The use of exenatide in severely burned pediatric patients

Exendin-4 Exacerbates Burn-Induced Mortality in Mice by Switching to Th2 Response

INTRODUCTION

To determine if Exendin-4 could be a therapeutic agent for burn-induced hyperglycemia.

MATERIALS AND METHODS

Male Balb/c mice received a bolus of Exendin-4 intraperitoneally immediately after 15% total body surface area scald injury. Tail glucose levels were recorded and T-cell functions were analyzed at 4 h and 24 h postburn (pb). Pancreatic pathology was observed consecutively. The secretions of cytokines were detected in serum, spleen, and lung. Apoptosis of splenic CD3+ T-cells was examined by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling and flow cytometry.

RESULTS

Although Exendin-4 could attenuate burn-induced hyperglycemia in mice at 4 h pb, it accelerated their survival dose dependently with progressive depletion of splenocyte number. T-cell function underwent two-phasic changes following Exendin-4 treatment. Compared to placebo mice, T-cell from Exendin-4-treated mice was manifested with increased proliferation, while decreased IL-2 secretion and lower ratio of IL-4/IFN-γ at 4 h pb. However, at 24 h pb, it showed decreased proliferation, while increased IL-2 secretion and higher ratio of IL-4/IFN-γ. Exendin-4 could elicit higher circulating IL-6 and IL-10 levels at 4 h pb, which were pronounced in the lung at 24 h pb. In the meanwhile, severe inflammation could be found in the pancreas. At 24 h pb, the numbers of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling or caspase-3 positive cells and the apoptosis of CD3+ T-cells were significantly increased in the spleens of Exendin-4 mice relative to placebo mice.

CONCLUSIONS

These data support a pathogenic role of Exendin-4 signaling during thermal injury, warning against its clinical application in acute insults.

Glucose Metabolism in Burns-What Happens?

Severe burns represent an important challenge for patients and medical teams. They lead to profound metabolic alterations, trigger a systemic inflammatory response, crush the immune defense, impair the function of the heart, lungs, kidneys, liver, etc. The metabolism is shifted towards a hypermetabolic state, and this situation might persist for years after the burn, having deleterious consequences for the patient's health. Severely burned patients lack energy substrates and react in order to produce and maintain augmented levels of glucose, which is the fuel "ready to use" by cells. In this paper, we discuss biological substances that induce a hyperglycemic response, concur to insulin resistance, and determine cell disturbance after a severe burn. We also focus on the most effective agents that provide pharmacological modulations of the changes in glucose metabolism.

Debate on Insulin vs Non-insulin Use in the Hospital Setting-Is It Time to Revise the Guidelines for the Management of Inpatient Diabetes?

PURPOSE OF REVIEW

Hyperglycemia contributes to a significant increase in morbidity, mortality, and healthcare costs in the hospital. Professional associations recommend insulin as the mainstay of diabetes therapy in the inpatient setting. The standard of care basal-bolus insulin regimen is a labor-intensive approach associated with a significant risk of iatrogenic hypoglycemia. This review summarizes recent evidence from observational studies and clinical trials suggesting that not all patients require treatment with complex insulin regimens.

RECENT FINDINGS

Evidence from clinical trials shows that incretin-based agents are effective in appropriately selected hospitalized patients and may be a safe alternative to complicated insulin regimens. Observational studies also show that older agents (i.e., metformin and sulfonylureas) are commonly used in the hospital, but there are few carefully designed studies addressing their efficacy. Therapy with dipeptidyl peptidase-4 (DPP-4) inhibitors, alone or in combination with basal insulin, may effectively control glucose levels in patients with mild to moderate hyperglycemia. Further studies with glucagon-like peptide-1 (GLP-1) receptor analogs and older oral agents are needed to confirm their safety in the hospital.

Noninsulin medication therapy for hospitalized patients with diabetes mellitus

PURPOSE

Published evidence regarding the role of noninsulin antidiabetic therapies in glycemic management of hospitalized patients with diabetes mellitus is reviewed.

SUMMARY

The American Diabetes Association recommends against the routine use of noninsulin antidiabetic therapies during hospitalization and supports insulin use instead. There are significant risks associated with insulin therapy, including hypoglycemia, and use of alternative therapies may be considered in hospitalized patients. A MEDLINE literature search was conducted to find articles on studies evaluating the use of noninsulin antidiabetic therapies in the inpatient setting; all full-text English-language publications presenting observational and randomized clinical trial data on the topic of interest were considered for inclusion in the review, with 9 publications selected for review. The majority of the reviewed research focused on incretin-based therapies, and favorable safety and efficacy outcomes were reported with the use of dipeptidyl peptidase-4 (DPP-4) inhibitors. The available evidence indicates that the use of other noninsulin medications, including glucagon-like peptide-1 receptor agonists and sulfonylureas, to achieve and maintain glycemic control in the inpatient setting may be limited by adverse effects.

CONCLUSION

Optimal glycemic control in hospitalized patients with diabetes is necessary to avoid adverse effects. Insulin therapy is currently the primary medication recommended for this patient population. DPP-4 inhibitors have been demonstrated to be safe and effective for use in the inpatient setting in patients with well-controlled diabetes. Further research is needed to help define the role of noninsulin medications in the inpatient setting.

Use of incretin-based therapy in hospitalized patients with hyperglycemia

OBJECTIVE

Hyperglycemia is common in hospitalized patients with and without prior history of diabetes and is an independent marker of morbidity and mortality in critically and noncritically ill patients. Tight glycemic control using insulin has been shown to reduce cardiac morbidity and mortality in hospitalized patients, but it also results in hypoglycemic episodes, which have been linked to poor outcomes. Thus, alternative treatment options that can normalize blood glucose levels without undue hypoglycemia are being sought. Incretin-based therapies, such as glucagon-like peptide (GLP)-1 receptor agonists (RAs) and dipeptidyl peptidase (DPP)-4 inhibitors, may have this potential.

METHODS

A PubMed database was searched to find literature describing the use of incretins in hospital settings. Title searches included the terms "diabetes" (care, management, treatment), "hospital," "inpatient," "hypoglycemia," "hyperglycemia," "glycemic," "incretin," "dipeptidyl peptidase-4 inhibitor," "glucagon-like peptide-1," and "glucagon-like peptide-1 receptor agonist."

RESULTS

The preliminary research experience with native GLP-1 therapy has shown promise, achieving improved glycemic control with a low risk of hypoglycemia, counteracting the hyperglycemic effects of stress hormones, and improving cardiac function in patients with heart failure and acute ischemia. Large, randomized controlled clinical trials are necessary to determine whether these favorable results will extend to the use of GLP-1 RAs and DPP-4 inhibitors.

CONCLUSIONS

This review offers hospitalist physicians and healthcare providers involved in inpatient diabetes care a pathophysiologic-based approach for the use of incretin agents in patients with hyperglycemia and diabetes, as well as a summary of benefits and concerns of insulin and incretin-based therapy in the hospital setting.

Exendin-4 Exacerbates Burn-Induced Morbidity in Mice by Activation of the Sympathetic Nervous System

Background

Although glucagon-like peptide 1- (GLP-1-) based therapy of hyperglycemia in burn injury has shown great potential in clinical trials, its safety is seldom evaluated. We hypothesize that exendin-4, a GLP-1 analogue, might affect the immune response via the activation of the sympathetic nervous system in burn injury.

Methods

Male Balb/c mice were subjected to sham or thermal injury of 15% total body surface area. Exendin-4 on T cell function in vitro was examined in cultured splenocytes in the presence of β-adrenoceptor antagonist propranolol (1 nmol/L) or GLP-1R antagonist exendin (9-39) (1 μmol/L), whereas its in vivo effect was determined by i.p. injection of exendin-4 (2.4 nmol/kg) in mice. To further elucidate the sympathetic mechanism, propranolol (30 mg/kg) or vehicle was applied 30 min prior to injury.

Results

Although the exacerbated burn-induced mortality by exendin-4 was worsened by propranolol pretreatment, the inhibition of T cell proliferation by exendin-4 in vitro could be restored by propranolol instead of exendin (9-39). However, a Th2 switch by exendin-4 in vitro could only be reversed by exendin (9-39). Likewise, the inhibition of splenic T cell function and NFAT activity by exendin-4 in vivo was restored by propranolol. By contrast, the increased splenic NF-κB translocation by exendin-4 in vivo was potentiated by propranolol in sham mice but suppressed in burn mice. Accordingly, propranolol abrogated the heightened inflammatory response in the lung and the accelerated organ injuries by exendin-4 in burn mice. On the contrary, a Th2 switch and higher serum levels of inflammatory mediators by exendin-4 were potentiated by propranolol in burn mice. Lastly, exendin-4 raised serum stress hormones which could be remarkably augmented by propranolol.

Conclusions

Exendin-4 suppresses T cell function and promotes organ inflammation through the activation of the sympathetic nervous system, while elicits Th2 switch via GLP-1R in burn injury.

Clinical Effectiveness of Intravenous Exenatide Infusion in Perioperative Glycemic Control after Coronary Artery Bypass Graft Surgery

Background

We aimed to assess the clinical effectiveness of intravenous exenatide compared to insulin in perioperative blood glucose control in coronary artery bypass grafting surgery patients.

Methods

Patients more than 18 yr old admitted for elective coronary artery bypass grafting were included in a phase II/III nonblinded randomized superiority trial. Current insulin use and creatinine clearance of less than 60 ml/min were exclusion criteria. Two groups were compared: the exenatide group, receiving exenatide (1-h bolus of 0.05 µg/min followed by a constant infusion of 0.025 µg/min), and the control group, receiving insulin therapy. The blood glucose target range was 100 to 139 mg/dl. The primary outcome was the proportion of patients who spent at least 50% of the study period within the target range. The consumption of insulin (Cinsulin) and the time to start insulin (Tinsulin) were compared between the two groups.

Results

In total, 53 and 51 patients were included and analyzed in the exenatide and control groups, respectively (age: 70 ± 9 vs. 68 ± 11 yr; diabetes mellitus: 12 [23%] vs. 10 [20%]). The primary outcome was observed in 38 (72%) patients in the exenatide group and in 41 (80%) patients in the control group (odds ratio [95% CI] = 0.85 [0.34 to 2.11]; P = 0.30). Cinsulin was significantly lower (60 [40 to 80] vs. 92 [63 to 121] U, P < 0.001), and Tinsulin was significantly longer (12 [7 to 16] vs. 7 [5 to 10] h, P = 0.02) in the exenatide group.

Conclusions

Exenatide alone at the dose used was not enough to achieve adequate blood glucose control in coronary artery bypass grafting patients, but it reduces overall consumption of insulin and increases the time to initiation of insulin.

Cardiovascular Safety of Antidiabetic Drugs in the Hospital Setting

PURPOSE OF REVIEW

Patients with diabetes and/or stress hyperglycemia requires good glycemic control in the hospital setting, often requiring the use of glucose-lowering therapy. Standard-of-care dictates that non-insulin therapy be discontinued, with insulin therapy initiated using a basal-bolus approach. However, insulin is associated with a high risk for hypoglycemia and medical errors. Alternatives to insulin are needed in the inpatient setting, but the cardiovascular (CV) safety of non-insulin therapy is a concern.

RECENT FINDINGS

Most studies of antidiabetic drugs have been performed in the outpatient setting, and except for insulin therapy, trials in the inpatient setting have been insufficient to establish CV safety. Randomized controlled trials support the safety of insulin with more moderate glycemic control in the hospital, when hypoglycemia is minimized. Two recent multicenter randomized controlled clinical trials support the safety of sitagliptin, a dipeptidylpeptidase-4 inhibitor (DPP4i), in hospitalized patients, although the sample sizes were likely too small to detect CV events. Small trials suggest a possible CV benefit of glucagon-like peptide-1 receptor agonist therapy. A paucity of evidence and presence of side effects and cautions with insulin secretagogues, sodium glucose-co-transporter-2 inhibitors, and metformin preclude their routine use in the hospital setting. Available evidence is inadequate to evaluate the CV safety of most antidiabetic drug classes in the hospital setting. However, preliminary data from randomized clinical trials suggest the potential safety of the DPP4i sitagliptin.

Metabolic and Endocrine Considerations After Burn Injury

Severe burn injury is followed by a profound hypermetabolic response that persists up to 2 years after injury. It is mediated by up to 50-fold elevations in plasma catecholamines, cortisol, and glucagon that lead to whole-body catabolism, elevated resting energy expenditures, and multiorgan dysfunction. Modulation of the response by early excision and grafting of burn wounds, thermoregulation, control of infection, early and continuous enteral nutrition, and pharmacologic treatments aimed at mitigating physiologic derangements have markedly decreased morbidity.

Update on Glucose Management Among Noncritically Ill Patients Hospitalized on Medical and Surgical Wards

Hyperglycemia is a common issue affecting inpatient care. Although this is in part because of the higher rate of hospitalization among patients with preexisting diabetes, multiple factors complicate inpatient glucose management, including acute stress from illness or surgery, erratic dietary intake, and contribution of medications. It has been repeatedly demonstrated that poorly controlled blood glucose levels are associated with negative clinical outcomes, such as increased mortality, higher rate of surgical complications, and longer length of hospital stay. Given these concerns, there has been extensive study of the optimal strategy for management of glucose levels, with the bulk of existing literature focusing on insulin therapy in the intensive care unit setting. This review shifts the focus to the general adult medical and surgical wards, using clinical guidelines and sentinel studies to describe the scientific basis behind the current basal-bolus insulin-based approach to blood sugar management among noncritically ill inpatients. Patient-centered clinical trials looking at alternative dosing regimens and insulin analog and noninsulin agents, such as glucagon-like peptide-1 agonist therapies, introduce safe and effective options in the management of inpatient hyperglycemia. Data from these studies reveal that these approaches are of comparable safety and efficacy to the traditional basal-bolus insulin regimen, and may offer additional benefit in terms of less monitoring requirements and lower rates of hypoglycemia. Although existing data are encouraging, outcome studies will be needed to better establish the clinical impact of these more recently proposed approaches in an effort to broaden and improve current clinical practices in inpatient diabetes care.

Management of hospitalized type 2 diabetes mellitus patients

Both hyperglycemia and hypoglycemia in hospitalized patients are associated with adverse outcomes including increased rates of infection, longer hospital length of stay, and even death. Clinical trials in patients with type 2 diabetes mellitus proved that by improving glycemic control, we can reduce all of them. Insulin is the preferred treatment for glycemic control in most cases, but alternative treatment options that can normalize blood glucose levels without hypoglycemia are being sought. Moreover, hospitalized patients are particularly vulnerable to severe, prolonged hypoglycemia since they may be unable to sense or respond to the early warning signs and symptoms of low blood glucose. Finally, nutritional support, corticosteroid therapy, and surgery increase the risk of hyperglycemia that leads to an increased risk of morbidity and mortality. We review the management of type 2 diabetes mellitus patients who are admitted to the general medical wards of the hospital for a procedure of intercurrent illness.

The metabolic stress response to burn trauma: current understanding and therapies

Major burns provoke a profound stress response, which is unrivalled in terms of its magnitude and duration. Evidence suggests that the pathophysiological stress response to severe burn trauma persists for several years after injury. Thus, there is a pressing need for novel strategies that mitigate this response and restore normal metabolic function in patients with burns. This is the first in a Series of three papers about the care of people with burns. In this paper, we review the current knowledge of the stress response to burn trauma, with a focus on hypermetabolism, muscle wasting, and stress-induced diabetes. We highlight recent developments and important knowledge gaps that need to be pursued to develop novel therapeutic strategies to improve outcomes in burn survivors.

Nutrition and anabolic pharmacotherapies in the care of burn patients

Thermal injury is a devastating injury that results in a number of pathological alterations in almost every system in the body. Hypermetabolism, muscle wasting, depressed immunity, and impaired wound healing are all clinical features of burns. Failure to address each of these specific pathological alterations can lead to increased mortality. Nutrition supplementation has been recommended as a therapeutic tool to help attenuate the hypermetabolism and devastating catabolism evident following burn. Despite the wide consensus on the need of nutrition supplementation in burn patients, controversy exists with regard to the type and amount of nutrition recommended. Nutrition alone is also not enough in these patients to halt and reverse some of the damage done by the catabolic pathways activated following severe burn injury. This has led to the use of anabolic pharmacologic agents in conjunction with nutrition to help improve patient outcome following burn injury. In this review, we examine the relevant literature on nutrition after burn injury and its contribution to the attenuation of the postburn hypermetabolic response, impaired wound healing, and suppressed immunological responses. We also review the commonly used anabolic agents clinically in the care of burn patients. Finally, we provide nutrition and pharmacological recommendations gained from prospective trials, retrospective analyses, and expert opinions based on our practice at the Ross Tilley Burn Center in Toronto, Canada.

The potential role of incretin therapy in the hospital setting

Hyperglycemia has been associated with increased morbidity and mortality in hospitalized patients. Insulin has traditionally been the drug of choice for managing hyperglycemia in this setting, but carries a significant risk of hypoglycemia. Incretin-based therapies, including glucagon-like peptide-1, glucagon-like peptide-1 receptor agonists and dipeptidyl peptidase-4 inhibitors, have potential use in the hospital. These agents have a relatively low risk of hypoglycemia, favorable short-term side effect profile, and can be used alone or in combination with insulin. Several small studies have supported the safety and efficacy of incretin therapies in the inpatient setting with the majority of data coming from the intensive care setting. Large-scale clinical studies are needed to further evaluate the potential role of incretins in the management of inpatient hyperglycemia.

Practical implementation of incretin-based therapy in hospitalized patients with type 2 diabetes

Hyperglycemia in patients with and without a prior history of diabetes is an independent marker of morbidity and mortality in critically and noncritically ill patients. Improvement of glycemic control with insulin therapy has been shown to reduce hospital complications in patients with diabetes, but also results in increased rates of hypoglycemia, which have been linked to poor outcomes. Thus, alternative treatment options that can normalize blood glucose levels without undue hypoglycemia are being sought. Incretin-based therapies, such as glucagon-like peptide-1 receptor agonists and dipeptidyl peptidase-4 inhibitors, stimulate insulin secretion in a glucose-dependent fashion, thus not causing hypoglycemia. Alternative points of view exist regarding insulin versus incretin therapy for the care of these patients. We have brought together the authors on the opposite sides of this discussion with the objective of providing a rational synthesis on how to achieve the best possible control of glycemia in the hospital, using both standard insulin approaches and incretin-based therapies to improve patient outcomes. This review examines the benefits of incretin-based therapy in improving glycemic control in hospitalized patients with stress-induced diabetes and in diabetic patients in critical care and non-critical care settings.

Glucose control in non-critically ill inpatients with diabetes: towards closed-loop

Inpatient glycaemic control remains an important issue due to the increasing number of patients with diabetes admitted to hospital. Morbidity and mortality in hospital are associated with poor glucose control, and cost of hospitalization is higher compared to non-diabetes patients. Guidelines for inpatient glycaemic control in the non-critical care setting have been published. Current recommendations include basal-bolus insulin therapy, regular glucose monitoring, as well as enhancing healthcare provider's role and knowledge. In spite of growing focus, implementation in practice is limited, mainly due to increasing workload burden on staff and fear of hypoglycaemia. Advances in healthcare technology may contribute to an improvement of inpatient diabetes care. Integration of glucose measurements with healthcare records and computerized glycaemic control protocols are currently being used in some institutions. Recent interests in continuous glucose monitoring have led to studies assessing its utilization in inpatients. Automation of glucose monitoring and insulin delivery may provide a safe and efficacious tool for hospital staff to manage inpatient hyperglycaemia, whilst reducing staff workload. This review summarizes the evidence on current approaches to managing inpatient glycaemic control; its utility and limitations. We conclude by discussing the evidence from feasibility studies to date, on the potential use of closed loop in the non-critical care setting and its implication for future studies.

Burns in children: standard and new treatments

Outcomes of patients with burns have improved substantially over the past two decades. Findings from a 2012 study in The Lancet showed that a burn size of more than 60% total body surface area burned (an increase from 40% a decade ago) is associated with risks and mortality. Similar data have been obtained in adults and elderly people who have been severely burned. We discuss recent and future developments in burn care to improve outcomes of children.

The use of non-insulin anti-diabetic agents to improve glycemia without hypoglycemia in the hospital setting: focus on incretins

Patients with hyperglycemia in hospital have increased adverse outcomes compared with patients with normoglycemia, and the pathophysiological causes seem relatively well understood. Thus, a rationale for excellent glycemic control exists. Benefits of control with intensive insulin regimes are highly likely based on multiple published studies. However, hypoglycemia frequency increases and adverse outcomes of hypoglycemia accrue. This has resulted in a 'push' for therapeutic nihilism, accepting higher glycemic levels to avoid hypoglycemia. One would ideally prefer to optimize glycemia, treating hyperglycemia while minimizing or avoiding hypoglycemia. Thus, one would welcome therapies and processes of care to optimize this benefit/ risk ratio. We review the logic and early studies that suggest that incretin therapy use in-hospital can achieve this ideal. We strongly urge randomized prospective controlled studies to test our proposal and we offer a process of care to facilitate this research and their use in our hospitalized patients.

The endocrine response to severe burn trauma

The endocrine system is frequently altered after a major burn trauma. Besides the endocrine response to stress characterized by hypercortisolism, several hypothalamus-hypophysis-target gland axes are rapidly perturbed within a few days. These alterations can persist in the long term and deserve an appropriate treatment. Disturbances in water clearance and glucidic metabolism are also common and need to be diagnosed and corrected to decrease morbidity in such patients. Bone and mineral metabolism is deeply compromised and requires correction of mineral abnormalities in order to improve symptoms and prevent bone loss. No large prospective and/or intervention trials are available to date to elaborate age-related, evidence-based recommendations to monitor and treat burn-related endocrine alterations.

Glucose metabolism in critically ill patients: are incretins an important player?

Critical illness afflicts millions of people worldwide and is associated with a high risk of organ failure and death or an adverse outcome with persistent physical or cognitive deficits. Spontaneous hyperglycemia is common in critically ill patients and is associated with an adverse outcome compared to normoglycemia. Insulin is used for treating hyperglycemia in the critically ill patients but may be complicated by hypoglycemia, which is difficult to detect in these patients and which may lead to serious neurological sequelae and death. The incretin hormone, glucagon-like peptide (GLP) 1, stimulates insulin secretion and inhibits glucagon release both in healthy individuals and in patients with type 2 diabetes (T2DM). Compared to insulin, GLP-1 appears to be associated with a lower risk of severe hypoglycemia, probably because the magnitude of its insulinotropic action is dependent on blood glucose (BG). This is taken advantage of in the treatment of patients with T2DM, for whom GLP-1 analogs have been introduced during the recent years. Infusion of GLP-1 also lowers the BG level in critically ill patients without causing severe hypoglycemia. The T2DM and critical illness share similar characteristics and are, among other things, both characterized by different grades of systemic inflammation and insulin resistance. The GLP-1 might be a potential new treatment target in critically ill patients with stress-induced hyperglycemia.

Clinical review: Glucose control in severely burned patients - current best practice

Tight glucose control changed the way many burn centers practice burn ICU care. However, after the initial impressive data, various clinical trials followed that showed mixed results. The objective of the present review is to discuss recent studies in the area of burn and critical care, and to identify the current best practice for current burn care providers. We reviewed relevant publications from PubMed and selected high-impact publications on tight glycemic control in various patient populations with a focus on burn patients. We conclude that in burns there seems to be a signal that insulin administration to a target range of 130 to 150 mg/dl is beneficial in terms of morbidity and mortality without the risk of hypoglycemia.

Glycemic variability: Clinical implications

Glycemic control and its benefits in preventing microvascular diabetic complications are convincingly proved by various prospective trials. Diabetes control and complications trial (DCCT) had reported variable glycated hemoglobin (HbA1C) as a cause of increased microvascular complications in conventional glycemic control group versus intensive one. However, in spite of several indirect evidences, its link with cardiovascular events or macrovascular complications is still not proved. Glycemic variability (GV) is one more tool to explain relation between hyperglycemia and increased cardiovascular risk in diabetic patients. In fact GV along with fasting blood sugar, postprandial blood sugar, HbA1C, and quality of life has been proposed to form glycemic pentad, which needs to be considered in diabetes management. Postprandial spikes in blood glucose as well as hypoglycemic events, both are blamed for increased cardiovascular events in Type 2 diabetics. GV includes both these events and hence minimizing GV can prevent future cardiovascular events. Modern diabetes management modalities including improved sulfonylureas, glucagon like peptide-1 (GLP-1)-based therapy, newer basal insulins, and modern insulin pumps address the issue of GV effectively. This article highlights mechanism, clinical implications, and measures to control GV in clinical practice.

Is incretin-based therapy ready for the care of hospitalized patients with type 2 diabetes?: The time has come for GLP-1 receptor agonists!

Significant data suggest that overt hyperglycemia, either observed with or without a prior diagnosis of diabetes, contributes to an increase in mortality and morbidity in hospitalized patients. In this regard, goal-directed insulin therapy has remained as the standard of care for achieving and maintaining glycemic control in hospitalized patients with critical and noncritical illness. As such, protocols to assist in the management of hyperglycemia in the inpatient setting have become commonplace in hospital settings. Clearly, insulin is a known entity, has been in clinical use for almost a century, and is effective. However, there are limitations to its use. Based on the observed mechanisms of action and efficacy, there has been a great interest in using incretin-based therapy with glucagon-like peptide-1 (GLP-1) receptor agonists instead of, or complementary to, an insulin-based approach to improve glycemic control in hospitalized, severely ill diabetic patients. To provide an understanding of both sides of the argument, we provide a discussion of this topic as part of this two-part point-counterpoint narrative. In this point narrative as presented below, Drs. Schwartz and DeFronzo provide an opinion that now is the time to consider GLP-1 receptor agonists as a logical consideration for inpatient glycemic control. It is important to note the recommendations they propose under "incretin-based approach" with these agents represent their opinion for use and, as they point out, well-designed prospective studies comparing these agents with insulin will be required to establish their efficacy and safety. In the counterpoint narrative following Drs. Schwartz and DeFronzo's contribution, Drs. Umpierrez and Korytkowski provide a defense of insulin in the inpatient setting as the unquestioned gold standard for glycemic management in hospitalized settings.

Is incretin-based therapy ready for the care of hospitalized patients with type 2 diabetes?: Insulin therapy has proven itself and is considered the mainstay of treatment

Significant data suggest that overt hyperglycemia, either observed with or without a prior diagnosis of diabetes, contributes to an increase in mortality and morbidity in hospitalized patients. In this regard, goal-directed insulin therapy has remained as the standard of care for achieving and maintaining glycemic control in hospitalized patients with critical and noncritical illness. As such, protocols to assist in management of hyperglycemia in the inpatient setting have become commonplace in hospital settings. Clearly, insulin is a known entity, has been in clinical use for almost a century, and is effective. However, there are limitations to its use. Based on the observed mechanisms of action and efficacy, there has been a great interest in using incretin-based therapy with glucagon-like peptide-1 (GLP-1) receptor agonists instead of, or complementary to, an insulin-based approach to improve glycemic control in hospitalized, severely ill diabetic patients. To provide an understanding of both sides of the argument, we provide a discussion of this topic as part of this two-part point-counterpoint narrative. In the point narrative preceding the counterpoint narrative below, Drs. Schwartz and DeFronzo provide an opinion that now is the time to consider GLP-1 receptor agonists as a logical consideration for inpatient glycemic control. In the counterpoint narrative provided below, Drs. Umpierrez and Korytkowski provide a defense of insulin in the inpatient setting as the unquestioned gold standard for glycemic management in hospitalized settings.

Burns: an update on current pharmacotherapy

INTRODUCTION

The worldwide occurrence of burn injuries remains high despite efforts to reduce injury incidence through public awareness campaigns and improvements in living conditions. In 2004, almost 11 million people experienced burns severe enough to warrant medical treatment. Advances over the past several decades in aggressive resuscitation, nutrition, excision and grafting have reduced morbidity and mortality. Incorporation of pharmacotherapeutics into treatment regimens may further reduce complications of severe burn injuries.

AREAS COVERED

Severe burn injuries, as well as other forms of stress and trauma, trigger a hypermetabolic response that, if left untreated, impedes recovery. In the past two decades, use of anabolic agents, β-adrenergic receptor antagonists and anti-hyperglycemic agents has successfully counteracted post-burn morbidities including catabolism, the catecholamine-mediated response and insulin resistance. Here, the authors review the most up-to-date information on currently used pharmacotherapies in the treatment of these sequelae of severe burns and the insights that have expanded the understanding of the pathophysiology of severe burns.

EXPERT OPINION

Existing drugs offer promising advances in the care of burn injuries. Continued gains in the understanding of the molecular mechanisms driving the hypermetabolic response will enable the application of additional existing drugs to be broadened to further attenuate the hypermetabolic response.

Burns: where are we standing with propranolol, oxandrolone, recombinant human growth hormone, and the new incretin analogs?

PURPOSE OF REVIEW

The hypermetabolic response in critically ill patients is characterized by hyperdynamic circulatory, physiologic, catabolic and immune system responses. Failure to satisfy overwhelming energy and protein requirements after, and during critical illness, results in multiorgan dysfunction, increased susceptibility to infection, and death. Attenuation of the hypermetabolic response by various pharmacologic modalities is emerging as an essential component of the management of severe burn patients. This review focuses on the more recent advances in therapeutic strategies to attenuate the hypermetabolic response and its associated insulin resistance postburn.

RECENT FINDINGS

At present, beta-adrenergic blockade with propranolol represents probably the most efficacious anticatabolic therapy in the treatment of burns. Other pharmacological strategies include growth hormone, insulin-like growth factor, oxandrolone and intensive insulin therapy.

SUMMARY

Novel approaches to the management of critical illness by judicious glucose control and the use of pharmacologic modulators to the hypercatabolic response to critical illness have emerged. Investigation of alternative strategies, including the use of metformin, glucagon-like-peptide-1 and the PPAR-γ agonists are under current investigation.

Exogenous glucagon-like peptide-1 attenuates the glycaemic response to postpyloric nutrient infusion in critically ill patients with type-2 diabetes

INTRODUCTION

Glucagon-like peptide-1 (GLP-1) attenuates the glycaemic response to small intestinal nutrient infusion in stress-induced hyperglycaemia and reduces fasting glucose concentrations in critically ill patients with type-2 diabetes. The objective of this study was to evaluate the effects of acute administration of GLP-1 on the glycaemic response to small intestinal nutrient infusion in critically ill patients with pre-existing type-2 diabetes.

METHODS

Eleven critically ill mechanically-ventilated patients with known type-2 diabetes received intravenous infusions of GLP-1 (1.2 pmol/kg/minute) and placebo from t = 0 to 270 minutes on separate days in randomised double-blind fashion. Between t = 30 to 270 minutes a liquid nutrient was infused intraduodenally at a rate of 1 kcal/min via a naso-enteric catheter. Blood glucose, serum insulin and C-peptide, and plasma glucagon were measured. Data are mean ± SEM.

RESULTS

GLP-1 attenuated the overall glycaemic response to nutrient (blood glucose AUC30-270 min: GLP-1 2,244 ± 184 vs. placebo 2,679 ± 233 mmol/l/minute; P = 0.02). Blood glucose was maintained at < 10 mmol/l in 6/11 patients when receiving GLP-1 and 4/11 with placebo. GLP-1 increased serum insulin at 270 minutes (GLP-1: 23.4 ± 6.7 vs. placebo: 16.4 ± 5.5 mU/l; P < 0.05), but had no effect on the change in plasma glucagon.

CONCLUSIONS

Exogenous GLP-1 in a dose of 1.2 pmol/kg/minute attenuates the glycaemic response to small intestinal nutrient in critically ill patients with type-2 diabetes. Given the modest magnitude of the reduction in glycaemia the effects of GLP-1 at higher doses and/or when administered in combination with insulin, warrant evaluation in this group.

TRIAL REGISTRATION

ANZCTR:ACTRN12610000185066.

Bench-to-bedside review: the gut as an endocrine organ in the critically ill

In health, hormones secreted from the gastrointestinal tract have an important role in regulating gastrointestinal motility, glucose metabolism and immune function. Recent studies in the critically ill have established that the secretion of a number of these hormones is abnormal, which probably contributes to disordered gastrointestinal and metabolic function. Furthermore, manipulation of endogenous secretion, physiological replacement and supra-physiological treatment (pharmacological dosing) of these hormones are likely to be novel therapeutic targets in this group. Fasting ghrelin concentrations are reduced in the early phase of critical illness, and exogenous ghrelin is a potential therapy that could be used to accelerate gastric emptying and/or stimulate appetite. Motilin agonists, such as erythromycin, are effective gastrokinetic drugs in the critically ill. Cholecystokinin and peptide YY concentrations are elevated in both the fasting and postprandial states, and are likely to contribute to slow gastric emptying. Accordingly, there is a rationale for the therapeutic use of their antagonists. So-called incretin therapies (glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide) warrant evaluation in the management of hyperglycaemia in the critically ill. Exogenous glucagon-like peptide-2 (or its analogues) may be a potential therapy because of its intestinotropic properties.

The therapeutic potential of a venomous lizard: the use of glucagon-like peptide-1 analogues in the critically ill

Glucagon-like peptide-1 (GLP-1), a principal mediator of the postprandial insulinotropic response in health, has a half-life of minutes. The saliva of the Gila monster contains exendin-4, a structural analogue of human GLP-1, but with a much longer half-life. A synthetic preparation of exendin-4, exenatide, is suitable for human use and effectively lowers glucose in ambulant type 2 diabetic patients. When compared with insulin, exenatide therapy is associated with a reduction in hypoglycaemic episodes and postprandial glycaemic excursions in this group. Accordingly, GLP-1 analogues are appealing therapies for hyperglycaemia in the critically ill patient and warrant further study.