastro-oesophageal reflux and abdominal pain. Oral energy supplements and enteral tube feeding are widely used. Nutritional support has been shown to improve nutritional status and stabilise or slow the rate of decline in lung function. With such emphasis on nutritional intake and nutritional status throughout life, poor adherence to therapies and issues relating to body image are emerging. The median survival of patients with CF is increasing. CF is now considered a life-limiting disease of adulthood rather than a terminal childhood illness. With increased longevity new challenges are emerging that include the transition of young adults with CF to adult services, CF-related diabetes, disordered eating, osteoporosis, liver disease and transplantation.

Cystic fibrosis

Cystic fibrosis is the most common lethal genetic disease in white populations. The outlook for patients with the disease has improved steadily over many years, largely as a result of earlier diagnosis, more aggressive therapy, and provision of care in specialised centres. Researchers now have a more complete understanding of the molecular-biological defect that underlies cystic fibrosis, which is leading to new approaches to treatment. One of these treatments, hypertonic saline, is already in use, whereas others are in advanced stages of development. We review clinical care for cystic fibrosis and discuss recent advances in the understanding of its pathogenesis, implementation of screening of neonates, and development of therapies aimed at treating the basic defect.

[Continuous glucose monitoring system in the screening of glucose disorders in cystic fibrosis]

BACKGROUND

Diabetes mellitus (DM) is an increasing complication of cystic fibrosis (CF). It is associated with enhance morbidity. Continuous glucose monitoring system (CGMS) could detect glucose disorders earlier than other screening tests usually used.

AIMS

To compare oral glucose tolerance test (OGTT), HbA(1c) and CGMS in patients with CF and recent disorders of glucose homeostasis and to analyse changes in nutritional status and/or pulmonary function.

PATIENTS AND METHODS

Thirteen patients with CF (11-22 years, 7 males) were studied using OGTT, HbA(1c) and CGMS. All of them had newly diagnosed glucose disturbances. They were not receiving steroid therapy or had an underlying illness. In all subjects we compared: HbA(1c) levels (%), fasting and 2-hours glucose OGTT (mg/dl) and glucose CGMS values (overall, fasting, 2-hours post mean-meals and excursions >140mg/dl at any time). Furthermore, body mass index, forced expiratory volume in the first second (%) and forced vital capacity (%) were evaluated in the previous year and at the time of the study. We also analysed exocrine pancreatic function and CF-mutation.

RESULTS

Mean age at diagnosis of glucose disturbance was 16.4 years. All patients had insufficient exocrine pancreatic function and 11/13 presented DeltaF508 CF-mutation. Only one patient was diagnosed with DM using OGGT and 7/13 (53.8%) with CGMS. A total 77% of patients had poor nutritional status and/or pulmonary function at time of diagnosing the glucose disorder. Only 4 patients had abnormal HbA(1c) levels.

CONCLUSIONS

CGMS allows a better detection of glucose disorders than OGTT. Glucose homeostasis abnormalities are associated with a decrease in nutritional status and/or pulmonary function. HbA(1c) does not aid in the early diagnose of glucose disorders.