🏥 ORAL GLUCOSE TOLERANCE TEST IN THE HOSPITAL 🏥 (4.18.18)
A Practical Approach to Glucose Abnormalities in Cystic FibrosisCystic fibrosis is a common genetic condition and abnormal glucose handling leading to cystic fibrosis-related diabetes CFRD is a frequent comorbidity. CFRD is mainly thought to be the result of progressive pancreatic damage resulting in beta cell dysfunction and loss of insulin secretion. Whilst Oral Boldenone pl Tolerance Testing is still recommended for diagnosing CFRD, the relationship between glucose abnormalities and adverse outcomes in CF is complex and occurs at stages of dysglycaemia oral glucose tolerance test who protocol prior to diagnosis of diabetes by World Health Organisation criteria. Insulin remains the mainstay of treatment of CF-related glucose abnormalities but the timing of insulin commencement, optimum insulin regime and targets of glycaemic control are not clear. These complexities nebido testosteron depot compounded by oral glucose tolerance test who protocol issues with nutritional status, need for enteral feeding, steroid use and high disease burden on CF patients.
Cystic fibrosis is a common genetic condition and abnormal glucose handling leading to cystic fibrosis-related diabetes CFRD is a frequent comorbidity. CFRD is mainly thought to be the result of progressive pancreatic damage resulting in beta cell dysfunction and loss of insulin secretion. Whilst Oral Glucose Tolerance Testing is still recommended for diagnosing CFRD, the relationship between glucose abnormalities and adverse outcomes in CF is complex and occurs at stages of dysglycaemia occurring prior to diagnosis of diabetes by World Health Organisation criteria.
Insulin remains the mainstay of treatment of CF-related glucose abnormalities but the timing of insulin commencement, optimum insulin regime and targets of glycaemic control are not clear. These complexities are compounded by common issues with nutritional status, need for enteral feeding, steroid use and high disease burden on CF patients. Cystic fibrosis CF is a common life-limiting autosomal recessive condition with the highest prevalence in populations with Northern European ancestry.
The disease is caused by gene mutation causing defective function of a chloride channel—the cystic fibrosis transmembrane conductance regulator CFTR —which is vital for mucociliary clearance in the airways [ 1 ]. Cystic fibrosis impacts several organ systems including the liver, skin sweat glands and pancreas, but its classical impact on morbidity and mortality is via bronchiectasis, airways obstruction and progression to respiratory failure.
Abnormalities of glucose metabolism are an important co-morbidity of CF. Classically, progressive loss of beta cell function in CF leads to abnormal glucose levels and progression to cystic fibrosis-related diabetes CFRD [ 2 — 4 ]. The development of glucose abnormalities is recognised to herald a clear increase in morbidity and mortality in patients with CF, leading to a focus on identifying and controlling disordered glucose metabolism in CF [ 5 , 6 ].
The management of CFRD is complex and importantly it differs significantly from that of type 1 and type 2 diabetes. Management of CFRD requires a multidisciplinary approach to attempt to ensure the best possible clinical outcome, whilst minimising treatment-associated adverse events.
This article explores the pathophysiology, diagnosis and clinical impact of glucose abnormalities in CF and discusses the approach to treatment of this challenging problem. This article is based on previously conducted studies and does not involve any new studies of human or animal subjects performed by any of the authors. CFRD is primarily characterisable as a defect of insulin release resulting from the secretions blocking pancreatic ducts, autodigestion, oxidative stress and destructive fibrotic pancreatic disease that ultimately destroys islet cell function [ 2 — 4 ].
Pancreatic beta cell function and first phase insulin secretion have been shown to be reduced in CFRD when compared to normal glucose tolerance NGT patients with CF where no difference is observed in insulin resistance [ 7 ]. Patients with CF also have more rapid small bowel glucose absorption further exacerbating postprandial glucose excursions [ 8 ]. Patients with CF have also been shown to have decreased GLP-1 activity compared to normal controls, which may contribute to glucose abnormalities [ 9 ].
CF is a complex multisystem disease, and multiple defects in nutritional status and metabolism also contribute to observed glucose abnormalities. CFRD is clinically and pathophysiologically distinct from either type 1 or type 2 diabetes. It appears to develop earlier in female than male patients [ 10 ]. Ketoacidosis is rare but can occur if CFRD goes untreated or in the presence of significant intercurrent infection [ 12 ]. As the age at which CFRD and type 1 diabetes usually present overlaps, it is important to remember that patients with CF can also develop type 1 diabetes.
The recent history of CF has been one of greatly improved survival. Improvements in physiotherapy and drugs to clear mucus from the lungs and aggressive treatment of infection, combined with pancreatic exocrine supplements and enhanced nutrition, have all contributed to significant improvements in morbidity and mortality in patients with cystic fibrosis.
In males, the standardised PYLL decreased from In Canada, median survival age increased from First, it is a time-consuming investigation for patients and staff to perform. Furthermore, the OGGT was primarily developed as a way of predicting risk of microvascular and macrovascular complications of hyperglycaemia, and as such it does not necessarily predict the risks and complications associated with dysglycaemia in CF.
The response of measured glucose to an oral glucose challenge is especially variable in patients with CF. Crucially, early CFRD is classically characterised by postprandial glucose excursions secondary to loss of first phase insulin. Whilst HbA1c is now accepted as a diagnostic tool within the field of diabetes, it is difficult to interpret as a diagnostic test for CFRD. Relatively brief periods of postprandial hypoglycaemia with low normal pre-meal glucose levels have the potential to lead to reassuringly normal HbA1c values.
CFRD is additionally associated with a lower than normal red cell lifespan, which could reduce diagnostic utility [ 22 ]. If HbA1c is to have utility, lower levels will need to be considered as clinically important. A systematic review of screening tests for CFRD agreed that the sensitivity of HbA1c is too low to recommended it as a diagnostic test [ 24 ]. Adapted from ADA guidelines [ 16 ]. Abnormalities of glucose metabolism have a clear association with morbidity and mortality in CF patients.
It is less clear whether hyperglycaemia or insulin deficiency have a causal relationship with poor outcomes or are simply markers of more advanced or complicated disease. Worsening lung function is clearly associated with glucose abnormalities, and a decline in pulmonary function appears to be related to the severity of glucose intolerance and insulin deficiency [ 18 ].
Patients with CFRD have more episodes of infection and have higher rates of colonisation with important pathogenic organisms such as BurkholderiaCepacia and Aspergillus suggesting impaired immunity [ 29 ].
It has been suggested that an association between poor lung function and dysglycaemia may be more important in females [ 30 ]. In a UK registry study of patients with CF the presence of diabetes was an independent risk factor for death hazard ratio 1.
These consistent associations between insulinopenicdysglycaemia and adverse outcome suggest correcting glucose abnormalities with insulin or insulin secretagogues may confer benefit.
Whilst the the primary focus in CFRD is on lung function and nutritional status, it is important to remember that, as with all types of diabetes mellitus, effective screening for microvascular complications is required. Compared to patients with type 1 diabetes patients with CFRD have a similar incidence of microvascular disease with a lower prevalence of retinopathy and a higher prevalence of microalbuminuria [ 33 ].
Screening for microvascular complications is likely to increase in importance with increasing longevity of patients with CFRD. Unlike other forms of diabetes where control of glucose is primarily to prevent microvascular and macrovascular complications, the main goal in CFRD is prevention and improvement of declining respiratory function and nutritional status.
Several small non-randomised studies, retrospective reviews and case series have suggested a benefit of insulin in both reducing the decline of lung function and weight loss.
These studies use a variety of insulins with various levels of glycaemia and clinical triggers for patient selection [ 34 — 37 ]. We have reported retrospective, observational data from our unit, which suggest that introducing insulin at the stage of impaired glucose tolerance seems to ameliorate loss of lung function and increase weight [ 38 ].
One open-label randomised study attempted to assess the impact on clinical outcomes of preprandial insulin treatment compared to repaglinide and placebo in patients with CFRD but no fasting hyperglycaemia. It was felt that the short duration of the study made it unlikely that changes in lung function would have been detected [ 39 ].
Hypoglycaemia is an obvious potential risk when using insulin in CF patients. Hypoglycaemia can be observed in CF patients even before they have treatment for dysglycaemia, perhaps suggesting a mismatch between the increased late insulin secretion and rapid carbohydrate absorption [ 40 ]; 6.
Hypoglycaemia was also found to be associated with a significantly higher rate of readmission or death over the 3. This is a higher rate of hypoglycaemia than that previously reported in the general population of inpatients with diabetes [ 42 ]. Hypoglycaemia in CF patients treated with insulin has also been associated with high levels of loss of awareness of hypoglycaemia, which may reflect loss of glucagon response or high exposure to hypoglycaemic range glucose [ 38 ].
It is therefore important to balance the potential benefit of insulin use in CF with the burden and harm of hypoglycaemia. Continuous subcutaneous insulin infusion CSII by pump would seem in theory to offer significant potential advantages of flexibility and avoidance of hypoglycaemia, which could be of particular benefit in CFRD.
There have been some small studies of insulin secretagogues showing reductions in glucose levels in CFRD; however none have shown significant benefit to important outcomes of lung function or weight [ 39 , 44 ].
We do not presently recommended the use of insulin secretagogues in CFRD. We favour the use of the prandial insulin bolus initially in the majority of cases for reasons of flexibility and as postprandial hyperglycaemia is usually the primary abnormality.
We add basal insulin when fasting glucose becomes abnormal or bolus requirements become high. There is insufficient evidence to be dogmatic about what glycaemic target should be aimed for in patients with CFRD. This seems a reasonable goal, and patients should be encouraged to perform CBG testing regularly including postprandially if possible. Existing and required dose of insulin may double during acute illness and steroid therapy.
Nutritional status is of great importance in CF patients who have both increased resting energy expenditure and increased loss of calories through malabsorption and in whom cachexia is known to worsen outcome [ 46 ]. Optimising nutritional status is therefore an important goal, which has been shown to improve the ability to undertake normal daily activities [ 47 ].
To maintain high calorific intake enteral tube feeding ETF is commonly utilised and is thought to improve outcome [ 48 ]. Our experience suggests that liaisoning between the diabetes team and specialist dieticians is crucial when planning ETF. Variation in the timing and tolerability of ETF can make choosing the optimum insulin to maximise energy conservation from the feed challenging.
Choice of insulin should be made by matching the duration of insulin action to the agreed enteral feeding regimen. Use of steroids usually prednisolone or methylprednisolone has been common in patients with CF and can cause transient hyperglycaemia or worsen glucose control in existing CFRD.
There is little evidence to guide management of hyperglycaemia related to steroid use in the general population let alone in CFRD. National guidelines suggest enhanced CBG monitoring and the use of insulin to correct hyperglycaemia [ 51 ]. We recommend CBG monitoring of fasting and postprandial glucose in all CF patients started on steroids.
Glucose abnormalities related to CF pose unique challenges to both diabetes and respiratory teams. The close associations between worsening dysglycaemia and poor outcome suggest benefit from insulin replacement therapy, but the time to start treatment and desired CBG levels remain controversial.
Insulin therapy has significant potential to cause harm—especially by inducing hypoglycaemia. At present we recommend a pragmatic multidisciplinary approach to managing this complex area.
We suggest insulin use targeting postprandial glucose excursions, initiated when risks of declining lung function and nutritional status are high. We use postprandial CBG measurements to guide insulin dosing along with pre-prandial and fasting CBG measurement to guard against hypoglycaemia. Further data would be welcomed on the optimum timing of insulin initiation and on the glycaemic targets that would best prevent decline in lung function.
No funding or sponsorship was received for this study or publication of this article. All named authors meet the International Committee of Medical Journal Editors ICMJE criteria for authorship for this manuscript, take responsibility for the integrity of the work as a whole, and have given final approval for the version to be published.
Jones and Christopher A. Sainsbury have nothing to disclose. To view enhanced content for this article go to http: National Center for Biotechnology Information , U. Journal List Diabetes Ther v. Published online Oct Received Sep Abstract Cystic fibrosis is a common genetic condition and abnormal glucose handling leading to cystic fibrosis-related diabetes CFRD is a frequent comorbidity.
Cystic fibrosis, Cystic fibrosis-related diabetes, Diabetes, Hypoglycaemia. Introduction Cystic fibrosis CF is a common life-limiting autosomal recessive condition with the highest prevalence in populations with Northern European ancestry.
Compliance with Ethics Guidelines This article is based on previously conducted studies and does not involve any new studies of human or animal subjects performed by any of the authors. Pathophysiology CFRD is primarily characterisable as a defect of insulin release resulting from the secretions blocking pancreatic ducts, autodigestion, oxidative stress and destructive fibrotic pancreatic disease that ultimately destroys islet cell function [ 2 — 4 ].
A: Protocols. Oral Glucose Tolerance Test (OGTT). Oral Glucose Tolerance Test ( OGTT). Indication: Diagnosis of Diabetes Mellitus. Methods and Criteria for. Number of deaths attributable to high blood glucose males Evidence-based national diabetes guidelines/protocols/standards Oral glucose tolerance test. ○. There are three versions of the oral glucose tolerance test: the Avoid going to the bathroom just before the procedure because you may need Overview.