The effect of single doses of pramlintide on gastric emptying of two meals in men with IDDM

A model of subcutaneous pramlintide pharmacokinetics and its effect on gastric emptying: Proof-of-concept based on populational data

Pramlintide, an amylin analog, has been coming up as an agent in type 1 diabetes dual-hormone therapies (insulin/pramlintide). Since pramlintide slows down gastric emptying, it allows for easing glucose control and reducing the burden of meal announcements. Pre-clinical in silico evaluations are a key step in the development of any closed-loop strategy. However, mathematical models are needed, and pramlintide models in the literature are scarce. This work proposes a proof-of-concept pramlintide model, describing its subcutaneous pharmacokinetics (PK) and its effect on gastric emptying (PD). The model is validated with published populational (clinical) data. The model development is divided into three stages: intravenous PK, subcutaneous PK, and PD modeling. In each stage, a set of model structures are proposed, and their performance is assessed using the Akaike Information Criterion (AIC) and the Bayesian Information Criterion (BIC). In order to evaluate the modulation of the rate of gastric emptying, a literature meal model was used. The final pramlintide model comprises four compartments and a function that modulates gastric emptying depending on plasma pramlintide. Results show an appropriate fit for the data. Some aspects are left as open questions due to the lack of specific data (e.g., the influence of meal composition on the pramlintide effect). Moreover, further validation with individual data is necessary to propose a virtual cohort of patients.

Novel insights into the pathogenic impact of diabetes on the gastrointestinal tract

Type 2 and type 1 diabetes are common endocrine disorders with a progressively increasing incidence worldwide. These chronic, systemic diseases have multiorgan implications, and the whole gastrointestinal (GI) tract represents a frequent target in terms of symptom appearance and interdependent pathophysiological mechanisms. Metabolic alterations linked with diabetic complications, neuropathy and disrupted hormone homeostasis can lead to upper and/or lower GI symptoms in up to 75% of diabetic patients, with multifactorial involvement of the oesophagus, stomach, upper and lower intestine, and of the gallbladder. On the other hand, altered gastrointestinal motility and/or secretions are able to affect glucose and lipid homeostasis in the short and long term. Finally, diabetes has been linked with increased cancer risk at different levels of the GI tract. The presence of GI symptoms and a comprehensive assessment of GI function should be carefully considered in the management of diabetic patients to avoid further complications and to ameliorate the quality of life. Additionally, the presence of gastrointestinal dysfunction should be adequately managed to improve metabolic homeostasis, the efficacy of antidiabetic treatments and secondary prevention strategies.

THERAPY OF ENDOCRINE DISEASE: Amylin and calcitonin - physiology and pharmacology

Type 2 diabetes is a common manifestation of metabolic dysfunction due to obesity and constitutes a major burden for modern health care systems, in concert with the alarming rise in obesity worldwide. In recent years, several successful pharmacotherapies improving glucose metabolism have emerged and some of these also promote weight loss, thus, ameliorating insulin resistance. However, the progressive nature of type 2 diabetes is not halted by these new anti-diabetic pharmacotherapies. Therefore, novel therapies promoting weight loss further and delaying diabetes progression are needed. Amylin, a beta cell hormone, has satiating properties and also delays gastric emptying and inhibits postprandial glucagon secretion with the net result of reducing postprandial glucose excursions. Amylin acts through the six amylin receptors, which share the core component with the calcitonin receptor. Calcitonin, derived from thyroid C cells, is best known for its role in humane calcium metabolism, where it inhibits osteoclasts and reduces circulating calcium. However, calcitonin, particularly of salmon origin, has also been shown to affect insulin sensitivity, reduce the gastric emptying rate and promote satiation. Preclinical trials with agents targeting the calcitonin receptor and the amylin receptors, show improvements in several parameters of glucose metabolism including insulin sensitivity and some of these agents are currently undergoing clinical trials. Here, we review the physiological and pharmacological effects of amylin and calcitonin and discuss the future potential of amylin and calcitonin-based treatments for patients with type 2 diabetes and obesity.

The management of type 1 diabetes in adults. A consensus report by the American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD)

The American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD) convened a writing group to develop a consensus statement on the management of type 1 diabetes in adults. The writing group has considered the rapid development of new treatments and technologies and addressed the following topics: diagnosis, aims of management, schedule of care, diabetes self-management education and support, glucose monitoring, insulin therapy, hypoglycaemia, behavioural considerations, psychosocial care, diabetic ketoacidosis, pancreas and islet transplantation, adjunctive therapies, special populations, inpatient management and future perspectives. Although we discuss the schedule for follow-up examinations and testing, we have not included the evaluation and treatment of the chronic microvascular and macrovascular complications of diabetes as these are well-reviewed and discussed elsewhere. The writing group was aware of both national and international guidance on type 1 diabetes and did not seek to replicate this but rather aimed to highlight the major areas that healthcare professionals should consider when managing adults with type 1 diabetes. Though evidence-based where possible, the recommendations in the report represent the consensus opinion of the authors. Graphical abstract.

The Management of Type 1 Diabetes in Adults. A Consensus Report by the American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD)

The American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD) convened a writing group to develop a consensus statement on the management of type 1 diabetes in adults. The writing group has considered the rapid development of new treatments and technologies and addressed the following topics: diagnosis, aims of management, schedule of care, diabetes self-management education and support, glucose monitoring, insulin therapy, hypoglycemia, behavioral considerations, psychosocial care, diabetic ketoacidosis, pancreas and islet transplantation, adjunctive therapies, special populations, inpatient management, and future perspectives. Although we discuss the schedule for follow-up examinations and testing, we have not included the evaluation and treatment of the chronic microvascular and macrovascular complications of diabetes as these are well-reviewed and discussed elsewhere. The writing group was aware of both national and international guidance on type 1 diabetes and did not seek to replicate this but rather aimed to highlight the major areas that health care professionals should consider when managing adults with type 1 diabetes. Though evidence-based where possible, the recommendations in the report represent the consensus opinion of the authors.

Living with the enemy: from protein-misfolding pathologies we know, to those we want to know

Conformational diseases are caused by the aggregation of misfolded proteins. The risk for such pathologies develops years before clinical symptoms appear, and is higher in people with alpha-1 antitrypsin (AAT) polymorphisms. Thousands of people with alpha-1 antitrypsin deficiency (AATD) are underdiagnosed. Enemy-aggregating proteins may reside in these underdiagnosed AATD patients for many years before a pathology for AATD fully develops. In this perspective review, we hypothesize that the AAT protein could exert a new and previously unconsidered biological effect as an endogenous metal ion chelator that plays a significant role in essential metal ion homeostasis. In this respect, AAT polymorphism may cause an imbalance of metal ions, which could be correlated with the aggregation of amylin, tau, amyloid beta, and alpha synuclein proteins in type 2 diabetes mellitus (T2DM), Alzheimer's and Parkinson's diseases, respectively.

Mono and dual agonists of the amylin, calcitonin, and CGRP receptors and their potential in metabolic diseases

BACKGROUND

Therapies for metabolic diseases are numerous, yet improving insulin sensitivity beyond that induced by weight loss remains challenging. Therefore, search continues for novel treatment candidates that can stimulate insulin sensitivity and increase weight loss efficacy in combination with current treatment options. Calcitonin gene-related peptide (CGRP) and amylin belong to the same peptide family and have been explored as treatments for metabolic diseases. However, their full potential remains controversial.

SCOPE OF REVIEW

In this article, we introduce this rather complex peptide family and its corresponding receptors. We discuss the physiology of the peptides with a focus on metabolism and insulin sensitivity. We also thoroughly review the pharmacological potential of amylin, calcitonin, CGRP, and peptide derivatives as treatments for metabolic diseases, emphasizing their ability to increase insulin sensitivity based on preclinical and clinical studies.

MAJOR CONCLUSIONS

Amylin receptor agonists and dual amylin and calcitonin receptor agonists are relevant treatment candidates, especially because they increase insulin sensitivity while also assisting weight loss, and their unique mode of action complements incretin-based therapies. However, CGRP and its derivatives seem to have only modest if any metabolic effects and are no longer of interest as therapies for metabolic diseases.

Adjunct therapies in treatment of type 1 diabetes

In spite of developments with novel insulin preparations, novel modes of insulin delivery with insulin infusion pumps, and the facility of continuous glucose monitoring, only 20% of patients with type 1 diabetes are under adequate control. The need for innovation is clear, and, therefore, the use of adjunct therapies with other pharmacological agents currently in use for type 2 diabetes, has been tried. Currently, pramlintide is the only agent licensed for use in this condition in addition to insulin. Global trials have been conducted with liraglutide, a glucagon-like peptide 1 receptor agonist (GLP-1RA), dapagliflozin, a sodium glucose cotransporter 2 (SGLT2) inhibitor, and sotagliflozin, an inhibitor of both SGLT1 and SGLT2 transporters. While dapagliflozin and sotagliflozin have now been licensed for clinical use in this condition in Europe and Japan, they have hitherto not been licensed in the United States due to a small increase in the risk of diabetic ketoacidosis. However, these agents reduce glycosylated hemoglobin (HbA1c) by 0.4%, reduce glycemic oscillations, and do not increase the risk of hypoglycemia. Liraglutide, on the other hand, induced a smaller reduction in HbA1c and thus was not considered for a license. However, further trials are currently being conducted with a combination of semaglutide, the most potent GLP-1RA, and dapagliflozin to determine whether this approach would yield better outcomes.

Relation between serum amylin level and epilepsy

Background

Epilepsy is a neurological disorder characterized by convulsions. Identification of biological pathways underlying epilepsy and novel genes may shed light on the pathogenesis of epilepsy as well as new targets for treatment.

Objectives

Amylin is cosecreted with insulin from the pancreatic β-cells in a pulsatile manner as a response to nutrient stimuli. In vitro studies have shown the neurotoxicity potential of amylin. We aimed to investigate serum amylin levels between epilepsy patients and a healthy control group.

Subjects and methods

For this study, 45 patients with epilepsy and 60 healthy controls were enrolled. Routine blood analysis and electroencephalography scan were performed for all participants. Five cc venous blood sample was collected from each participant. Sera were isolated and stored at − 80 °C until the time of amylin analysis with the enzyme-linked immunosorbent assay.

Results

Gender distribution of the two groups was as follows: 44.4% males and 55.6% females among epileptic patients and 53.3% males and 46.7% females for control subjects.

Body mass index was 23.09 ± 3.99 kg/m2 for epileptic patients and 26.29 ± 4.83 kg/m2 for controls, with a statistically significantly higher body mass index in control subjects (p ˂ 0.001). With regard to serum amylin levels, a statistically significant difference was observed between the two groups (p ˂ 0.001). The median serum amylin concentration was 226.62 ng/ml (69.49–6961.19 (min–max)) for epileptic patients and 103.66 ng/ml (37.42–607.11 (min–max)) for controls (p ˂ 0.001).

Conclusion

In the present study, a significant difference was observed between patient and control groups in serum amylin concentrations, which were considerably higher in epileptic patients.

Diabetic Gastroparesis and Glycaemic Control

PURPOSE OF REVIEW

Gastroparesis is an important complication of diabetes that may have a major impact on the quality of life as a result of upper gastrointestinal symptoms and impaired glycaemic control. Current management strategies include optimising blood glucose control, dietary modifications and supportive nutrition. Pharmacologic approaches with drugs that have prokinetic and/or antiemetic effects are also used widely; however, current available treatments have major limitations. There is increasing recognition that the rate of gastric emptying (GE) is a key determinant of the glycaemic response to a meal.

RECENT FINDINGS

There is ongoing uncertainty regarding the impact of longstanding hyperglycaemia on GE, which requires clarification. New diagnostic techniques have been developed to better characterise the mechanisms underlying gastroparesis in individual patients, and these have the potential to lead to more personalised therapy. Management of gastroparesis is complex and suboptimal; novel approaches are desirable. This review summarises recent advances in the understanding of diabetic gastroparesis, with an emphasis on the current therapies that influence GE, and the bidirectional relationship between glycaemic control and GE.

Anti-Obesity Therapy: from Rainbow Pills to Polyagonists

With their ever-growing prevalence, obesity and diabetes represent major health threats of our society. Based on estimations by the World Health Organization, approximately 300 million people will be obese in 2035. In 2015 alone there were more than 1.6 million fatalities attributable to hyperglycemia and diabetes. In addition, treatment of these diseases places an enormous burden on our health care system. As a result, the development of pharmacotherapies to tackle this life-threatening pandemic is of utmost importance. Since the beginning of the 19th century, a variety of drugs have been evaluated for their ability to decrease body weight and/or to improve deranged glycemic control. The list of evaluated drugs includes, among many others, sheep-derived thyroid extracts, mitochondrial uncouplers, amphetamines, serotonergics, lipase inhibitors, and a variety of hormones produced and secreted by the gastrointestinal tract or adipose tissue. Unfortunately, when used as a single hormone therapy, most of these drugs are underwhelming in their efficacy or safety, and placebo-subtracted weight loss attributed to such therapy is typically not more than 10%. In 2009, the generation of a single molecule with agonism at the receptors for glucagon and the glucagon-like peptide 1 broke new ground in obesity pharmacology. This molecule combined the beneficial anorectic and glycemic effects of glucagon-like peptide 1 with the thermogenic effect of glucagon into a single molecule with enhanced potency and sustained action. Several other unimolecular dual agonists have subsequently been developed, and, based on their preclinical success, these molecules illuminate the path to a new and more fruitful era in obesity pharmacology. In this review, we focus on the historical pharmacological approaches to treat obesity and glucose intolerance and describe how the knowledge obtained by these studies led to the discovery of unimolecular polypharmacology.

Non-insulin pharmacological therapies for treating type 1 diabetes

INTRODUCTION

Despite intensified insulin treatment, many persons with type 1 diabetes (T1D) do not achieve glycemic and metabolic targets. Consequently, non-insulin chemical therapies that improve glycemic control and metabolic parameters without increasing the risk of adverse events (including hypoglycemia) are of interest as adjunct therapies to insulin.

AREAS COVERED

In this review, the authors discuss the efficacy and safety of non-insulin therapies, including pramlintide, glucagon-like peptide-1 (GLP-1) receptor agonists, dipeptidyl peptidase-4 inhibitors (DPP-4), sodium-glucose cotransporter (SGLT1 and SGLT2) inhibitors, metformin, sulfonylureas, and thiazolidinediones as add-on therapies to insulin in T1D.

EXPERT OPINION

The current evidence shows that the efficacy of non-insulin therapies as add-on therapies to insulin is minimal or modest with an average HbA1c reduction of 0.2-0.5% (2-6 mmol/mol). Indeed, the current focus is on the development of SGLT inhibitors as adjuncts to insulin in type 1 diabetes. Studies of subgroups with obesity, residual beta-cell function (including newly diagnosed patients) and patients prone to hypoglycemia could be areas of future research.

Gastrointestinal Symptoms in Diabetes: Prevalence, Assessment, Pathogenesis, and Management

If you haven't measured something, you really don't know much about it.-Karl Pearson (attributed)Gastrointestinal (GI) symptoms represent an important and often unappreciated cause of morbidity in diabetes, although the significance of this burden across the spectrum of patients and the underlying pathophysiology, including the relationship of symptoms with glycemic control, remain poorly defined. The relevance of GI symptoms and the necessity for their accurate assessment have increased with the greater focus on the gut as a therapeutic target for glucose lowering. This review addresses the prevalence, assessment, pathogenesis, and management of GI symptoms in diabetes, beginning with broad principles and then focusing on specific segments of the GI tract. We initially performed a literature search of PubMed by using synonyms and combinations of the following search terms: "gastrointestinal symptoms", "diabetes", "prevalence", "pathogenesis", "diagnosis", and "management". We restricted the search results to English only. Review papers and meta-analyses are presented as the highest level of evidence where possible followed by randomized controlled trials, uncontrolled trials, retrospective and observational data, and expert opinion.

IAPP and type 1 diabetes: implications for immunity, metabolism and islet transplants

Islet amyloid polypeptide (IAPP), the main component of islet amyloid in type 2 diabetes and islet transplants, is now recognized as a contributor to beta cell dysfunction. Increasingly, evidence warrants its investigation in type 1 diabetes owing to both its immunomodulatory and metabolic actions. Autoreactive T cells to IAPP-derived epitopes have been described in humans, suggesting that IAPP is an islet autoantigen in type 1 diabetes. In addition, although aggregates of IAPP have not been implicated in type 1 diabetes, they are potent pro-inflammatory stimuli to innate immune cells, and thus, could influence autoimmunity. IAPP aggregates also occur rapidly in transplanted islets and likely contribute to islet transplant failure in type 1 diabetes through sterile inflammation. In addition, since type 1 diabetes is a disease of both insulin and IAPP deficiency, clinical trials have examined the potential benefits of IAPP replacement in type 1 diabetes with the injectable IAPP analogue, pramlintide. Pramlintide limits postprandial hyperglycemia by delaying gastric emptying and suppressing hyperglucagonemia, underlining the possible role of IAPP in postprandial glucose metabolism. Here, we review IAPP in the context of type 1 diabetes: from its potential involvement in type 1 diabetes pathogenesis, through its role in glucose metabolism and use of IAPP analogues as therapeutics, to its potential role in clinical islet transplant failure and considerations in this regard for future beta cell replacement strategies.

Development of proteolytically stable N-methylated peptide inhibitors of aggregation of the amylin peptide implicated in type 2 diabetes

Islet amyloid polypeptide, also known as amylin, is the main component of the amyloid deposits present in approximately 90% of people with type 2 diabetes mellitus (T2DM). In this disease, amylin aggregates into multimeric β-pleated sheet structures which cause damage to pancreatic islet β-cells. Inhibitors of early-stage amylin aggregation could therefore provide a disease-modifying treatment for T2DM. In this study, overlapping peptides were designed to target the 'binding' region (RLANFLVHSS, residues 11-20) of human amylin, and their effects on amyloid fibril formation were determined by thioflavin-T assay. The first generation peptides showed less than 50% inhibition of aggregation, but a second generation peptide (H₂N-RGANFLVHGR-CONH₂) showed strong inhibitory effects on amylin aggregation, and this was confirmed by negative stain electron microscopy. Cytotoxicity studies revealed that this peptide protected human pancreatic 1.4E7 (ECACC 10070102) insulin-secreting cells from the toxic effects of human amylin. Unlike the retro-inverso version of this peptide, which stimulated aggregation, two N-methylated peptides (H₂N-RGAmNFmLVmHGR-CONH₂ and H₂N-RGANmFLmVHmR-CONH₂) gave very clear dose-dependent inhibition of fibril formation. These two peptides were also stable against a range of different proteolytic enzymes, and in human plasma. These N-methylated peptides could provide a novel treatment for slowing progression of T2DM.

The New Biology and Pharmacology of Glucagon

In the last two decades we have witnessed sizable progress in defining the role of gastrointestinal signals in the control of glucose and energy homeostasis. Specifically, the molecular basis of the huge metabolic benefits in bariatric surgery is emerging while novel incretin-based medicines based on endogenous hormones such as glucagon-like peptide 1 and pancreas-derived amylin are improving diabetes management. These and related developments have fostered the discovery of novel insights into endocrine control of systemic metabolism, and in particular a deeper understanding of the importance of communication across vital organs, and specifically the gut-brain-pancreas-liver network. Paradoxically, the pancreatic peptide glucagon has reemerged in this period among a plethora of newly identified metabolic macromolecules, and new data complement and challenge its historical position as a gut hormone involved in metabolic control. The synthesis of glucagon analogs that are biophysically stable and soluble in aqueous solutions has promoted biological study that has enriched our understanding of glucagon biology and ironically recruited glucagon agonism as a central element to lower body weight in the treatment of metabolic disease. This review summarizes the extensive historical record and the more recent provocative direction that integrates the prominent role of glucagon in glucose elevation with its under-acknowledged effects on lipids, body weight, and vascular health that have implications for the pathophysiology of metabolic diseases, and the emergence of precision medicines to treat metabolic diseases.

Non-insulin drugs to treat hyperglycaemia in type 1 diabetes mellitus

Insulin treatment of individuals with type 1 diabetes has shortcomings and many patients do not achieve glycaemic and metabolic targets. Consequently, the focus is on novel non-insulin therapeutic approaches that reduce hyperglycaemia and improve metabolic variables without increasing the risk of hypoglycaemia or other adverse events. Several therapies given in conjunction with insulin have been investigated in clinical trials, including pramlintide, glucagon-like peptide-1 receptor agonists, dipeptidyl peptidase-4 inhibitors, sodium-glucose co-transporter inhibitors, metformin, sulfonylureas, and thiazolidinediones. These drugs have pleiotropic effects on glucose metabolism and different actions complementary to those of insulin-this Review reports the effects of these drugs on glycaemic control, glucose variability, hypoglycaemia, insulin requirements, and bodyweight. Existing studies are of short duration with few participants; evidence for the efficacy of concomitant treatments is scarce and largely clinically insignificant. A subgroup of patients with type 1 diabetes for whom non-insulin antidiabetic drugs could significantly benefit glycaemic control cannot yet be defined, but we suggest that obese patients prone to hypoglycaemia and patients with residual β-cell function are populations of interest for future trials.

Amylin analogue as an antidiabetic agent

The amylin analogue pramlintide (SYMLIN®) is the first in a new class of injectable amylinomimetic agents to be approved for the treatment of diabetes. This adjunct to insulin treatment of type 1 and type 2 diabetes has recently been approved for use in the USA. Pramlintide, unlike native amylin is soluble. It acts mainly via central effects (area postrema) resulting in deceased glucagon secretion, slowing gastric emptying and a satiety effect. It is injected subcutaneously separately from insulin, and usually before each of the main meals. It has been shown to improve glycaemic control without causing weight gain but the dose must be titrated slowly in association with appropriate insulin adjustments to guard against insulin-induced hypoglycaemia and nausea. Thus, pramlintide is an injected amylin replacement therapy that can be used with an insulin regimen to improve glycaemic control without weight gain.

Amylin-mediated control of glycemia, energy balance, and cognition

Amylin, a peptide hormone produced in the pancreas and in the brain, has well-established physiological roles in glycemic regulation and energy balance control. It improves postprandial blood glucose levels by suppressing gastric emptying and glucagon secretion; these beneficial effects have led to the FDA-approved use of the amylin analog pramlintide in the treatment of diabetes mellitus. Amylin also acts centrally as a satiation signal, reducing food intake and body weight. The ability of amylin to promote negative energy balance, along with its unique capacity to cooperatively facilitate or enhance the intake- and body weight-suppressive effects of other neuroendocrine signals like leptin, have made amylin a leading target for the development of novel pharmacotherapies for the treatment of obesity. In addition to these more widely studied effects, a growing body of literature suggests that amylin may play a role in processes related to cognition, including the neurodegeneration and cognitive deficits associated with Alzheimer's disease (AD). Although the function of amylin in AD is still unclear, intriguing recent reports indicate that amylin may improve cognitive ability and reduce hallmarks of neurodegeneration in the brain. The frequent comorbidity of diabetes mellitus and obesity, as well as the increased risk for and occurrence of AD associated with these metabolic diseases, suggests that amylin-based pharmaceutical strategies may provide multiple therapeutic benefits. This review will discuss the known effects of amylin on glycemic regulation, energy balance control, and cognitive/motivational processes. Particular focus will be devoted to the current and/or potential future clinical use of amylin pharmacotherapies for the treatment of diseases in each of these realms.

Amylin: Pharmacology, Physiology, and Clinical Potential

Amylin is a pancreatic β-cell hormone that produces effects in several different organ systems. Here, we review the literature in rodents and in humans on amylin research since its discovery as a hormone about 25 years ago. Amylin is a 37-amino-acid peptide that activates its specific receptors, which are multisubunit G protein-coupled receptors resulting from the coexpression of a core receptor protein with receptor activity-modifying proteins, resulting in multiple receptor subtypes. Amylin's major role is as a glucoregulatory hormone, and it is an important regulator of energy metabolism in health and disease. Other amylin actions have also been reported, such as on the cardiovascular system or on bone. Amylin acts principally in the circumventricular organs of the central nervous system and functionally interacts with other metabolically active hormones such as cholecystokinin, leptin, and estradiol. The amylin-based peptide, pramlintide, is used clinically to treat type 1 and type 2 diabetes. Clinical studies in obesity have shown that amylin agonists could also be useful for weight loss, especially in combination with other agents.

Measurement of gastric emptying in diabetes

There has been a substantial evolution of concepts related to disordered gastric emptying in diabetes. While the traditional focus has hitherto related to the pathophysiology and management of upper gastrointestinal symptoms associated with gastroparesis, it is now apparent that the rate of gastric emptying is central to the regulation of postprandial glycemia. This recognition has stimulated the development of dietary and pharmacologic approaches to optimize glycemic control, at least in part, by slowing gastric emptying. With the increased clinical interest in this area, it has proved necessary to expand the traditional indications for gastric emptying studies, and consider the relative strengths and limitations of available techniques. Scintigraphy remains the 'gold standard' for the measurement of gastric emptying, however, there is a lack of standardization of the technique, and the optimal test meal for the evaluation of gastrointestinal symptoms may be discordant from that which is optimal to assess impaired glycemic control. The stable isotope breath test provides an alternative to scintigraphy and can be performed in an office-based setting. The effect of glucagon-like peptide-1 (GLP-1) and its agonists to reduce postprandial glycemia is dependent on the baseline rate of gastric emptying, as well as the magnitude of slowing. Because the effect of exogenous GLP-1 to slow gastric emptying is subject to tachyphylaxis with sustained receptor exposure, 'short acting' or 'prandial' GLP-1 agonists primarily target postprandial glycemia through slowing of gastric emptying, while 'long acting' or 'non-prandial' agents lower fasting glucose primarily through insulinotropic and glucagonostatic mechanisms. Accordingly, the indications for the therapeutic use of these different agents are likely to vary according to baseline gastric emptying rate and glycemic profiles.

Effects of delayed gastric emptying on postprandial glucose kinetics, insulin sensitivity, and β-cell function

Controlling meal-related glucose excursions continues to be a therapeutic challenge in diabetes mellitus. Mechanistic reasons for this need to be understood better to develop appropriate therapies. To investigate delayed gastric emptying effects on postprandial glucose turnover, insulin sensitivity, and β-cell responsivity and function, as a feasibility study prior to studying patients with type 1 diabetes, we used the triple tracer technique C-peptide and oral minimal model approach in healthy subjects. A single dose of 30 μg of pramlintide administered at the start of a mixed meal was used to delay gastric emptying rates. With delayed gastric emptying rates, peak rate of meal glucose appearance was delayed, and rate of endogenous glucose production (EGP) was lower. C-peptide and oral minimal models enabled the assessments of β-cell function, insulin sensitivity, and β-cell responsivity simultaneously. Delayed gastric emptying induced by pramlintide improved total insulin sensitivity and decreased total β-cell responsivity. However, β-cell function as measured by total disposition index did not change. The improved whole body insulin sensitivity coupled with lower rate of appearance of EGP with delayed gastric emptying provides experimental proof of the importance of evaluating pramlintide in artificial endocrine pancreas approaches to reduce postprandial blood glucose variability in patients with type 1 diabetes.

Treating the elderly diabetic patient: special considerations

The prevalence of diabetes is rising in the >65 year-old group. The challenge of defining the goals of therapy arises from the heterogeneity of the aging process and the sparse clinical data in this patient population. In light of these challenges, the clinician should be aware of the pitfalls of caring for the older diabetic patient and prioritize an individualized treatment plan to ensure an optimal glycemic control, without placing the patient at unnecessary risk. We present a review of the current guidelines and literature that deal specifically with the treatment of the older diabetic patient in order to establish the principles of treatment in this age group and help the clinician make decisions regarding the care of these patients.

A model of glucose-insulin-pramlintide pharmacokinetics and pharmacodynamics in type I diabetes

Type 1 diabetes mellitus (T1DM) complications are significantly reduced when normoglycemic levels are maintained via intensive therapy. The artificial pancreas is designed for intensive glycemic control; however, large postprandial excursions after a meal result in poor glucose regulation. Pramlintide, a synthetic analog of the hormone amylin, reduces the severity of postprandial excursions by reducing appetite, suppressing glucagon release, and slowing the rate of gastric emptying. The goal of this study is to create a glucose-insulin-pramlintide physiological model that can be employed into a controller to improve current control approaches used in the artificial pancreas. A model of subcutaneous (SC) pramlintide pharmacokinetics (PK) was developed by revising an intravenous (IV) pramlintide PK model and adapting SC insulin PK from a glucose-insulin model. Gray-box modeling and least squares optimization were used to obtain parameter estimates. Pharmacodynamics (PD) were obtained by choosing parameters most applicable to pramlintide mechanisms and then testing using a proportional PD effect using least squares optimization. The model was fit and validated using 27 data sets, which included placebo, PK, and PD data. SC pramlintide PK root mean square error values range from 1.98 to 10.66 pmol/L. Pramlintide PD RMSE values range from 10.48 to 42.76 mg/dL. A new in silico model of the glucose-insulin-pramlintide regulatory system is presented. This model can be used as a platform to optimize dosing of both pramlintide and insulin as a combined therapy for glycemic regulation, and in the development of an artificial pancreas as the kernel for a model-based controller.

In silico design of optimal ratio for co-administration of pramlintide and insulin in type 1 diabetes

BACKGROUND

The ability to simulate in silico experiments is crucial for fast and cost-effective preliminary studies prior to clinical trials. We present an in silico approach to the design of optimal pramlintide-to-insulin (P/I) ratios, using our computer simulator of the human metabolic system, with a population of virtual adult type 1 diabetes mellitus patients and with individual parameters modified to account for the dynamic effects of pramlintide.

MATERIALS AND METHODS

A model of pramlintide action on gastric emptying was built using data of 15 type 1 diabetes mellitus subjects studied twice with a standardized dual-tracer meal on placebo and pramlintide, which was incorporated in our type 1 diabetes simulator. Extensive in silico experiments on 100 virtual subjects were performed to optimize the co-administration of pramlintide and insulin prior to its submission to clinical trials; several P/I ratios were tested in terms of efficacy, in attenuating postprandial hyperglycemia, and in hypoglycemia safety.

RESULTS

In silico experiments estimated the optimal P/I ratio to be 9 μg of pramlintide per unit (U) of insulin. Additional simulations narrowing the investigated range indicated that P/I ratios of 8 and 10 μg/U would achieve similar performance. Moreover, simulation results suggested that in clinical trials, insulin boluses should be reduced by approximately 21% at a P/I ratio of 9 μg/U to account for the effects of pramlintide and avoid postprandial hypoglycemia.

CONCLUSIONS

We can assert that a valid simulation model of pramlintide action was developed, leading to in silico estimation of optimal pramlintide:insulin co-administration ratio. Clinical trials will confirm (or adjust) this initial estimation.

Amylin uncovered: a review on the polypeptide responsible for type II diabetes

Amylin is primarily responsible for classifying type II diabetes as an amyloid (protein misfolding) disease as it has great potential to aggregate into toxic nanoparticles, thereby resulting in loss of pancreatic β-cells. Although type II diabetes is on the increase each year, possibly due to bad eating habits of modern society, research on the culprit for this disease is still in its early days. In addition, unlike the culprit for Alzheimer's disease, amyloid β-peptide, amylin has failed to receive attention worthy of being featured in an abundance of review articles. Thus, the aim of this paper is to shine the spotlight on amylin in an attempt to put it onto the top of researchers' to-do list since the secondary complications of type II diabetes have far-reaching and severe consequences on public health both in developing and fully developed countries alike. This paper will cover characteristics of the amylin aggregates, mechanisms of toxicity, and a particular focus on inhibitors of toxicity and techniques used to assess these inhibitors.

Study reanalysis using a mechanism-based pharmacokinetic/pharmacodynamic model of pramlintide in subjects with type 1 diabetes

This report describes a pharmacokinetic/pharmacodynamic model for pramlintide, an amylinomimetic, in type 1 diabetes mellitus (T1DM). Plasma glucose and drug concentrations were obtained following bolus and 2-h intravenous infusions of pramlintide at three dose levels or placebo in 25 T1DM subjects during the postprandial period in a crossover study. The original clinical data were reanalyzed by mechanism-based population modeling. Pramlintide pharmacokinetics followed a two-compartment model with zero-order infusion and first-order elimination. Pramlintide lowered overall postprandial plasma glucose AUC (AUC(net)) and delayed the time to peak plasma glucose after a meal (T (max)). The delay in glucose T (max) and reduction of AUC(net) indicate that overall plasma glucose concentrations might be affected by differing mechanisms of action of pramlintide. The observed increase in glucose T (max) following pramlintide treatment was independent of dose within the studied dose range and was adequately described by a dose-independent, maximum pramlintide effect on gastric emptying of glucose in the model. The inhibition of endogenous glucose production by pramlintide was described using a sigmoidal function with capacity and sensitivity parameter estimates of 0.995 for I (max) and 23.8 pmol/L for IC(50). The parameter estimates are in good agreement with literature values and the IC(50) is well within the range of postprandial plasma amylin concentrations in healthy humans, indicating physiological relevance of the pramlintide effect on glucagon secretion in the postprandial state. This model may prove to be useful in future clinical studies of other amylinomimetics or antidiabetic drugs with similar mechanisms of action.

Control of energy homeostasis by amylin

Amylin is an important control of nutrient fluxes because it reduces energy intake, modulates nutrient utilization by inhibiting postprandial glucagon secretion, and increases energy disposal by preventing compensatory decreases of energy expenditure in weight-reduced individuals. The best investigated function of amylin which is cosecreted with insulin is to reduce eating by promoting meal-ending satiation. This effect is thought to be mediated by a stimulation of specific amylin receptors in the area postrema. Secondary brain sites to mediate amylin action include the nucleus of the solitary tract and the lateral parabrachial nucleus, which convey the neural signal to the lateral hypothalamic area and other hypothalamic nuclei. Amylin may also signal adiposity because plasma levels of amylin are increased in adiposity and because higher amylin concentrations in the brain result in reduced body weight gain and adiposity, while amylin receptor antagonists increase body adiposity. The central mechanisms involved in amylin's effect on energy expenditure are much less known. A series of recent experiments in animals and humans indicate that amylin is a promising option for anti-obesity therapy especially in combination with other hormones. The most extensive dataset is available for the combination therapy of amylin and leptin. Ongoing research focuses on the mechanisms of these interactions.

Glucoregulatory effects and prolonged duration of action of davalintide: a novel amylinomimetic peptide

AIMS

Davalintide is a second-generation amylinomimetic peptide possessing enhanced pharmacological properties over rat amylin to reduce food intake in preclinical models. The current experiments in rats describe additional glucoregulatory actions of davalintide consistent with amylin agonism, and explore the duration of action of these effects.

METHODS

Subcutaneous (SC) injection of davalintide slowed gastric emptying with equal potency to amylin (ED₅₀'s = 2.3 and 4.1 µg/kg). This effect was maintained for 8 h with davalintide, but not amylin. Intraperitoneal injection of davalintide also reduced food intake with a potency similar to amylin (ED₅₀'s = 5.0 and 11.3 µg/kg). Consistent with amylin agonism, davalintide (10 µg/kg, SC) suppressed the plasma glucagon response over 90 min following an intravenous arginine bolus in anaesthetized rats. The elimination t(½) of davalintide (200 µg/kg, SC) was 26 min, similar to the t(½) of amylin, suggesting that pharmacokinetic-independent mechanisms contribute to davalintide's enhanced duration of action. Binding kinetic studies using ¹²⁵I davalintide revealed no appreciable dissociation from the amylin nucleus accumbens receptor after 7 h while ¹²⁵I rat amylin did dissociate from this receptor (K(off) = 0.013/min). Sustained SC infusion of davalintide (275 µg/kg/day) or amylin (300) decreased plasma glucose after an oral glucose challenge at 2 weeks (by 27 and 31%) and suppressed gastric emptying at 3 weeks (by 29 and 47%), demonstrating durable glucoregulatory actions of both peptides.

CONCLUSIONS

These data show glucoregulatory properties of davalintide consistent with amylin agonism and suggest that slowed receptor dissociation plays a role in davalintide's prolonged pharmacodynamic actions.

Adjunct therapy for type 1 diabetes mellitus

Insulin replacement therapy in type 1 diabetes mellitus (T1DM) is nonphysiologic. Hyperinsulinemia is generated in the periphery to achieve normal insulin concentrations in the liver. This mismatch results in increased hypoglycemia, increased food intake with weight gain, and insufficient regulation of postprandial glucose excursions. Islet amyloid polypeptide is a hormone synthesized in pancreatic beta cells and cosecreted with insulin. Circulating islet amyloid polypeptide binds to receptors located in the hindbrain and increases satiety, delays gastric emptying and suppresses glucagon secretion. Thus, islet amyloid polypeptide complements the effects of insulin. T1DM is a state of both islet amyloid polypeptide and insulin deficiency. Pramlintide, a synthetic analog of islet amyloid polypeptide, can replace this hormone in patients with T1DM. When administered as adjunctive therapy to such patients treated with insulin, pramlintide decreases food intake and causes weight loss. Pramlintide therapy is also associated with suppression of glucagon secretion and delayed gastric emptying, both of which decrease postprandial plasma glucose excursions. Pramlintide therapy improves glycemic control and lessens weight gain. Agents that decrease intestinal carbohydrate digestion (alpha-glucosidase inhibitors) or decrease insulin resistance (metformin) might be alternative adjunctive therapies in T1DM, though its benefits are marginally supported by clinical data.

Characterization of cardiovascular outcomes in a type 2 diabetes glucose supply and insulin demand model

BACKGROUND

The nonsignificant reduction in macrovascular outcomes observed in Action to Control Cardiovascular Risk in Diabetes; Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation; and the Veterans Affairs Diabetes Trial have collectively created uncertainty with respect toward the proper extent of blood glucose reduction and also the optimal therapeutic choice to attain the reduction. In the article entitled "Glucose Supply and Insulin Demand Dynamics of Antidiabetic Agents" in this issue of Journal of Diabetes Science and Technology, we presented data for a pharmacokinetic/pharmacodynamic model that characterizes the effect of conventional antidiabetic therapies on the glucose supply and insulin demand dynamic. Here, it is our objective to test the hypothesis that, in conjunction with hemoglobin A1c (HbA1c), patients managed on the glucose supply side of the model would have fewer cardiovascular events versus those managed on the insulin demand side.

METHODS

To test this hypothesis, the electronic medical records of a group model health maintenance organization were queried to compile a population of patients meeting the following inclusion criteria: (1) type 2 diabetes mellitus (T2DM), (2) known date of T2DM diagnosis; (3) ICD-9 or CPT code identification and chart review confirmation of a first major cardiovascular event (myocardial infarction, coronary artery bypass graft, or angioplasty),(4) five years of continuous eligibility, and (5) on antidiabetic therapy at the beginning of the 5-year observation period. These patients were subsequently matched (1:1) to T2DM patients meeting the same criteria who had not experienced an event and were analyzed for differences in glucose control (HbA1C), the glucose supply:insulin demand dynamic (SD ratio), and categorical combinations of both parameters.

RESULTS

Fifty cardiovascular event patients met inclusion criteria and were matched to controls. No difference was observed for the average HbA1c or SD ratio between patients experiencing an event and controls (7.5 +/- 1.0% versus 7.3 +/- 0.9%, p = .275, and 1.2 +/- 0.3 versus 1.3 +/- 0.3, p = .205, respectively). Likewise, for categorical representations, there were no differences in event rate at the pre-identified breakpoints (HbA1c >or=7% versus <7%; 72% versus 64%, p = .391, and SD ratio >or=1 versus <1; 68% versus 76%, p = .373, >or=1.25 versus <1.25; 42% versus 56%, p = .161, >or=1.5 versus <1.5; 22% versus 30%, p = .362, respectively). Analyzing the combined effect of glucose control and the SD dynamic, patients managed at higher glucose values and on the insulin demand side of the model (HbA1c >or=7% and SD ratio <1.25) tended to have greater cardiovascular risk than those managed at an HbA1c <7%, or HbA1c >or=7% with an SD ratio >or=1.25 (61% versus 39%; p = .096).

CONCLUSION

Independently, more aggressive HbA1c reduction and higher SD ratio values were not independently associated with a reduction in cardiovascular outcomes. Combining the parameters, it would appear that patients managed at higher glucose values and on the insulin demand side of the model may have increased cardiovascular risk. Based on these findings, it is pertinent to conduct subsequent works to refine SD ratio estimates and apply the model to larger, long-term T2DM cardiovascular outcome trials. J Diabetes Sci Technol 2010;4(2):382-390.

Comparison of the post-meal glucose response to different insulin bolus waveforms in insulin pump- and pre-meal pramlintide-treated type 1 diabetes patients

BACKGROUND

Both pramlintide and insulin pump waveforms separately provide improved post-meal glucose control. However, when used together there may be a mismatch in actions leading to hypoglycemia. We studied the three currently available waveforms and a "modified combination wave" (MC) in pramlintide-treated patients. The MC was a "square" (SQ) wave combined with a "standard" (ST) bolus that was delayed 1 h into the mealtime.

METHODS

Using the CGMS Gold (Medtronics, Northridge, CA) we measured the glucose response 0-4 h after the beginning of a meal and 15 min after the initiation of the insulin bolus wave and pramlintide (60 microg), bolus. Pump-treated type 1 diabetes subjects were randomized to one bolus waveform for one full day of three meals and then crossed over to the other bolus waveforms. In the first study nine subjects were randomized to the ST, SQ, or "combination" (C) wave consisting of a ST wave at the beginning of a SQ wave. In the second study nine subjects were randomized to SQ or MC.

RESULTS

With ST and C waves glucose fell approximately 40 mg/dL 0-2 h post-meal and then returned to baseline by the fourth hour. Initially isoglycemic, the SQ wave increased approximately 20 mg/dL in the late meal period. The MC demonstrated minimal (approximately 10 mg/dL) change during the entire post-meal period.

CONCLUSIONS

For currently available insulin pump bolus waves, SQ and MC may be least likely to cause hypoglycemia in pramlintide-treated patients.

Diabetes medications and body weight

Tight diabetes control sometimes comes with a price: weight gain and hypoglycemia. Two of the three major recent trials that looked at the relationship between intensive diabetes control and cardiovascular events reported significant weight gain among the intensively treated groups. There is a growing concern that the weight gain induced by most diabetes medications diminishes their clinical benefits. On the other hand, there is a claim that treating diabetes with medications that are weight neutral or induces weight loss or less weight gain while minimizing those that increase body weight may emerge as the future direction for treating overweight and obese patients with diabetes. This review clarifies the weight effect of each of the currently available diabetes medications, and explains the mechanism of action behind this effect. Despite the great variability among reviewed clinical trials, the currently available evidence is quite sufficient to demonstrate the change in body weight in association with most of the currently available medications. This review also provides some guidelines on using diabetes medications during weight management programs.

A pilot trial of pramlintide home usage in adolescents with type 1 diabetes

OBJECTIVE

The objective of this study was to evaluate the safety and efficacy of home pramlintide use in adolescents with type 1 diabetes.

PATIENTS AND METHODS

This was a randomized, 28-day pilot trial of pramlintide (maximum dose: 30 microg per meal) in 10 adolescents aged 13 to 17 years. End points included changes in hemoglobin A1c (HbA1c) values, body weight, and postprandial peak blood glucose levels and area under the curve on continuous glucose monitoring.

RESULTS

Changes in HbA1c values, body weight, and total insulin dose declined in the treatment group compared with the control group (bootstrapped, P <or= .02 for each). The treatment group also demonstrated lower average dinner area under the curve (P = .02) and lower maximum breakfast (P = .03) and dinner (P = .02) postprandial blood glucose values.

CONCLUSIONS

Pramlintide can help some adolescents to decrease postprandial hyperglycemia, HbA1c values, body weight, and insulin dosages. Additional large-scale trials should now be considered.

Diabetes mellitus and gastric emptying: questions and issues in clinical practice

It is long known that both type 1 and type 2 diabetes can be associated with changes in gastric emptying; a number of publications have linked diabetes to delayed gastric emptying of variable severity and often with poor relationship to gastrointestinal symptomatology. In contrast, more recent studies have reported accelerated gastric emptying when adjusted for glucose concentration in patients with diabetes, indicating a reciprocal relationship between gastric emptying and ambient glucose concentrations. This review proposes that gastroparesis or gastroparesis diabeticorum, a severe condition characterized by a significant impairment of gastric emptying accompanied by severe nausea, vomiting, and malnutrition, is often overdiagnosed and not well contrasted with delays in gastric emptying. The article offers a clinically relevant definition of gastroparesis that should help differentiate this rare condition from (often asymptomatic) delays in gastric emptying. The fact that delayed gastric emptying can also be observed in non-diabetic individuals under experimental conditions in which hyperglycaemia is artificially induced suggests that a delay in gastric emptying rate when blood glucose concentrations are high is actually an appropriate physiological response to hyperglycaemia, slowing further increases in blood glucose. The article discusses the strengths and weaknesses of various methodologies for assessing gastric emptying, especially with respect to the diabetes population, and reviews newer diabetes therapies that decelerate the rate of gastric emptying. These therapies may be a beneficial tool in managing postprandial hyperglycaemia because they attenuate rapid surges in glucose concentrations by slowing the delivery of meal-derived glucose.

Reducing postprandial hyperglycemia with adjuvant premeal pramlintide and postmeal insulin in children with type 1 diabetes mellitus

OBJECTIVE

The purpose of this study was to determine the effect of adjuvant premeal pramlintide with postmeal insulin on postprandial hyperglycemia in children with type 1 diabetes mellitus (T1DM).

METHODS

Eight adolescents with T1DM on intensive insulin therapy participated in an open-label, non-randomized, crossover study, comparing postprandial glucose excursions in study A (prescribed insulin regimen and given premeal) vs. study B (pramlintide + insulin). Prandial insulin dose for study B was decreased by 20% and given postmeal, while pramlintide was given just before the meal. Blood glucose (BG), glucagon, and pramlintide concentrations were measured basally and at timed intervals during a 300-min study period.

RESULTS

Postprandial incremental BG for the duration of the study was reduced in study B vs. study A with AUC((-60 to 300 min)) (area under the curve) at 6600 +/- 2371 vs. 20 230 +/- 3126 mg/dL/min (367 +/- 132 vs. 1124 +/- 174 mmol/L/min) (p < 0.001). Glucagon concentration was suppressed for approximately 120 min following administration of 30 microg of pramlintide and postmeal insulin (p < 0.003). No severe hypoglycemic episodes were experienced in this study.

CONCLUSIONS

Postprandial hyperglycemia is considerably reduced in adolescents with T1DM when treated with fixed-dose premeal pramlintide, and precisely calculated postmeal insulin, without significant side effects.

New potential adjuncts to treatment of children with type 1 diabetes mellitus

Insulin administration is the primary therapy for type 1 diabetes mellitus (T1DM). Current available insulin therapies do not successfully enable children with T1DM to reach glycemic goals without side effects such as hypoglycemia and weight gain. Pramlintide is a synthetic analog of human amylin that acts in conjunction with insulin to delay gastric emptying and inhibit the release of glucagon and is indicated for use in patients with type 1 and type 2 diabetes. Recent studies in adult patients have examined the role of glucagon-like peptide 1 (GLP-1) and agents that bind to its receptor in type 1 diabetes. It is hypothesized that a major component of the glycemic effect is attributable to the known action of GLP-1 to delay gastric emptying and to inhibit glucagon secretion. Further studies with the use of amylin analogs and long-acting GLP-1 agonists as congeners with insulin in T1DM are indicated in children. In recent years, our better understanding of the pathophysiology of diabetes has led to the development of new therapies for diabetes. This article reviews the potential use of these newer pharmacologic agents as adjunctive therapy in T1DM in children and adolescents.

Review of pramlintide as adjunctive therapy in treatment of type 1 and type 2 diabetes

Pramlintide (Symlin^®), a synthetic analog of a neurohormone amylin, was approved by the US Food and Drug Administration for use along with premeal insulin in patients with type 1. In patients with type 2 diabetes, pramlintide is approved for addition to premeal insulin in those patients who are either only on premeal insulin or those receiving the combination of insulin and metformin and/or a sulfonylurea. This article reviews the pharmacology, pharmacokinetics, dosing, clinical trials, safety, contraindications, and drug interactions of pramlintide therapy. A search for published clinical trials and therapeutic reviews in the English language was done in the following databases: Iowa Drug Information Service (1966 to July 2008), MEDLINE (1966 to July 2008), and International Pharmaceutical Abstracts (1970 to July 2008). Pramlintide and amylin were used as keywords and title words. References of key articles were also reviewed to identify additional publications. Amylin is a 37 amino acid peptide neurohormone cosecreted from the beta cells of the pancreas, along with insulin, in response to meals. Amylin lowers serum glucose by decreasing glucagon release, slowing gastric emptying and decreasing food intake. Pramlintide, a synthetic analog of amylin, reduces 2-hour postprandial blood glucose between 3.4 and 5 mmol/L, reduces A1C by 0.2% to 0.7% and has no effect on fasting glucose levels. The use of pramlintide was associated with up to a 1.6 kg weight loss. Nausea was the most commonly reported adverse event. Pramlintide is an amylin analog that was FDA approved for the treatment of type 1 and type 2 diabetes. Its use results in modest reduction of A1C and the most frequent side effects are hypoglycemia and nausea.

Impaired hyperglycemia-induced delay in gastric emptying in patients with type 1 diabetes deficient for islet amyloid polypeptide

OBJECTIVE

Slowing of gastric emptying by hyperglycemia, a physiological response to minimize postprandial hyperglycemia, may be impaired in patients with type 1 diabetes. The causes and consequences on glucose homeostasis are unknown.

RESEARCH DESIGN AND METHODS

Consequences of euglycemia- and hyperglycemia-induced changes in gastric emptying on postprandial glucose fluxes and excursions were studied in 10 healthy subjects and 15 type 1 diabetic subjects after ingestion of a mixed meal using the double isotope approach ([6,6-(2)H(2)] and [1-(13)C]glucose) and scintigraphic measurements of gastric emptying.

RESULTS

Gastric emptying was greater in type 1 diabetic subjects (90-120 min, P < 0.03), and 50% retention times were comparable in healthy subjects and type 1 diabetic subjects (167 +/- 8 vs. 152 +/- 10, P = 0.32). Hyperglycemia markedly delayed gastric emptying in healthy subjects but did not alter it in type 1 diabetic subjects (50% retention time 222 +/- 18 vs. 167 +/- 8 min, P = 0.003 and 148 +/- 9 vs. 152 +/- 10 min, P = 0.51). Plasma islet amyloid polypeptide (IAPP) increased approximately fourfold in healthy subjects (P < 0.001), whereas it was undetectable in type 1 diabetic subjects. IAPP replacement, using the analog pramlintide, in type 1 diabetic subjects slowed gastric emptying to a comparable extent, as did hyperglycemia in healthy subjects (P < 0.14), and greatly reduced postprandial hyperglycemia (P < 00.1). Meal-derived glucose appearance in plasma (10.7 +/- 0.5 vs. 6.8 +/- 0.7 mumol . kg(-1) . min(-1), P < 0.001) was reduced, and splanchnic glucose sequestration increased (14.0 +/- 3.0 vs. 25.0 +/- 6.0%, P = 0.04).

CONCLUSIONS

In patients with type 1 diabetes the ability to delay gastric emptying in response to hyperglycemia is impaired. This impairment contributes to exaggerated rates of meal-derived glucose appearance and, ultimately, postprandial glucose excursions.

Diabetes distress and its association with clinical outcomes in patients with type 2 diabetes treated with pramlintide as an adjunct to insulin therapy

OBJECTIVE

This study was designed to assess diabetes-related distress and its association with clinical outcomes in patients with type 2 diabetes using basal insulin who were treated with pramlintide.

METHODS

In a 16-week, double-blind, placebo-controlled study 211 patients using insulin glargine with or without oral antidiabetes agents were randomized to addition of pramlintide or placebo. Clinical outcomes (change in A1C, postprandial glucose, daily basal insulin dose, and weight) and during-trial hypoglycemia were assessed, along with the Diabetes Distress Scale (DDS). The DDS assesses overall diabetes distress and four subdomains: regimen distress (RD), emotional burden (EB), interpersonal distress (ID), and physician-related distress (PD). Hierarchical, stepwise multiple regression was used to assess the association of clinical outcomes and during-trial hypoglycemia with DDS score changes during the study.

RESULTS

Pramlintide use was associated with a significant reduction in total DDS and RD, but only among those above the median of distress at baseline. Across treatment groups, reduction in basal insulin dose was linked to a drop in total DDS, RD, EB, and ID, reduction in postprandial glucose was associated with reduced total DDS and ID, and reduction in A1C was associated with reduced EB and RD. PD was not associated with hypoglycemia or any clinical outcome. Reduction in weight and incidence of hypoglycemia were not associated with any DDS measure.

CONCLUSIONS

Pramlintide use reduced diabetes-related distress among those with high levels of distress at baseline, and better clinical outcomes were associated with improvements in several domains of diabetes-related distress. Efforts should be made to enhance these potential benefits of treatment.

Pramlintide, the synthetic analogue of amylin: physiology, pathophysiology, and effects on glycemic control, body weight, and selected biomarkers of vascular risk

Pramlintide is a synthetic version of the naturally occurring pancreatic peptide called amylin. Amylin and pramlintide have similar effects on lowering postprandial glucose, lowering postprandial glucagon and delaying gastric emptying. Pramlintide use in type 1 and insulin requiring type 2 diabetes mellitus (DM) is associated with modest reductions in HbA1c often accompanied by weight loss. Limited data show a neutral effect on blood pressure. Small studies suggest small reductions in LDL-cholesterol in type 2 DM and modest reductions in triglycerides in type 1 DM. Markers of oxidation are also reduced in conjunction with reductions in postprandial glucose. Nausea is the most common side effect. These data indicate that pramlintide has a role in glycemic control of both type 1 and type 2 DM. Pramlintide use is associated with favorable effects on weight, lipids and other biomarkers for atherosclerotic disease.

Glucose homeostasis and the gastrointestinal tract: insights into the treatment of diabetes

The gastrointestinal tract is increasingly viewed as a critical organ in glucose metabolism because of its role in delivering glucose to the circulation and in secreting multiple glucoregulatory hormones that, in concert with insulin and glucagon, regulate glucose homeostasis. Under normal conditions, a complex interplay of these hormones acts to maintain plasma glucose within a narrow range despite large variations in the availability of glucose, particularly during transition from the fasting to fed state. In the fed state, the rate at which nutrients are passed from the stomach to the duodenum, termed gastric emptying rate, is a key determinant of postprandial glucose flux. In patients with diabetes, the regulation of glucose metabolism is disrupted resulting in fasting and postprandial hyperglycaemia. Elucidation of the role of the gastrointestinal tract, gut-derived glucoregulatory peptides and gastric emptying rate offers a new perspective on glucose homeostasis and the respective importance of these factors in the diabetes state. This review will highlight the importance of the gastrointestinal tract in playing a key role in glucose homeostasis, particularly in the postprandial period, and the role of established or new therapies that either leverage or modify gastrointestinal function to improve glycaemic state.

The role of prandial pramlintide in the treatment of adolescents with type 1 diabetes

Pramlintide, a synthetic analog of amylin, improves postprandial hyperglycemia. We compared subcutaneous (s.c.) pramlintide injection with square wave pramlintide infusion in adolescents with type 1 diabetes (T1DM). Eight subjects with T1DM underwent two randomized studies. Subcutaneous pramlintide (dose = 5 microg/unit of insulin) bolus, was given one time and another time, the same dose was given as a 120-min s.c. infusion. Insulin dose was constant between studies. Gastric emptying was assessed with oral acetaminophen and [l-13C]glucose in meal. Plasma glucagon, pramlintide, and insulin concentrations were measured. Insulin concentrations (p < 0.99) between pramlintide injection versus infusion were similar; however, glucose concentrations were different (p < 0.0001), with the absence of hypoglycemia during pramlintide infusion [AUC (0-120 min) -0.07 +/- 0.2 versus 1.05 +/- 0.24 mg * h/dL (p < 0.0088)]. Insulin-only administration resulted in postprandial hyperglycemia and late postprandial hypoglycemia (p < 0.0001). Two subjects experienced hypoglycemia with pramlintide injection. Pramlintide bolus caused pronounced glucagon suppression (p < 0.0003) and delayed gastric emptying as ([13CO2] p < 0.0003 and acetaminophen p < 0.01) compared with infusion. We conclude that pramlintide bolus may result in an increase in risk of immediate postprandial hypoglycemia. Further modifications in pramlintide delivery are indicated before it can be safely used in children.

Pramlintide acetate injection for the treatment of type 1 and type 2 diabetes mellitus

BACKGROUND

Amylin is a hormone cosecreted with insulin by the beta cells of the pancreas. It suppresses postprandial glucagon secretion and slows gastric emptying. Pramlintide acetate is an amylin analogue that was approved by the US Food and Drug Administration in March 2005.

OBJECTIVE

This article reviews the current primary literature on the clinical efficacy and tolerability of pramlintide injection in the treatment of type 1 and type 2 diabetes mellitus (DM). Among other topics covered are the pharmacokinetics, pharmacodynamics, and dosing and administration of pramlintide.

METHODS

Pertinent English-language articles were identified through a search of MEDLINE (1966-January 2007), International Pharmaceutical Abstracts (1970-present), Database of Abstracts of Reviews of Effectiveness (1995-January 2007), Cochrane Database of Systematic Reviews (1995-January 2007), and EMBASE Drugs & Pharmacology (1991-1st quarter 2007). The search terms included pramlintide, amylin, gastric emptying, pharmacokinetic, pharmacoeconomic, postprandial hyperglycemia, and glucagon. Articles were selected for review if they described studies having a randomized, double-blind, controlled design and included glycosylated hemoglobin (HbA(1c)) as an end point.

RESULTS

Pramlintide is administered subcutaneously in the abdominal area or thigh immediately before each main meal to achieve maximal reductions in post-prandial glucose excursions. Its C(max) is reached within 20 minutes, and its t(1/2) is 48 minutes. Metabolism is primarily via the kidneys. Pramlintide therapy was associated with inhibition of postprandial glucagon secretion in 24 patients with type 2 DM; prolonged gastric emptying in 11 patients with type 1 DM; a 23% reduction in total energy intake in 11 patients with type 2 DM; and a reduction in markers of oxidative stress in 18 patients with type 1 DM (all, P <- 0.05 vs placebo). In two 52-week studies in patients with type 1 DM, the groups that received pramlintide 30 to 60 microg QID (n = 243), 60 microg TID (n = 164), and 60 microg QID (n = 161) had respective 0.39%, 0.29%, and 0.34% reductions in HbA(1c) and 0.5-, 0.3-, and 0.6-kg reductions in body weight, respectively (all, P < 0.05 vs placebo). In two 52-week studies in patients with type 2 DM, the groups that received pramlintide 120 microg BID (n = 166) and 150 microg TID (n = 144) had respective 0.62% and 0.6% reductions in HbA(1c) and 1.4- and 1.3-kg reductions in body weight (all, P < 0.05 vs placebo). Hypoglycemia, nausea, vomiting, and anorexia were the most frequently reported (>/=10% occurrence) adverse events in patients receiving pramlintide compared with placebo. These events were mild to moderate and occurred more frequently during the first month of therapy.

CONCLUSIONS

Pramlintide therapy was associated with reductions in HbA(1c) and body weight in four 52-week studies in patients with type 1 DM and type 2 DM. Hypoglycemia, nausea, vomiting, and anorexia were the most frequently occurring adverse events, particularly during the first month of therapy. Pramlintide was associated with reductions in measures of oxidative stress, but studies are needed to evaluate the effects of this agent on DM-related complications.