Epidemiology, pathophysiology, and prognostic implications of cystic fibrosis-related diabetes: a technical review

A novel case of diabetic muscle necrosis in a patient with cystic fibrosis-related diabetes

Cystic fibrosis is a recessive autosomal disease caused by mutations in the cystic fibrosis transmembrane conductance regulator gene. Cystic fibrosis-related diabetes (CFRD) is a common comorbidity of cystic fibrosis. Diabetic myonecrosis is a rare self-limited complication of poorly controlled diabetes mellitus that commonly presents with acute, intense pain and swelling of lower extremities and responds well to conservative management. We report the first case of diabetic myonecrosis in a patient with CFRD.

Insulin secretion improves in cystic fibrosis following ivacaftor correction of CFTR: a small pilot study

OBJECTIVE

To determine whether the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) is involved in human insulin secretion by assessing the metabolic impact of the new CFTR corrector-ivacaftor.

METHODS

This open-label pilot study was conducted in CF patients with the G551D mutation given new prescriptions for ivacaftor. At baseline and 4 wk after daily ivacaftor therapy, intravenous glucose tolerance tests (IVGTT) and oral glucose tolerance tests (OGTT) were performed.

RESULTS

Five patients aged 6-52 were studied. After 1 month on ivacaftor, the insulin response to oral glucose improved by 66-178% in all subjects except one with long-standing diabetes. OGTT glucose levels were not lower in the two individuals with diabetes or the two with normal glucose tolerance (NGT), but the glucose tolerance category in the subject with impaired glucose tolerance (IGT) improved to NGT after treatment. In response to intravenous glucose, the only patient whose acute insulin secretion did not improve had newly diagnosed, untreated CFRD. The others improved by 51-346%. Acute insulin secretion was partially restored in two subjects with no measurable acute insulin response at baseline, including the one with IGT and the one with long-standing diabetes.

CONCLUSIONS

This small pilot study suggests there is a direct role of CFTR in human insulin secretion. Larger, long-term longitudinal studies are necessary to determine whether early initiation of CFTR correction, particularly in young children with CF who have not yet lost considerable β-cell mass, will delay or prevent development of diabetes in this high-risk population.

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.

Optic disc swelling and vision loss in a patient with cystic fibrosis and diabetes

Advances in cystic fibrosis management have significantly improved life expectancy in these patients. However, we are now faced with a growing number of long-term extrapulmonary consequences of this disease, including ophthalmic complications of diabetes in cystic fibrosis patients. We present a unique report that documents a case of diabetic papillopathy progressing to nonarteritic anterior ischemic optic neuropathy resulting in vision loss in a patient with CF and diabetes. It highlights the potentially devastating consequences of longstanding diabetes in CF patients.

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.

Diabetes mellitus secondary to pancreatic diseases (Type 3c)--are we neglecting an important disease?

Type 3c diabetes mellitus (T3cDM) is a clinically relevant condition with a prevalence of 5-10% among all diabetic subjects in Western populations. Its prevalence and clinical importance have been underestimated and underappreciated so far. In contrast to the management of type 1 or type 2 diabetes, the endocrinopathy in T3cDM is very complex and complicated by additional present comorbidities such as maldigestion and concommitant qualitative malnutrition. The failure to correctly diagnose T3cDM leads to failure to implement an appropriate medical therapy of these patients. Physicians should screen for important and easily reversable pathological conditions such as exocrine insufficiency, lack of fat-soluble vitamins (especially vitamin D) and impairment of fat hydrolysis and incretin secretion which are found very commonly in T3cDM. Since most patients with T3cDM suffer from chronic pancreatitis, physicians must additionally be aware of the elevated risk of pancreatic cancer in this subset of patients.

Comparison of cystic fibrosis-related diabetes with type 1 diabetes based on a German/Austrian Pediatric Diabetes Registry

OBJECTIVE

The prevalence of cystic fibrosis-related diabetes (CFRD) has increased with improved life expectancy of patients. Clinical and care characteristics were compared with type 1 diabetes mellitus (T1DM) in a multicenter analysis of pediatric data.

RESEARCH DESIGN AND METHODS

Auxological and treatment data from 47,227 patients aged younger than 21 years with CFRD or T1DM in the German/Austrian Diabetes Prospective Documentation Initiative registry were analyzed by multivariable mixed regression modeling.

RESULTS

Diabetes onset (mean [interquartile range]) occurred later in individuals with CFRD (14.5 [11.8-16.3] years) than in individuals with T1DM (8.5 [4.9-11.8] years), with female preponderance in CFRD (59.1% vs. 47.5%; P < 0.01). CFRD patients had lower BMI standard deviation scores (-0.85 [-1.59 to -0.12] vs. +0.52 [-0.10 to +1.16]; P < 0.01) and lower HbA(1c) (6.87% vs. 7.97%; P < 0.01). Self-monitoring of blood glucose was more frequent in patients with T1DM (4.5 vs. 3.5; P < 0.01); 72% of CFRD patients received insulin. In insulin-treated patients, insulin dosage adjusted for age, sex, and diabetes duration differed significantly (T1DM: 0.79 IE per kilogram of body weight; CFRD: 0.83 IE per kilogram of body weight). Use of short-acting and long-acting insulin analogs was significantly more frequent in T1DM (47% vs. 39% and 37% vs. 28%; both P < 0.05). Metabolic control in CFRD patients without insulin was better compared with CFRD on insulin (HbA(1c): 6.00 vs. 7.12; P < 0.01), but duration of disease was significantly shorter (0.8 years [0.1-2.4] compared with 2.4 years [0.6-4.6]). There was no significant difference for BMI standard deviations scores between CFRD patients with or without insulin treatment.

CONCLUSIONS

Pediatric patients with CFRD show clear auxological and metabolic differences from those with T1DM, with different treatment choices.

ZnT8 antibodies in patients with cystic fibrosis: an expression of secondary beta-cell damage?

Cystic Fibrosis-Related Diabetes (CFRD) is caused by a severe insulin deficiency with associated different degrees of insulin resistance. Data concerning the potential impact of autoimmunity are conflicting. Ninety subjects with cystic fibrosis (CF) were tested for glucose tolerance and autoantibodies against insulin (IAA), glutamic acid decarboxylase (GADA), protein tyrosine phosphatase (IA2) and zinc transporter 8 (Znt8A). Eighty-three subjects showed a normal glucose tolerance (92.2%), 6 subjects (6.6%) impaired glucose tolerance and 1 subject (1.1%) newly diagnosed CFRD. Four subjects were found positive for both IAA and GADA (4.4%), one subject (1.1%) for both IA2 and GADA, and one subject (1.1%) for isolated GADA. Three subjects (3.3%) showed isolated ZnT8A positivity. ZnT8A positivity in CF patients is uncommon and not associated with other autoantibodies. ZnT8A may not represent a specific indicator of a primary autoimmune beta-cell destruction, but possibly the expression of a secondary damage of the pancreatic islets with autoantigen release.

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.

Cystic fibrosis: what to expect now in the early adult years

As a testimony to advances in patient care, more individuals with cystic fibrosis are surviving into their adult years than ever before. The clinical epidemiology of this complex multi-organ disease is evolving and has changed dramatically over the past two to three decades. This article discusses the emergence of chronic disease-related co-morbidities such as CF-related diabetes, chronic kidney disease, bone disease, arthropathy, and depression. It also provides an overview of the many challenges confronted by adult CF care providers.

Transplanting the adolescent cystic fibrosis patient: can we do it?

Bilateral lung transplantation remains a treatment for end-stage cystic fibrosis (CF) lung disease when there is no further medical or surgical treatment available. The aim of lung transplantation is to improve patient life expectancy. The consensus view that lung transplantation extends life in children has been challenged. However, challengers have faced alternative explanations of their finding and it is largely accepted that lung transplantation in the adolescent patient population is an important treatment modality. The goal of this article is to address these concerns and assist with developing creative approaches to this known challenging subset of patients. The main focus of this article will be to discuss the looming question: what existing evidence or best practice insights could improve bilateral lung transplantation outcomes for adolescent patients with end-stage CF?

Abnormal endocrine pancreas function at birth in cystic fibrosis ferrets

Diabetes is a common comorbidity in cystic fibrosis (CF) that worsens prognosis. The lack of an animal model for CF-related diabetes (CFRD) has made it difficult to dissect how the onset of pancreatic pathology influences the emergence of CFRD. We evaluated the structure and function of the neonatal CF endocrine pancreas using a new CFTR-knockout ferret model. Although CF kits are born with only mild exocrine pancreas disease, progressive exocrine and endocrine pancreatic loss during the first months of life was associated with pancreatic inflammation, spontaneous hyperglycemia, and glucose intolerance. Interestingly, prior to major exocrine pancreas disease, CF kits demonstrated significant abnormalities in blood glucose and insulin regulation, including diminished first-phase and accentuated peak insulin secretion in response to glucose, elevated peak glucose levels following glucose challenge, and variably elevated insulin and C-peptide levels in the nonfasted state. Although there was no difference in lobular insulin and glucagon expression between genotypes at birth, significant alterations in the frequencies of small and large islets were observed. Newborn cultured CF islets demonstrated dysregulated glucose-dependent insulin secretion in comparison to controls, suggesting intrinsic abnormalities in CF islets. These findings demonstrate that early abnormalities exist in the regulation of insulin secretion by the CF endocrine pancreas.

Glucose tolerance during pulmonary exacerbations in children with cystic fibrosis

Background

Patients with Cystic Fibrosis (CF) are relatively insulinopenic and are at risk of diabetes, especially during times of stress. There is a paucity of data in the literature describing glucose tolerance during CF pulmonary exacerbations. We hypothesised that glucose tolerance would be worse during pulmonary exacerbations in children with CF than during clinical stability.

Methods

Patients with CF, 10 years or older, admitted with a pulmonary exacerbation underwent an OGTT within 48 hours of admission. A repeat OGTT was performed 4 to 6 weeks post discharge when the patients were well.

Results

Nine patients completed the study. Four patients were found to have normal glucose tolerance, 3 with impaired and 2 with CF related diabetes during the exacerbation. Mean change in 2-hour glucose was 1.1 mmol (SD = 0.77). At the follow up OGTT, 8 of 9 (89%) remained within their respective glucose tolerance status groupings.

Conclusion

The findings of this study show that there is little difference in glucose tolerance during CF exacerbations compared to clinical stability in the majority of patients.

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.

Newborn screening and renal disease: where we have been; where we are now; where we are going

Newborn screening (NBS) has rapidly changed since its origins in the 1960s. Beginning with a single condition, then a handful in the 1990 s, NBS has expanded in the past decade to allow the detection of many disorders of amino-acid, organic-acid, and fatty-acid metabolism. These conditions often present with recurrent acute attacks of metabolic acidosis, hypoglycemia, liver failure, and hyperammonemia that may be prevented with initiation of early treatment. Renal disease is an important component of these disorders and is a frequent source of morbidity. Hemodialysis is often required for hyperammonemia in the organic acidemias and urea-cycle disorders. Rhabdomyolysis with renal failure is a frequent complication in fatty-acid oxidation disorders. Newer screening methods are under investigation to detect lysosomal storage diseases, primary immunodeficiencies, and primary renal disorders. These advances will present many challenges to nephrologists and pediatricians with respect to closely monitoring and caring for children with such disorders.

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.

Pancreatogenic diabetes: special considerations for management

BACKGROUND/AIMS

Pancreatogenic, or type 3c, diabetes (T3cDM) occurs due to inherited or acquired pancreatic disease or resection. Although similar to the more prevalent type 1 and type 2 diabetes, pancreatogenic diabetes has a unique pattern of hormonal and metabolic characteristics and a high incidence of pancreatic carcinoma in the majority of patients with T3cDM. Despite these differences, no guidelines for therapy have been described.

METHODS

Published studies on the prevalence, pathophysiology, and cancer associations of T3cDM were reviewed. The recent studies on the protective role and mechanism of metformin therapy as both an anti-diabetic and anti-neoplastic agent were reviewed, and studies on the cancer risk of other anti-diabetic drugs were surveyed.

RESULTS

T3cDM accounts for 5-10% of Western diabetic populations and is associated with mild to severe disease. Hepatic insulin resistance is characteristic of T3cDM and is caused by deficiencies of both insulin and pancreatic polypeptide. 75% of T3cDM is due to chronic pancreatitis, which carries a high risk for pancreatic carcinoma. Insulin and insulin secretagogue treatment increases the risk of malignancy, whereas metformin therapy reduces it. Pancreatic exocrine insufficiency associated with T3cDM contributes to nutritional deficiencies and the development of metabolic bone disease.

CONCLUSIONS

Until consensus recommendations are reached, the glycemic treatment of T3cDM should avoid insulin and insulin secretagogues if possible. Metformin should be the first line of therapy, and continued if insulin treatment must be added for adequate glucose control. Pancreatic enzyme therapy should be added to prevent secondary nutritional and metabolic complications. and IAP.