Abnormal glucose tolerance in cystic fibrosis: why should patients be screened?

Nutrition for Patients With Cystic Fibrosis

Cystic fibrosis (CF) is the most frequent, lethal genetic disorder among northern Europeans. The etiology of this autosomal recessive disease is known to be a defect in the cAMP activation of chloride (Cl-) channels in secretory cells in many organs of the body. Although this defect usually leads to severe lung disease, many of these patients also have nutritional deficiencies. Nutrition is one of the key components in the management of CF. Patients are at high risk for malnutrition, which may result in accelerated progression of the disease and increased morbidity. This review will discuss nutrition recommendations for calories, protein, vitamins and minerals, and enteral and parenteral nutrition support practices.

Diabetes in cystic fibrosis: multicenter screening results based on current guidelines

BACKGROUND

Published estimates on age-dependent frequency of diabetes in cystic fibrosis (CF) vary widely, and are based mostly on older data. However, CF treatment and prevention of comorbidities changed over recent years. In many studies, definition of cystic fibrosis-related diabetes (CFRD) is not in line with current guideline recommendations. Therefore, we evaluated age-dependent occurrence of glucose abnormalities and associated risk factors in CF patients who participated in a multicenter screening program using oral glucose tolerance tests (OGTT).

METHODS

Between 2001 and 2010, 43 specialized CF centers from Germany and Austria serially performed 5,179 standardized OGTTs in 1,658 clinically stable, non-pregnant CF patients with no prior steroid medication or lung transplantation. Age-dependent occurrence of impaired fasting glucose (IFG), impaired glucose tolerance (IGT), IFG+IGT, one (DGT) or two consecutive (CFRD) diabetic OGTTs was analyzed, using Kaplan Meier curves. Cox proportional-hazards models were created to elucidate the influence of sex or underweight.

RESULTS

At baseline/last OGTT, median age was 15.9 years/18.2 years and 30.6%/31.8% of patients were underweight. 25% of patients showed IFG at age 14.3 years; IGT at age 16.3 years; IFG+IGT combined at age 17.7 years. DGT was observed in 25% of patients at age 22.6 years; CFRD at age 34.5 years. Females had a 3.54 [95% CI 1.23-10.18] times higher risk for CFRD; risk for DGT was 2.21 [1.22-3.98] times higher. Underweight was a risk factor for IGT (HR [95% CI]: 1.38 [1.11-1.71]) and IFG+IGT (1.43 [1.11-1.83]), and in males also for DGT (1.49 [1.09-2.04]).

CONCLUSIONS/SIGNIFICANCE

If confirmation of diabetes by a second test is required, as recommended in current guidelines, age at CFRD diagnosis was higher compared to most previous studies. However, known risk factors for glucose abnormalities in CF were confirmed. Confirmation of diabetic OGT by a repeat test is important for a consistent diagnosis of CFRD.

[Diabetes mellitus: clinical presentation and differential diagnosis of hyperglycemia in childhood and adolescence]

Diabetes mellitus is one of the most common chronic diseases in childhood. Despite being a clinical and etiopathogenically heterogeneous disorder, type 1 autoimmune diabetes accounts for more than 95% of cases in children. Recent advances have meant that a growing number of patients have been assigned to other subtypes of diabetes. In such cases, the correct diagnosis is facilitated by the fact that many of these rare causes of diabetes are associated with specific clinical syndromes or may present at a certain age. Many of them are also subsidiaries of molecular diagnosis. The aim of this review is to update the current knowledge in this field of pediatric diabetes, in an attempt to determine the most accurate diagnosis and its implications on appropriate treatment and prognosis.

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.

Isolation, motivation and balance: living with type 1 or cystic fibrosis-related diabetes

AIMS AND OBJECTIVES

To explore patients' responses to developing and managing cystic fibrosis-related diabetes and to contrast their views with those of individuals with type 1 diabetes mellitus.

BACKGROUND

The incidence of diabetes among people with cystic fibrosis has increased with improvement in life expectancy. However, little is known about how patients respond to and manage cystic fibrosis-related diabetes, and how this compares with people living with type 1 diabetes mellitus.

DESIGN

Qualitative research was undertaken in order to fully explore meanings and views.

METHODS

Semi-structured telephone or face-to-face interviews were conducted with patients who had cystic fibrosis-related diabetes or type 1 diabetes mellitus, during which, they discussed diagnosis and management of diabetes. Framework analysis was employed to identify themes and to consider similarities and differences between the two groups.

RESULTS

Eleven cystic fibrosis-related diabetes and 12 type 1 diabetes mellitus patients were interviewed in 2006. Patients with cystic fibrosis-related diabetes described their diabetes diagnosis as a progression of their primary illness, management of which was important owing to the benefits it brought to their cystic fibrosis. Those with type 1 diabetes mellitus were more likely to report feeling psychologically low because of diabetes and to list long-term complications as a key factor motivating self-management. Both groups struggled to balance the demands of diabetes with other life and health obligations, and experienced isolation because of diabetes. Conclusions. Variation in perceptions recalled during interviews stemmed from diabetes being part of an existing life-threatening chronic illness in people with cystic fibrosis-related diabetes. Similarities and differences in attitudes and management practices were found, with less urgency regarding glucose monitoring and fewer information resources available for those with cystic fibrosis-related diabetes.

RELEVANCE TO CLINICAL PRACTICE

Both groups need support for optimal diabetes management and access to appropriate resources outside specialist clinics. Web-based technologies could prove useful for those with cystic fibrosis-related diabetes as face-to-face interaction may be prevented owing to the risk of cross-infection.

A teenage girl with cystic fibrosis-related diabetes, diabetic ketoacidosis, and cerebral edema

Diabetic ketoacidosis (DKA) is a potentially life-threatening complication of diabetes, most commonly associated with type 1 diabetes. Here, we report the case of a 17-yr-old girl with cystic fibrosis and a prior diagnosis of cystic fibrosis-related diabetes (CFRD) who presented with DKA in the setting of insulin omission and glucocorticoid use. During the course of treatment for DKA, her neurologic status declined and head computerized tomography confirmed cerebral edema. Recognition of DKA and cerebral edema allowed for timely treatment, and the patient recovered without sequelae. This is the first report of DKA complicated by cerebral edema that is attributable to CFRD.

Diabetes mellitus in patients with cystic fibrosis

Cystic fibrosis-related diabetes (CFRD) is the principal extra-pulmonary complication of cystic fibrosis, occurring in 15-30% of adult cystic fibrosis patients. The number of cystic fibrosis patients who develop diabetes is increasing in parallel with increases in life expectancy. The aim of this study was to review the physiopathology, clinical presentation, diagnosis and treatment of CFRD. A bibliographic search of the Medline and Latin American and Caribbean Health Sciences Literature databases was made. Articles were selected from among those published in the last twenty years. Insulin deficiency, caused by reduced beta-cell mass, is the main etiologic mechanism, although insulin resistance also plays a role. Presenting features of type 1 and type 2 diabetes, CFRD typically affects individuals of approximately 20 years of age. It can also be accompanied by fasting, non-fasting or intermittent hyperglycemia. Glucose intolerance is associated with worsening of nutritional status, increased morbidity, decreased survival and reduced pulmonary function. Microvascular complications are always present, although macrovascular complications are rarely seen. An oral glucose tolerance test is recommended annually for patients > or = 10 years of age and for any patients presenting unexplained weight loss or symptoms of diabetes. Patients hospitalized with severe diseases should also be screened. If fasting hyperglycemia persists for more than 48 h, insulin therapy is recommended. Insulin administration remains the treatment of choice for diabetes and fasting hyperglycemia. Calories should not be restricted, and patients with CFRD should be managed by a multidisciplinary team.

Continuous glucose monitoring system in the screening of early glucose derangements in children and adolescents with cystic fibrosis

BACKGROUND

In cystic fibrosis (CF), diabetes mellitus (DM) is associated with progression of pulmonary disease and nutritional impairment.

AIM

To compare oral glucose tolerance test (OGTT) and continuous glucose monitoring system (CGMS) in patients with CF with early glucose derangements.

PATIENTS AND METHODS

Thirty-two patients with CF (5-20 years) with intermediate glucose values > 7.7 mmol/l during OGTT received a CGMS registration. Patients were classified into those with normal glucose tolerance (NGT), impaired glucose tolerance (IGT) and DM, according to glucose values at 120 min of OGTT and during CGMS. Furthermore BMI z-scores, forced expiratory volume in 1 second (FEV1%), number of respiratory infections/year, enzyme supplementation, and HbA1c were evaluated.

RESULTS

OGTT and CGMS derangements were in agreement in 43.7% of the patients. BMI z-scores, FEV1%, number of respiratory infections/ year, enzyme supplementation, and HbA1c did not differ among the three groups. HbA1c, correlated positively with 120 min OGTT (r = 0.34; p = 0.059), CGMS area (r = 0.35; p = 0.048) and the number of respiratory infections, and negatively with FEV1%.

CONCLUSIONS

Intermediate glucose values during OGTT should be considered as a screening test in patients with CF. CGMS can be useful in studying the early occurrence of glucose derangements in selected patients.

Increased glucose excursion in cystic fibrosis and its association with a worse clinical status

BACKGROUND

Abnormal glucose tolerance is a frequent co-morbidity in cystic fibrosis patients (CF), and is associated with a worse prognosis. The objectives are to investigate (a) the relative contribution of insulinopenia and insulin resistance (IR) for glucose tolerance and (b) the association between various glucose parameters and CF clinical status.

METHODS

Oral glucose tolerance tests were performed in 114 consecutive CF patients not known to be diabetic as well as 14 controls similar for age and BMI.

RESULTS

Abnormal glucose tolerance was found in 40% of patients with CF: 28% had impaired glucose tolerance (IGT) and 12% had new cystic fibrosis related diabetes (CFRD). Compared to control subjects, all CF patients were characterized by an increased glucose excursion (AUC). While reduced early insulin release characterised CF, IGT and CFRD patients also present IR thus both mechanisms significantly contribute to glucose tolerance abnormalities. Increased glucose AUC and reduced early insulin release but not glucose tolerance categories were associated with a reduced pulmonary function (FEV(1)).

CONCLUSION

In CF, early insulin secretion defect but also IR contribute to glucose intolerance. Early in the course of the disease, increased glucose AUC and reduced early insulin secretion are more closely associated with a worse clinical status than conventional glucose tolerance categories.

Cystic fibrosis transmembrane conductance regulator deficiency exacerbates islet cell dysfunction after beta-cell injury

The cause of cystic fibrosis-related diabetes (CFRD) remains unknown, but cystic fibrosis transmembrane conductance regulator (CFTR) mutations contribute directly to multiple aspects of the cystic fibrosis phenotype. We hypothesized that susceptibility to islet dysfunction in cystic fibrosis is determined by the lack of functional CFTR. To address this, glycemia was assessed in CFTR null (CFTR(-/-)), C57BL/6J, and FVB/NJ mice after streptozotocin (STZ)-induced beta-cell injury. Fasting blood glucose levels were similar among age-matched non-STZ-administered animals, but they were significantly higher in CFTR(-/-) mice 4 weeks after STZ administration (288.4 +/- 97.4, 168.4 +/- 35.9, and 188.0 +/- 42.3 mg/dl for CFTR(-/-), C57BL/6J, and FVB/NJ, respectively; P < 0.05). After intraperitoneal glucose administration, elevated blood glucose levels were also observed in STZ-administered CFTR(-/-) mice. STZ reduced islets among all strains; however, only CFTR(-/-) mice demonstrated a negative correlation between islet number and fasting blood glucose (P = 0.02). To determine whether a second alteration associated with cystic fibrosis (i.e., airway inflammation) could impact glucose control, animals were challenged with Aspergillus fumigatus. The A. fumigatus-sensitized CFTR(-/-) mice demonstrated similar fasting and stimulated glucose responses in comparison to nonsensitized animals. These studies suggest metabolic derangements in CFRD originate from an islet dysfunction inherent to the CFTR(-/-) state.

Hyperglycaemia and insulinopenia in a neonate with cystic fibrosis

Abnormal glucose tolerance is a frequent late complication of cystic fibrosis (CF), but the prevalence of CF-related diabetes mellitus (CFRD) in children less than 10 y old is less than 2%. The youngest child with CFRD reported to date was 6 mo of age. Insulinopenia is the primary cause of abnormal glucose tolerance/CFRD, but it is unknown whether it may begin in the neonatal period. We describe a case of a neonate with CF who presented with hyperglycaemia in the diabetic range and marked insulinopenia. Insulinopenia and impaired glucose tolerance were permanent findings at 6 and 15 mo of age.

CONCLUSION

This case suggests that abnormal glucose tolerance/diabetes may occur much earlier in the course of CF, even during neonatal age. Careful follow-up and further studies in CF infants could reveal that the real incidence of glucose intolerance and diabetes in this age group has been underestimated.

Diabetes: a major co-morbidity of cystic fibrosis

Cystic fibrosis-related diabetes (CFRD) is a frequent complication of cystic fibrosis, its prevalence increases with age of patient and is close to 30% at the age of 30 years. As life expectancy greatly increases, the number of cystic fibrosis patients developing diabetes will increase too. CFRD shares some features with type 1 and type 2 diabetes, initial phase is characterised by postprandial hyperglycaemia followed by a progression toward insulin deficiency. Insulin deficiency is an essential factor in the development of diabetes with an additional contribution of insulin resistance. Systematic screening with an oral glucose tolerance test is recommended from the age of 14 years because clinical signs of CFRD are often confused with signs of pulmonary infection and CFRD occurrence is associated with weight and pulmonary function deterioration. In observational studies CFRD diagnosis is associated with a significant increase in mortality, while treatment allow correction of weight and lung deterioration suggesting that CFRD has a significant impact on CF evolution. Microvascular complications are recognised, although paucity of data does not permit a clear description of their natural history. Annual screening for microvascular complication is recommended. There is no evidence by now that CF patients develop macrovascular complications. The only recommended pharmacological treatment is insulin therapy.