Exenatide once weekly slows gastric emptying of solids and liquids in healthy, overweight people at steady-state concentrations

Perioperative management of long-acting glucagon-like peptide-1 (GLP-1) receptor agonists: concerns for delayed gastric emptying and pulmonary aspiration

Prescriptions and use of glucagon-like peptide-1 (GLP-1) receptor agonists are increasing dramatically, as indications are expanding from the treatment of diabetes mellitus to weight loss for people with obesity. As GLP-1 receptor agonists delay gastric emptying, perioperative healthcare practitioners could be concerned about an increased risk for pulmonary aspiration during general anaesthesia. We summarise relevant medical literature and provide evidence-based recommendations for perioperative care for people taking GLP-1 receptor agonists. GLP-1 receptor agonists delay gastric emptying; however, ongoing treatment attenuates this effect. The risk of aspiration during general anaesthesia is unknown. However, we advise caution in patients who recently commenced on GLP-1 receptor agonists. After over 12 weeks of treatment, standard fasting times likely suffice to manage the risk of pulmonary aspiration for most otherwise low-risk patients.

Glucagon-like peptide-1 receptor agonists modestly reduced blood pressure among patients with and without diabetes mellitus: A meta-analysis and meta-regression

AIM

The cardiovascular benefits provided by glucagon-like peptide-1 receptor agonists (GLP-1RAs) extend beyond weight reduction and glycaemic control. One possible mechanism may relate to blood pressure (BP) reduction. We aim to quantify the BP-lowering effects of GLP1-RAs.

METHODS

A comprehensive database search for placebo-controlled randomized controlled trials on GLP-1RA treatment was conducted until December 2023. Data extraction and quality assessment were carried out, employing a robust statistical analysis using a random effects model to determine outcomes with a mean difference (MD) in mmHg and 95% confidence intervals (CIs). The primary endpoint was the mean difference in systolic BP (SBP) and diastolic BP. Subgroup analyses and meta-regressions were done to account for covariates.

RESULTS

Compared with placebo, GLP-1RAs modestly reduced SBP [semaglutide: MD -3.40 (95% CI -4.22 to -2.59, p < .001); liraglutide: MD -2.61 (95% CI -3.48 to -1.74, p < .001); dulaglutide: MD -1.46 (95% CI -2.20 to -0.72, p < .001); and exenatide: MD -3.36 (95% CI -3.63 to -3.10, p < .001)]. This benefit consistently increased with longer treatment durations. Diastolic BP reduction was only significant in the exenatide group [MD -0.94 (95% CI -1.78 to -0.1), p = .03]. Among semaglutide cohorts, mean changes in glycated haemoglobin and mean changes in body mass index were directly associated with SBP reduction.

CONCLUSION

Patients on GLP-1RA experienced modest SBP lowering compared with placebo. This observed effect was associated with weight/body mass index reduction and better glycaemic control, which suggests that BP-lowering is an indirect effect of GLP-1RA and unlikely to be responsible for the benefits.

Glucagon-like-peptide-1 receptor agonists and the management of type 2 diabetes-backwards and forwards

This editorial is stimulated by the article by Alqifari et al published in the World Journal of Diabetes (2024). Alqifari et al focus on practical advice for the clinical use of glucagon-like-peptide-1 (GLP-1) receptor agonists (GLP-1RAs) in the management of type 2 diabetes and this editorial provides complementary information. We initially give a brief historical perspective of the development of GLP-1RAs stimulated by recognition of the 'incretin effect', the substantially greater insulin increase to enteral when compared to euglycaemic intravenous glucose, and the identification of the incretin hormones, GIP and GLP-1. In addition to stimulating insulin, GLP-1 reduces postprandial glucose levels by slowing gastric emptying. GLP-1RAs were developed because native GLP-1 has a very short plasma half-life. The majority of current GLP-1RAs are administered by subcutaneous injection once a week. They are potent in glucose lowering without leading to hypoglycaemia, stimulate weight loss in obese individuals and lead to cardiovascular and renal protection. The landscape in relation to GLP-1RAs is broadening rapidly, with different formulations and their combination with other peptides to facilitate both glucose lowering and weight loss. There is a need for more information relating to the effects of GLP-1RAs to induce gastrointestinal symptoms and slow gastric emptying which is likely to allow their use to become more effective and personalised.

Practical guide: Glucagon-like peptide-1 and dual glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1 receptor agonists in diabetes mellitus

In 2005, exenatide became the first approved glucagon-like peptide-1 receptor agonist (GLP-1 RA) for type 2 diabetes mellitus (T2DM). Since then, numerous GLP-1 RAs have been approved, including tirzepatide, a novel dual glucose-dependent insulinotropic polypeptide (GIP)/GLP-1 RA, which was approved in 2022. This class of drugs is considered safe with no hypoglycemia risk, making it a common second-line choice after metformin for treating T2DM. Various considerations can make selecting and switching between different GLP-1 RAs challenging. Our study aims to provide a comprehensive guide for the usage of GLP-1 RAs and dual GIP and GLP-1 RAs for the management of T2DM.

Chronic GLP1 therapy reduces postprandial IL6 in obese humans with prediabetes

Single-dose glucagon-like peptide 1 (GLP1) therapy increases postprandial plasma IL6 levels in prediabetic, obese humans. GLP1-IL6 interactions underly multiple antidiabetic effects, but these may differ after acute versus chronic therapy. This study examines postprandial effects of GLP1 after chronic therapy. Seven humans (six Black) with prediabetes and obesity completed 6 weeks of exenatide extended release therapy. Then subjects returned for pre- and post-meal measurements of plasma IL6, GLP1, glucagon, and related inflammatory markers. Weight, which was measured before and after therapy, did not change. Plasma IL6 decreased from baseline to postmeal state ( = 0.016), with decreases in free fatty acids (P < 0.001) and increases in insulin (P = 0.002), glucose (P < 0.0001), triglycerides (P = 0.0178), and glucagon (P = 0.018). Baseline GLP1 levels matched 6 weeks of therapy. The fall in postprandial plasma IL6, which contrasts with the increase after acute therapy, highlights the need for more investigation regarding the mechanisms of acute versus chronic GLP1-IL6 signaling.

Ultrasound evaluation of gastric emptying time of standardized high-calorie liquid meals in healthy adults: A double-blind cross-over randomized study

BACKGROUND AND AIMS

Commercially available high-calorie drinks containing fat and protein can be used as dietary supplements in surgical patients. According to preoperative fasting guidelines, high-calorie drinks are non-clear fluids and should not be consumed 6 h before elective procedures. The aim of this study was to evaluate the gastric emptying time of commercially available high-calorie drink formulations in healthy adults using gastric ultrasound.

METHODS

25 healthy adult volunteers were included in this double-blind, cross-over prospective study. On three study sessions, fasted volunteers ingested one of the three study products: a solution of 75 g of glucose in 200 ml of water, a fat-free liquid meal, and a nutritionally complete liquid meal with equal volume and energy content. Gastric ultrasound examinations were performed to evaluate the gastric contents qualitatively and the volume of the gastric contents was calculated from the cross-sectional area of the gastric antrum measured in right lateral position by using a validated model. Repeated gastric ultrasounds were performed at baseline and half-hourly after ingesting the products in supine and right lateral position until the criteria for an empty stomach were met.

RESULTS

The glucose solution and the standard fat-free high-calorie drink with the same caloric content had a median gastric emptying time of 150 min. The nutritionally complete liquid meal had a median gastric emptying time of 180 min. Gastric emptying was complete in all participants before 6 h had elapsed since ingesting the study products.

CONCLUSIONS

High calorie liquid meals have a gastric emptying time longer than the recommended fasting time for clear fluids, but shorter than the recommended fasting time for solids in healthy adults.

The role of gastric function in control of food intake (and body weight) in relation to obesity, as well as pharmacological and surgical interventions

PURPOSE

The objectives of this review are to summarize the role of gastric motor functions in the development of satiation (defined broadly as postprandial fullness) and satiety (reduced appetite or postponing desire to eat after a meal) and their impact on weight change. The specific topics are the methods of measurement of gastric emptying and accommodation and their impact on food intake, satiation, and satiety. A second focus contrasts bariatric surgery to endoscopic gastroplasty that alter gastric emptying and incretin responses in markedly divergent manners.

BACKGROUND

The hormone, GLP-1, retards gastric emptying and increases gastric accommodation through vagally-mediated effects. Indeed, these effects provide the basis for the association of altered gastric emptying in the appetite and weight loss responses to pharmacological interventions particularly by those acting on receptors of incretin agonists such as liraglutide and the dual agonists, tirzepatide and cotadutide, all of which retard gastric emptying. In fact, retardation of gastric emptying and gastrointestinal adverse effects have been shown to contribute in part to the weight loss in response to this class of pharmacological agents.

SUMMARY

The motor functions of the stomach are relevant to postprandial fullness and to interventions aimed at weight loss in people with obesity.

Review article: Pharmacologic management of obesity - updates on approved medications, indications and risks

BACKGROUND

Obesity has reached epidemic proportions, with >40% of the US population affected. Although traditionally managed by lifestyle modification, and less frequently by bariatric therapies, there are significant pharmacological advancements.

AIMS

To conduct a narrative review of the neurohormonal and physiological understanding of weight gain and obesity, and the development, clinical testing, indications, expected clinical outcomes, and associated risks of current FDA-approved and upcoming anti-obesity medications (AOMs).

METHODS

We conducted a comprehensive review in PubMed for articles on pathophysiology and complications of obesity, including terms 'neurohormonal', 'obesity', 'incretin', and 'weight loss'. Next, we searched for clinical trial data of all FDA-approved AOMs, including both the generic and trade names of orlistat, phentermine/topiramate, bupropion/naltrexone, liraglutide, and semaglutide. Additional searches were conducted for tirzepatide and retatrutide - medications expecting regulatory approval. Searches included combinations of terms related to mechanism of action, indications, side effects, risks, and future directions.

RESULTS

We reviewed the pathophysiology of obesity, including specific role of incretins and glucagon. Clinical data supporting the use of various FDA-approved medications for weight loss are presented, including placebo-controlled or, when available, head-to-head trials. Beneficial metabolic effects, including impact on liver disease, adverse effects and risks of medications are discussed, including altered gastrointestinal motility and risk for periprocedural aspiration.

CONCLUSION

AOMs have established efficacy and effectiveness for weight loss even beyond 52 weeks. Further pharmacological options, such as dual and triple incretins, are probable forthcoming additions to clinical practice for combating obesity and its metabolic consequences such as metabolic dysfunction-associated steatotic liver disease.

Effects of GLP-1 and Other Gut Hormone Receptors on the Gastrointestinal Tract and Implications in Clinical Practice

Agonists targeting the receptors of incretin hormones, glucagon-like peptide-1 and glucose-dependent insulinotropic peptide, have been well established for the treatment of type 2 diabetes mellitus. There is increasing awareness that gastroenterologists and hepatologists should be treating obesity when patients present to their clinics. In addition, gastroenterologists and hepatologists should be aware of the effects of these classes of medications prescribed by other providers. Therefore, given the widespread use of incretin agonists for obesity treatment and weight loss, it is important to recognize their effects in the gastrointestinal tract, which could constitute significant benefits in weight loss and cardiometabolic benefits, but can be associated with adverse effects that constitute a potential barrier to their use, particularly at higher doses. Multiple studies reviewed in this article document the diverse effects of these drugs on the glucagon-like peptide-1 receptors that are widely expressed in the human body, including the nervous system modulating appetite, the gastrointestinal tract modifying gastric emptying, and lipid metabolism regulation leading to reduction in fat deposition. The objective of this review is to summarize the mechanism of action of incretin receptor agonists, their effects in the gastrointestinal tract, and implications in clinical practice, particularly in the practice of gastroenterology, endoscopy, and surgery.

GLP-1RAs caused gastrointestinal adverse reactions of drug withdrawal: a system review and network meta-analysis

Background

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) significantly reduce postprandial blood glucose, inhibit appetite, and delay gastrointestinal emptying. However, it is controversial that some patients are intolerant to GLP-1RAs.

Methods

PubMed, Embase, Web of Science, and Cochrane Library were searched for randomized controlled trials (RCTs) using GLP-1RAs with documented withdrawal due to gastrointestinal adverse reactions (GI AEs) from their inception to September 28, 2022. After extracting the information incorporated into the studies, a random-effects network meta-analysis was performed within a frequentist framework.

Results

64 RCTs were finally enrolled, which included six major categories of the GLP-1RA. The sample size of the GLP-1RAs treatment group was 16,783 cases. The risk of intolerable gastrointestinal adverse reactions of Liraglutide and Semaglutide was higher than that of Dulaglutide. Meanwhile, the higher the dose of the same GLP-1RA preparation, the more likely to cause these adverse reactions. These intolerable GI AEs were not significantly related to drug homology or formulations and may be related to the degree of suppression of the appetite center.

Conclusion

Dulaglutide caused the lowest intolerable GI AEs, while Liraglutide and Semaglutide were the highest. For Semaglutide, the higher the dose, the more likely it is to drive GI AEs. Meanwhile, the risk of these GI AEs is independent of the different formulations of the drug. All these findings can effectively guide individualized treatment.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022359346, identifier CRD42022359346.

The 'early' postprandial glucagon response is related to the rate of gastric emptying in type 2 diabetes

Gastric emptying (GE) is a major determinant of the postprandial glycemic and insulinemic responses in health and type 2 diabetes (T2D). However, the effect of GE on the postprandial glucagon response, which is characteristically augmented in T2D, is unknown. This study examined the relationship between plasma glucagon and GE of a standardized mixed meal in individuals with well-controlled T2D. 89 individuals with T2D (HbA1c 6.6 ± 0.1%) consumed a mashed potato meal labeled with 100 µL ¹³C-octanoic acid between 0 and 5 min. Venous blood was sampled frequently over 4 h for measurements of blood glucose and plasma glucagon. The gastric half-emptying time (T50) was calculated by quantification of ¹³C in the breath. Blood glucose peaked at t = 90 min after the meal. Plasma glucagon increased to a peak at t = 30 min and then decreased to a nadir at t = 180 min. The T50 was 68.3 ± 1.6 min. The incremental area under the plasma glucagon curve between t = 0-30 min (glucagon iAUC_0-30 min) was related inversely to the T50 (r = -0.23, P = 0.029), while the increase in blood glucose at t = 30 min was related directly to the plasma glucagon iAUC_0-30 min (r = 0.25, P = 0.018). Accordingly, individuals with relatively faster GE exhibited higher postprandial glucagon and glucose levels (ANOVA: P<0.01 for each). In well-controlled T2D, the early postprandial glucagon response to a mixed meal is related to the rate of GE, and predictive of the initial glycemic response. These observations suggest that a reduction in plasma glucagon may contribute to the effect of dietary and pharmacological strategies which reduce postprandial glycemia in T2D by slowing GE.

Factors associated with successful weight loss after liraglutide treatment for obesity

AIM

To identify patient factors, including gastrointestinal functions, that are predictive or associated with weight loss in response to once-daily 3 mg liraglutide administered subcutaneously (SQ) or placebo in obesity.

METHODS

One hundred and thirty-six obese adults (87% female) were randomized in a placebo-controlled, 16-week trial of liraglutide, escalated to 3 mg administered SQ daily. Gastrointestinal functions were measured at baseline and 16 weeks: gastric emptying of solids (GET1/2 ); fasting and postprandial gastric volumes; kcal ingested during ad libitum buffet meal and the nutrient drink test. GET1/2 was also measured at 5 weeks. A multiple variable regression model examined variables associated with weight loss of more than 4 kg at 16 weeks. A parsimonious model using backward selection identified the final model.

RESULTS

Weight loss of more than 4 kg at 16 weeks occurred in 71% of liraglutide- and 16% of placebo-treated patients. In all participants combined, parameters univariately associated with a weight loss of more than 4 kg were GET1/2 at 5 and 16 weeks, weight loss at 5 weeks and kcal intake during the buffet meal at 16 weeks. The final parsimonious model (area under the receiver operator characteristics [AUROC] curve = 0.832) identified that factors associated with more than 4-kg weight loss were GET1/2 at 5 weeks (OR = 2.505; 95% CI: 1.57-3.997) per 50 minutes and kcal intake during ad libitum meal at 16 weeks (OR = 0.721; 95% CI: 0.602-0.864) per 100 kcal. Among only the 60 liraglutide-treated subjects, kcal intake at 16 weeks was associated with 4-kg weight loss (AUROC = 0.757).

CONCLUSIONS

Slower GET1/2 and weight loss at 5 weeks predicted a weight loss of more than 4 kg at 16 weeks in all participants. Among liraglutide-treated adults, weight loss of more than 4 kg was associated with ad libitum meal kcal intake at 16 weeks.

Glucagon-like peptide-1 receptor agonists as adjunctive treatment for type 1 diabetes: Renewed opportunities through tailored approaches?

Exogenous insulin has been the mainstay treatment for individuals living with type 1 diabetes (T1D). Although there has been tremendous growth in both pharmacological and technological advancements, insulin monotherapy has proven to be insufficient for maintaining optimal glycaemic targets for most adults with T1D. At present, there is still no breakthrough for the treatment of T1D. Adjunctive pharmacotherapies might therefore complement insulin management to achieve better glycaemic control, while possibly offering additional benefits. Recent interest in re-purposing glucagon-like peptide-1 receptor agonists (GLP-1RAs), a leading antihyperglycaemic medication class approved for type 2 diabetes, has prompted the field to seek extended potential for the T1D population. The adjunctive use of GLP-1RAs has been at the forefront of T1D research, albeit with some conflicting trial findings to date. However, the potential of GLP-1 agonism for T1D may have been underestimated, possibly from missed opportunities or categorized effects. Moreover, some GLP-1RAs have demonstrated extra-pancreatic potential with emerging multi-organ protection involving the heart, kidneys, liver and brain in varied cohorts, which may bode well for the growing T1D profile of comorbid complications. This narrative review aims to summarize and critically appraise the current evidence-based literature from large-scale randomized controlled trials and closed-loop system pilot studies that examined GLP-1RAs as adjunctive therapy for T1D. Furthermore, we outline uncharted opportunities with GLP-1 agonism using versatile approaches in selected T1D populations that may inspire and re-direct future research in this field.

Fighting type 2 diabetes: Formulation strategies for peptide-based therapeutics

Diabetes mellitus is a major health problem with increasing prevalence at a global level. The discovery of insulin in the early 1900s represented a major breakthrough in diabetes management, with further milestones being subsequently achieved with the identification of glucagon-like peptide-1 (GLP-1) and the introduction of GLP-1 receptor agonists (GLP-1 RAs) in clinical practice. Moreover, the subcutaneous delivery of biotherapeutics is a well-established route of administration generally preferred over the intravenous route due to better patient compliance and prolonged drug absorption. However, current subcutaneous formulations of GLP-1 RAs present pharmacokinetic problems that lead to adverse reactions and treatment discontinuation. In this review, we discuss the current challenges of subcutaneous administration of peptide-based therapeutics and provide an overview of the formulations available for the different routes of administration with improved bioavailability and reduced frequency of administration.

Medication-Induced Gastroparesis: A Case Report

Gastroparesis is a commonly diagnosed gastrointestinal disorder with a high prevalence globally and high disease burden to those afflicted with it. Etiologies are variable with idiopathic and diabetes being the most common causes of gastroparesis. Management of gastroparesis depends on the etiology, and accurate diagnosis is required for better targeted therapy. Medication-induced gastroparesis is reversible, and discontinuing the medication is generally curative. This case report discusses 2 cases of medication-induced gastroparesis which were initially diagnosed as diabetic gastroparesis, and thorough history taking revealed the cause to be medication induced. Repeat studies following medication discontinuation revealed improvement in symptoms and resolution of gastroparesis. Further research needs to be done to assess the frequency of misdiagnosing diabetic patients with gastroparesis due to medications, specifically glucagon-like peptide-1 receptor agonists which are increasingly being used in diabetics.

Potential for Gut Peptide-Based Therapy in Postprandial Hypotension

Postprandial hypotension (PPH) is an important and under-recognised disorder resulting from inadequate compensatory cardiovascular responses to meal-induced splanchnic blood pooling. Current approaches to management are suboptimal. Recent studies have established that the cardiovascular response to a meal is modulated profoundly by gastrointestinal factors, including the type and caloric content of ingested meals, rate of gastric emptying, and small intestinal transit and absorption of nutrients. The small intestine represents the major site of nutrient-gut interactions and associated neurohormonal responses, including secretion of glucagon-like peptide-1, glucose-dependent insulinotropic peptide and somatostatin, which exert pleotropic actions relevant to the postprandial haemodynamic profile. This review summarises knowledge relating to the role of these gut peptides in the cardiovascular response to a meal and their potential application to the management of PPH.

Gastric Sensory and Motor Functions and Energy Intake in Health and Obesity-Therapeutic Implications

Sensory and motor functions of the stomach, including gastric emptying and accommodation, have significant effects on energy consumption and appetite. Obesity is characterized by energy imbalance; altered gastric functions, such as rapid gastric emptying and large fasting gastric volume in obesity, may result in increased food intake prior to reaching usual fullness and increased appetite. Thus, many different interventions for obesity, including different diets, anti-obesity medications, bariatric endoscopy, and surgery, alter gastric functions and gastrointestinal motility. In this review, we focus on the role of the gastric and intestinal functions in food intake, pathophysiology of obesity, and obesity management.

Effects of GLP-1 and Its Analogs on Gastric Physiology in Diabetes Mellitus and Obesity

The processing of proglucagon in intestinal L cells results in the formation of glucagon, GLP-1, and GLP-2. The GLP-1 molecule becomes active through the effect of proconvertase 1, and it is inactivated by dipeptidyl peptidase IV (DPP-IV), so that the half-life of endogenous GLP-1 is 2-3 min. GLP-1 stimulates insulin secretion from β cells in the islets of Langerhans. Human studies show that infusion of GLP-1 results in slowing of gastric emptying and increased fasting and postprandial gastric volumes. Retardation of gastric emptying reduces postprandial glycemia. Exendin-4 is a peptide agonist of the GLP-1 receptor that promotes insulin secretion. Chemical modifications of exendin-4 and GLP-1 molecules have been accomplished to prolong the half-life of GLP-1 agonists or analogs. This chapter reviews the effects of GLP-1-related drugs used in treatment of diabetes or obesity on gastric motor functions, chiefly gastric emptying. The literature shows that diverse methods have been used to measure effects of the GLP-1-related drugs on gastric emptying, with most studies using the acetaminophen absorption test which essentially measures gastric emptying of liquids during the first hour and capacity to absorb the drug over 4-6 h, expressed as AUC. The most valid measurements by scintigraphy (solids or liquids) and acetaminophen absorption at 30 or 60 min show that GLP-1-related drugs used in diabetes or obesity retard gastric emptying, and this is associated with reduced glycemia and variable effects on food intake and appetite. GLP-1 agonists and analogs are integral to the management of patients with type 2 diabetes mellitus and obesity. The effects on gastric emptying are reduced with long-acting preparations or long-term use of short-acting preparations as a result of tachyphylaxis. The dual agonists targeting GLP-1 and another receptor (GIP) do not retard gastric emptying, based on reports to date. In summary, GLP-1 agonists and analogs are integral to the management of patients with type 2 diabetes mellitus and obesity, and their effects are mediated, at least in part, by retardation of gastric emptying.

Gastric emptying in health and type 2 diabetes: An evaluation using a 75 g oral glucose drink

AIM

Gastric emptying is a major determinant of the glycaemic response to carbohydrate and is frequently abnormal in type 2 diabetes (T2DM). There is little information about how chronic glycaemic control affects gastric emptying in T2DM. We evaluated gastric emptying of a 75 g glucose drink in community-based patients with T2DM of short duration with good or poor glycaemic control, and compared this to young and older controls.

METHODS

T2DM patients managed by diet and/or metformin, either well-controlled or poorly-controlled, together with young and age-matched older controls without diabetes, consumed a 75 g oral glucose drink containing 150 mg ¹³C-acetate for evaluation of gastric emptying (breath test) and blood glucose over 180 min.

RESULTS

The gastric half-emptying time (T50) was longer in the older than the young non-diabetic subjects (P = 0.041), but shorter in well-controlled T2DM patients than age-matched older controls (P = 0.043). The T50 in poorly-controlled T2DM patients was shorter than in older controls (P = 0.006), but similar to young non-diabetic subjects.

CONCLUSIONS

Gastric emptying of a glucose drink is delayed with ageing, but more rapid in patients with T2DM of relatively short duration, regardless of their glycaemic status. These observations support interventions that slow gastric emptying to improve postprandial glycaemia in these patients with T2DM.

Gut-Based Strategies to Reduce Postprandial Glycaemia in Type 2 Diabetes

Postprandial glycemic control is an important target for optimal type 2 diabetes management, but is often difficult to achieve. The gastrointestinal tract plays a major role in modulating postprandial glycaemia in both health and diabetes. The various strategies that have been proposed to modulate gastrointestinal function, particularly by slowing gastric emptying and/or stimulating incretin hormone GLP-1, are summarized in this review.

Gastrointestinal adverse events with insulin glargine/lixisenatide fixed-ratio combination versus glucagon-like peptide-1 receptor agonists in people with type 2 diabetes mellitus: A network meta-analysis

AIMS

Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are the recommended first injectable therapy in type 2 diabetes. However, long-term persistence is suboptimal and partly attributable to gastrointestinal tolerability, particularly during initiation/escalation. Gradual titration of fixed-ratio combination GLP-1 RA/insulin therapies may improve GLP-1 RA gastrointestinal tolerability. We compared gastrointestinal adverse event (AE) rates for iGlarLixi versus GLP-1 RAs during the first 12 weeks of therapy, including a sensitivity analysis with IDegLira.

MATERIALS AND METHODS

The PICO framework was used to identify studies from MEDLINE, EMBASE and CENTRAL searches using a proprietary, web-based, standardized tool with single data extraction. Gastrointestinal AEs were modelled using a Bayesian network meta-analysis (NMA), using fixed and random effects for each recommended dose (treatment-specific NMA) and class (drug-class NMA).

RESULTS

Treatment-specific NMA included 17 trials (n = 9030; 3665 event-weeks). Nausea rates were significantly lower with iGlarLixi versus exenatide 10 μg twice daily (rate ratio: 0.32; 95% credible interval: 0.15, 0.66), once-daily lixisenatide 20 μg (0.35; 0.24, 0.50) and liraglutide 1.8 mg once daily (0.48; 0.23, 0.98). Rates were numerically, but not statistically, lower versus once-weekly semaglutide 1 mg (0.60; 0.30, 1.23) and dulaglutide 1.5 mg (0.60; 0.29, 1.26), and numerically, but not statistically, higher versus once-weekly exenatide (1.91; 0.91, 4.03). Sensitivity analysis results were similar. In a naïve, pooled analysis, vomiting was lower with iGlarLixi versus other GLP-1 RAs.

CONCLUSIONS

During the first 12 weeks of treatment, iGlarLixi was generally associated with less nausea and vomiting than single-agent GLP-1 RAs. Enhanced gastrointestinal tolerability with fixed-ratio combinations may favour treatment persistence.

Exenatide once weekly combined with metformin reduced glycemic variability in type 2 diabetes by using flash glucose monitoring system

BACKGROUND

Multiple studies demonstrate that fluctuating blood glucose level produces greater damage compared with sustained hyperglycemia. Flash glucose monitoring system is an effective method in documenting blood glucose variability, contributing to better glucose management and reduced hypoglycemic event occurrence.

AIM

To investigate the improvement in glycemic variability (GV), blood glucose level, and metabolic indexes of patients with type 2 diabetes mellitus after combined treatment of exenatide once weekly (EXQW) and metformin.

METHODS

Twenty-five patients with type 2 diabetes mellitus suffering from poor blood glucose control under metformin treatment were recruited. The recruited patients were prescribed with oral metformin only (maintaining a dosage of metformin at ≥ 1500 mg/day) for 2 wk (screening period), and then given EXQW (2 mg, subcutaneous injection) for 12 wk (experimental period). The flash glucose monitoring system was used to document blood glucose values during the screening period and the last 2 wk of the experimental period.

RESULTS

Four patients were excluded for various reasons, yielding a total of 21 patients, including 17 males and 4 females, with an average age of 48.8 years, who completed this study. The estimated glycated hemoglobin, mean blood glucose, fasting and postprandial blood glucose levels, and percentage of blood glucose above 7.8 mmol/L decreased compared to those at baseline (P = 0.003, 0.003, 0.008, 0.010, 0.014, 0.017, and 0.005, respectively), while the percentage of blood glucose between 3.9 and 7.8 mmol/L significantly increased (P = 0.005). Parameters of GV including standard deviation of blood glucose, mean amplitude of glycemic excursions, mean of daily difference, area under the curve difference between percentiles 25 and 75, and area under the curve difference between percentiles 10 and 90 were significantly lower compared to that of baseline (P = 0.017, 0.006, 0.000, 0.024, 0.036, respectively). The durations of blood glucose below 3.9 mmol/L during the day and nocturnal periods significantly increased after treatment (P = 0.041 and 0.028, respectively), but there was no significant increase in severe hypoglycemia (< 3.0 mmol/L) compared with that at baseline (P = 0.207). In addition, some metabolic indicators improved after EXQW treatment.

CONCLUSION

EXQW combined with metformin can effectively improve blood glucose levels, reduce GV, and improve metabolic indicators. However, there is still a risk of nocturnal hypoglycemia, and careful attention should be paid to patients with EXQW treatment.

Role of intestinal glucose absorption in glucose tolerance

Intestinal glucose absorption is integral to postprandial glucose homeostasis. Glucose absorption is dependent on a number of factors, including the exposure of carbohydrate to the mucosa of the upper gastrointestinal tract (determined particularly by the rates of gastric emptying and small intestinal transit), the digestion of complex carbohydrate into monosaccharides, and glucose sensing and transport by the intestinal mucosa. The absorption of glucose in the small intestine is not only a determinant of the appearance of exogenous glucose in the peripheral circulation, but is also coupled to the release of gastrointestinal hormones that in turn influence postprandial glucose metabolism through modulating gastrointestinal motor function, insulin and glucagon secretion, and subsequent energy intake. This review describes the physiology and pathophysiology of intestinal glucose absorption in health and type 2 diabetes, including its relevance to glucose tolerance and the management of postprandial hyperglycaemia.

Gastrointestinal Mechanisms Underlying the Cardiovascular Effect of Metformin

Metformin, the most widely prescribed drug therapy for type 2 diabetes, has pleiotropic benefits, in addition to its capacity to lower elevated blood glucose levels, including mitigation of cardiovascular risk. The mechanisms underlying the latter remain unclear. Mechanistic studies have, hitherto, focused on the direct effects of metformin on the heart and vasculature. It is now appreciated that effects in the gastrointestinal tract are important to glucose-lowering by metformin. Gastrointestinal actions of metformin also have major implications for cardiovascular function. This review summarizes the gastrointestinal mechanisms underlying the action of metformin and their potential relevance to cardiovascular benefits.

Effects of Lixisenatide Versus Liraglutide (Short- and Long-Acting GLP-1 Receptor Agonists) on Esophageal and Gastric Function in Patients With Type 2 Diabetes

OBJECTIVE

Short-acting glucagon-like peptide 1 receptor agonists (GLP-1 RAs) decelerate gastric emptying more than long-acting GLP-1 RAs. Delayed gastric emptying is a risk factor for gastroesophageal reflux disease. We aimed to measure esophageal reflux and function as well as gastric emptying and acid secretion during treatment with short-acting (lixisenatide) and long-acting (liraglutide) GLP-1 RAs.

RESEARCH DESIGN AND METHODS

A total of 57 subjects with type 2 diabetes were randomized to a 10-week treatment with lixisenatide or liraglutide. Changes from baseline in the number of reflux episodes during 24-h pH registration in the lower esophagus, lower esophagus sphincter pressure, gastric emptying (¹³C-sodium octanoate acid breath test), and gastric acid secretion (¹³C-calcium carbonate breath test) were analyzed.

RESULTS

Gastric emptying half-time was delayed by 52 min (Δ 95% CI 16, 88) with lixisenatide (P = 0.0065) and by 25 min (3, 46) with liraglutide (P = 0.025). There was no difference in the number of reflux episodes (mean ± SEM 33.7 ± 4.1 vs. 40.1 ± 5.3 for lixisenatide and liraglutide, respectively, P = 0.17) or the extent of gastroesophageal reflux (DeMeester score) (35.1 ± 6.7 vs. 39.7 ± 7.5, P = 0.61), with similar results for the individual GLP-1 RAs. No significant changes from baseline in other parameters of esophageal motility and lower esophageal sphincter function were observed. Gastric acidity decreased significantly by -20.7% (-40.6, -0.8) (P = 0.042) with the GLP-1 RAs.

CONCLUSIONS

Lixisenatide exerted a more pronounced influence on gastric emptying after breakfast than liraglutide. Neither lixisenatide nor liraglutide had significant effects on esophageal reflux or motility. Gastric acid secretion appears to be slightly reduced by GLP-1 RAs.

Acute Effects of Lixisenatide on Energy Intake in Healthy Subjects and Patients with Type 2 Diabetes: Relationship to Gastric Emptying and Intragastric Distribution

Glucagon-like peptide-1 receptor agonists induce weight loss, which has been suggested to relate to the slowing of gastric emptying (GE). In health, energy intake (EI) is more strongly related to the content of the distal, than the total, stomach. We evaluated the effects of lixisenatide on GE, intragastric distribution, and subsequent EI in 15 healthy participants and 15 patients with type 2 diabetes (T2D). Participants ingested a 75-g glucose drink on two separate occasions, 30 min after lixisenatide (10 mcg) or placebo subcutaneously, in a randomised, double-blind, crossover design. GE and intragastric distribution were measured for 180 min followed by a buffet-style meal, where EI was quantified. Relationships of EI with total, proximal, and distal stomach content were assessed. In both groups, lixisenatide slowed GE markedly, with increased retention in both the proximal (p < 0.001) and distal (p < 0.001) stomach and decreased EI (p < 0.001). EI was not related to the content of the total or proximal stomach but inversely related to the distal stomach at 180 min in health on placebo (r = -0.58, p = 0.03) but not in T2D nor after lixisenatide in either group. In healthy and T2D participants, the reduction in EI by lixisenatide is unrelated to changes in GE/intragastric distribution, consistent with a centrally mediated effect.