Normal and disordered gastric emptying in diabetes: recent insights into (patho)physiology, management and impact on glycaemic control

Amylin: From Mode of Action to Future Clinical Potential in Diabetes and Obesity

Precision diabetology is increasingly becoming diabetes phenotype-driven, whereby the specific hormonal imbalances involved are taken into consideration. Concomitantly, body weight-favorable therapeutic approaches are being dictated by the obesity pandemic, which extends to all diabetes subpopulations. Amylin, an anorexic neuroendocrine hormone co-secreted with insulin, is deficient in individuals with diabetes and plays an important role in postprandial glucose homeostasis, with additional potential cardiovascular and neuroprotective functions. Its actions include suppressing glucagon secretion, delaying gastric emptying, increasing energy expenditure and promoting satiety. While amylin holds promise as a therapeutic agent, its translation into clinical practice is hampered by complex receptor biology, the limitations of animal models, its amyloidogenic properties and pharmacokinetic challenges. In individuals with advanced β-cell dysfunction, supplementing insulin therapy with pramlintide, the first and currently only approved injectable short-acting selective analog of amylin, has demonstrated efficacy in enhancing both postprandial and overall glycemic control in both type 2 diabetes (T2D) and type 1 diabetes (T1D) without increasing the risk of hypoglycemia or weight gain. Current research focuses on several key strategies, from enhancing amylin stability by attaching polyethylene glycol or carbohydrate molecules to amylin, to developing oral amylin formulations to improve patients' convenience, as well as developing various combination therapies to enhance weight loss and glucose regulation by targeting multiple receptors in metabolic pathways. The novel synergistically acting glucagon-like peptide-1 (GLP-1) receptor agonist combined with the amylin agonist, CagriSema, shows promising results in both glucose regulation and weight management. As such, amylin agonists (combined with other members of the incretin class) could represent the elusive drug candidate to address the multi-hormonal dysregulations of diabetes subtypes and qualify as a precision medicine approach that surpasses the long overdue division into T1DM and T2DM. Further development of amylin-based therapies or delivery systems is crucial to fully unlock the therapeutic potential of this intriguing hormone.Graphical abstract available for this article.

Aspiration risk and strategic approach for patients receiving GLP-1 receptor agonists undergoing elective surgery

Perioperative management of patients receiving a glucagon-like peptide-1 receptor agonist (GLP-1 RA) remains challenging for the anesthesiologist. Despite the approval of GLP-1 RAs 2 decades ago, the recent reports of aspiration and postoperative pulmonary complications drew attention to this group of medications and resulted in multiple societal guidelines that would provide recommendations for anesthesiologists and proceduralists on the appropriate perioperative management of GLP-1 RAs. However, despite these guidelines and proposed options, there was a lack of adequate evidence to support holding versus continuing the medication, as well as data related to the role of gastric ultrasound in that decision-making process. The release of multiple societal guidelines and studies evaluating the impact of GLP-1 RAs on perioperative outcomes resulted in more controversy and uncertainty for the clinician anesthesiologist to follow. The ultimate goal for perioperative management of these medications is to evaluate an individual patient's risk of aspiration, rather than assuming the risk is low when holding the medication appropriately or high if not holding it. Furthermore, it is unclear whether holding these types of medicines or unnecessary postponing of surgery may result in adverse outcomes. In this narrative review, we present a summary of the existing literature on the topic with a focus on the risk of aspiration and a recommendation for perioperative management to include the utilization of gastric ultrasound for surgery patients based on their risks.

A case series of incidents reported to webAIRS relating to glucagon-like peptide 1 agonist use

The increasing prescription of glucagon-like peptide 1 (GLP-1) agonists presents a peri-operative challenge for anaesthetists. These drugs delay gastric emptying, potentially increasing pulmonary aspiration risk. Despite recent recommendations from the Australian and New Zealand College of Anaesthetists, Australian Society of Anaesthetists, and American Society of Anesthesiologists, there remain no formalised guidelines regarding preoperative optimisation for patients taking GLP-1 agonists. Given the current lack of evidence, we present a case series of incidents involving patients treated with GLP-1 agonists reported to webAIRS, a web-based anaesthetic incident reporting system in Australia and New Zealand. Among 11,700 reports from July 2009 to April 2024, 13 incidents related to GLP-1 agonist use were identified, including seven cases concerning aspiration. Patient factors potentially contributing to increased aspiration risks in these incidents included a higher body mass index, type 2 diabetes mellitus, gastro-oesophageal reflux disease, emergency case, and time from GLP-1 agonist cessation. Most incidents involved a rapid sequence induction for general anaesthesia with no cases utilising gastric ultrasound, preoperative nasogastric tube insertion, or intravenous erythromycin use. This case series highlights the potential concerns relating to GLP-1 treatment in the perioperative setting. Interdisciplinary collaboration and communication between anaesthetists, surgeons, general practitioners and endocrinologists are required to further investigate and establish preoperative guidelines for safe GLP-1 agonist use. Specifically, consideration in determining actual gastric contents of each patient despite generic fasting guidelines is needed. Early preoperative risk stratification should also improve patient safety and outcomes.

Glucagon-like peptide-1 receptor agonists increase the risk of residual gastric content and pulmonary aspiration on upper endoscopy: A meta-analysis

BACKGROUND AND AIMS

Glucagon-like peptide-1 receptor agonists (GLP1-RA) are associated with increased residual gastric content (RGC); however, there is debate about their impact on RGC-related clinical outcomes, particularly aspiration.

METHODS

PubMed, Embase, Web of Science and Cochrane Library databases were systematically searched for studies published up to January 4, 2025, comparing GLP1-RA with control groups (non-GLP1-RA) in patients undergoing endoscopy. The outcomes of interest included the risk of RGC, pulmonary aspiration, interrupted and repeated endoscopic procedures, and delays in gastric transit time during capsule endoscopy. For the meta-analysis, a random-effects model was used to calculate the pooled odds ratio (OR) and mean difference (MD) with 95 % confidence intervals (CIs).

RESULTS

Thirty-nine studies composed of a total of 1,253,498 subjects, were included. The pooled analysis demonstrated that the GLP1-RA group had a significantly increased risk of RGC (OR 4.86, 95 % CI 3.85-6.14; adjusted OR 5.24, 95 % CI 3.49-7.87), pulmonary aspiration (OR 2.29, 95 % CI 1.36-3.87), interrupted endoscopic procedures (OR 3.22, 95 % CI 1.65-6.29), repeated endoscopy (OR 2.16, 95 % CI 1.14-4.11), and delays in gastric transit time during capsule endoscopy (MD 45.51, 95 % CI 1.33-89.68).

CONCLUSIONS

GLP1-RA use increased the risk of RGC, pulmonary aspiration, interrupted and repeated endoscopy and gastric transit time, reducing the safety and completion of upper endoscopy.

Postoperative Aspiration Pneumonia Among Adults Using GLP-1 Receptor Agonists

Importance

Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) have been increasingly prescribed for weight management in recent years. However, little is known about whether preoperative GLP-1 RA use is associated with a greater risk of complications after surgery.

Objective

To investigate whether preoperative GLP-1 RA use is associated with postoperative aspiration pneumonia among patients undergoing common surgical procedures.

Design, Setting, and Participants

This retrospective cohort study, conducted using MarketScan commercial claims databases, included patients who underwent 1 of 14 common surgical procedures from April 1, 2020, to September 30, 2022. Individuals who were younger than 18 years, underwent multiple surgical procedures, or had a preoperative history of pneumonia or acute respiratory failure in the 90 days preceding surgery were excluded. Data were analyzed from December 2023 to March 2024.

Main Outcome and Measures

The primary outcome was aspiration pneumonia in the 30-day postoperative period. Multivariable logistic regressions were performed, adjusting for patient and surgical characteristics.

Results

This study included 366 476 patients (median age, 53 years [IQR, 43-62 years]), of whom 56.4% were women. In the cohort, 5931 patients (1.6%) had a preoperative prescription for a GLP-1 RA. Patients using GLP-1 RAs were more likely to be female (3502 [59.0%] vs 203 288 [56.4%]) and diagnosed with both obesity and diabetes (2819 [47.5%] vs 24 635 [6.8%]) compared with nonusers. Adjusted analysis showed no significant differences in the odds of postoperative pneumonia (odds ratio, 0.78; 95% CI, 0.57-1.06; P = .12) between GLP-1 RA users and nonusers.

Conclusions and Relevance

This cohort study found no significant association between the preoperative use of GLP-1 RAs and short-term postoperative aspiration pneumonia despite growing concerns about the adverse effects of these medications after surgery. This finding suggests that it may be beneficial to reassess the preoperative withholding guidelines for GLP-1 RAs.

Performance of the 1 h oral glucose tolerance test in predicting type 2 diabetes and association with impaired β-cell function in Asians: a national prospective cohort study

Background

Postprandial glucose concentration 1-h (1 h-PG) after an oral glucose tolerance test (OGTT) has similar or superior performance to 2 h-PG in predicting type-2 diabetes mellitus (T2DM) in several populations, and is simpler to obtain in clinical practice. However, studies in Asians are scarce. We investigated the utility of elevated baseline 1 h-PG in predicting T2DM incidence within three years, and its relationship with β-cell function in 1250 non-diabetic Asian participants.

Methods

Participants underwent an OGTT, an intravenous glucose challenge and a hyperinsulinemic-euglycemic clamp to determine glucose tolerance, acute insulin response (AIR) and insulin sensitivity at baseline. OGTTs were repeated every six months until study completion to monitor T2DM conversion.

Findings

The area under the receiver operating characteristic curve of 1 h-PG was not significantly different from 2 h-PG (AUC1h-PG = 0.883 vs. AUC2h-PG = 0.907; ΔAUC = -0.024, P = 0.124) and the optimal 1 h-PG cut-off was ≥10.7 mmol/L. When groups of high/low 1 h-PG and 2 h-PG at baseline were compared, AIR and disposition index were significantly lower in groups with high 1 h-PG, and both had a stronger correlation with 1 h-PG, indicating that impaired β-cell function was more strongly associated with elevated 1 h-PG than 2 h-PG.

Interpretation

The ability of 1 h-PG to detect Asians at risk of developing T2DM within three years is on par with 2 h-PG and the optimal cut-off is 10.7 mmol/L. Elevated 1 h-PG is associated with β-cell dysfunction. We conclude that 1 h-PG can be considered as a primary OGTT time point to identify Asians at risk for T2DM, allowing for screening at a reduced time and cost, and with lower patient burden.

Funding

National Medical Research Council (NMRC), Ministry of Health (MOH; Singapore) Industry Alignment Fund [NMRC/MOHIAFCat1/0048/2016] and Janssen Pharmaceuticals Inc. (USA).

Clinical Consequences of Delayed Gastric Emptying With GLP-1 Receptor Agonists and Tirzepatide

CONTEXT

Glucagon-like peptide-1 (GLP-1) receptor agonists (RAs) are established therapeutics for type 2 diabetes and obesity. Among other mechanisms, they slow gastric emptying and motility of the small intestine. This helps to limit postprandial glycemic excursions and reduce chylomicron formation and triglyceride absorption. Conversely, motility effects may have detrimental consequences, eg, retained gastric contents at endoscopy or general anesthesia, potentially complicated by pulmonary aspiration or bowel obstruction.

DATA ACQUISITION

We searched the PubMed database for studies involving GLP-1RA therapy and adverse gastrointestinal/biliary events.

DATA SYNTHESIS

Retained gastric contents at the time of upper gastrointestinal endoscopy are found more frequently with GLP-1 RAs but rarely are associated with pulmonary aspiration. Well-justified recommendations for the periprocedural management of GLP-1RAs (eg, whether to withhold these medications and for how long) are compromised by limited evidence. Important aspects to be considered are (1) their long half-lives, (2) the capacity of GLP-1 receptor agonism to slow gastric emptying even at physiological GLP-1 concentrations, (c) tachyphylaxis observed with prolonged treatment, and (d) the limited effect on gastric emptying in individuals with slow gastric emptying before initiating treatment. Little information is available on the influence of diabetes mellitus itself (ie, in the absence of GLP-1 RA treatment) on retained gastric contents and pulmonary aspiration.

CONCLUSION

Prolonged fasting periods regarding solid meal components, point-of-care ultrasound examination for retained gastric content, and the use of prokinetic medications like erythromycin may prove helpful and represent an important area needing further study to increase patient safety for those treated with GLP-1 RAs.

Inuit population have shorter gastric emptying, higher duodenal motility and altered pan-enteric micromilieu: a comparative study between Greenlandic and Danish populations with and without type 2 diabetes

Gastrointestinal function plays a pivotal role in nutrient absorption and overall digestive health. Abnormal gastric emptying is closely linked to type 2 diabetes, impacting blood glucose regulation and causing gastrointestinal symptoms. This study aims to investigate and compare segmental transit times, motility indices, and micromilieu between Greenlandic Inuit and Danish individuals with and without type 2 diabetes. We included forty-four Greenlandic Inuit, twenty-three of whom had type 2 diabetes, and age and gender-matched Danish individuals. Segmental transit time, motility, and luminal environment were measured using the SmartPill®. Greenlandic controls displayed shorter gastric emptying time (GET) (163 min), higher gastric median pH (2.0 pH) and duodenal median contractions (18.2 mm Hg) compared to Greenlanders with type 2 diabetes (GET: 235 min, pH:1.9, median duodenal contraction 18.4 mm Hg) and Danish controls (GET: 190, pH:1.2 median duodenal contraction 17.5 mmHg). Despite similar anti-diabetic management efforts, variations in gastrointestinal physiology were evident, highlighting the complexity of diabetes and its interaction with ethnicity, suggesting potential dietary or even genetic influences, emphasising the necessity for personalised diabetes management approaches. Finally, the study opens possibilities for future research, encouraging investigations into the underlying mechanisms linking genetics, diet, and gastric physiology, as an understanding of factors can lead to more effective, tailored strategies for diabetes care and improved digestive health in diverse populations.

Physiology and Pharmacology of Effects of GLP-1-based Therapies on Gastric, Biliary and Intestinal Motility

Glucagon-like peptide-1 (GLP-1) receptor agonists and the dual GLP-1- and glucose-dependent insulinotropic polypeptide receptor co-agonist tirzepatide (referred to here collectively as "GLP-1-based therapy") are incretin-based therapies being used increasingly in the management of both type 2 diabetes and obesity. They are now recognized to have beneficial effects beyond improved glycemic control and weight loss, including cardiovascular and renal protection. GLP-1-based therapy also slows gastric emptying, which has benefits (lowering postprandial glucose), but also potential risks (eg, hypoglycemia in individuals on insulin or sulphonylurea therapy). Their effects on the gallbladder may also be beneficial, contributing to reducing postprandial triglycerides, but they also potentially increase the risk of biliary disease. In this review, we summarize the effects of GLP-1 and incretin-based therapeutics on gastric, biliary and small intestinal function. An improved understanding of these effects will optimize the use of these drugs.

A bibliometric analysis of diabetic gastroparesis from 1979 to 2024

Objective

Gastroparesis is one of the complications of diabetes mellitus, which has a major impact on the quality of life of patients, and the limited therapeutic options currently available make it a public health problem. No bibliometric studies on diabetic gastroparesis have been published to date. Therefore, the aim of this paper is to summarize and analyze the research hotspots for researchers.

Methods

Research articles related to Diabetic gastroparesis were searched in Web of Science Core Collection (WOSCC), and relevant information was extracted after screening. A comprehensive bibliometric analysis of 699 publications was conducted using Microsoft Excel 2019, Citespace and VOSviewers.

Result

A total of 699 papers from 738 institutions in 41 countries were retrieved. Publications in this field have increased rapidly since 1979. USA (n = 370) and Mayo Clinical (n = 69) were the most productive country and institution, respectively. Neurogastroenterology and Motility (n = 67) was the most published journal with Parkman, Henry P. (n = 40) having the highest number of articles; Gastroenterology and Mccallum, Richard W. were the most influential journals and authors.

Conclusions

The research hotspots of Diabetic gastroparesis are mainly focused on treatment modalities and pathological mechanisms. Future research in diabetic gastroparesis will focus on exploring the pathomechanisms, finding long-term effective treatments, and improving patients' quality of life.

Bariatric arterial embolization slows gastric emptying and improves postprandial glycaemia in obese dogs with impaired glucose tolerance

AIM

To evaluate the effects of bariatric arterial embolization (BAE) on gastric emptying of, and the glycaemic response to, an oral glucose load in an obese canine model with impaired glucose tolerance.

METHODS

Eleven male dogs were fed a high-fat, high-fructose diet for 7 weeks before receiving BAE, which involved selective embolization of the left gastric artery (n = 5; 14.9 ± 0.8 kg), or the sham (n = 6; 12.6 ± 0.8 kg) procedure. Postprocedural body weight was measured weekly for 4 weeks. Prior to and at 4 weeks postprocedure, a glucose solution containing 13C-acetate was administered orally for evaluation of the gastric half-emptying time (T50) and the glycaemic response. The relationship between the changes in the blood glucose area under the curve over the first 60 minutes (AUC0-60min) and the T50 was also assessed.

RESULTS

At 4 weeks postprocedure, BAE reduced body weight (BAE vs. the sham procedure: -5.7% ± 0.9% vs. 3.5% ± 0.9%, P < .001), slowed gastric emptying (T50 at baseline vs. postprocedure: 75.5 ± 2.0 vs. 82.5 ± 1.8 minutes, P = .021 in the BAE group; 73.8 ± 1.8 vs. 74.3 ± 1.9 minutes in the sham group) and lowered the glycaemic response to oral glucose (AUC0-60min at baseline vs. postprocedure: 99.2 ± 13.7 vs. 67.6 ± 9.8 mmol·min/L, P = .043 in the BAE group; 100.2 ± 13.4 vs. 103.9 ± 14.6 mmol·min/L in the sham group). The change in the glucose AUC0-60min correlated inversely with that of the T50 (r = -0.711; P = .014).

CONCLUSIONS

In a canine model with impaired glucose tolerance, BAE, while reducing body weight, slowed gastric emptying and attenuated the glycaemic response to an oral glucose load.

Gastrointestinal effects of GLP-1 receptor agonists: mechanisms, management, and future directions

The availability of glucagon-like peptide-1 (GLP-1) receptor agonists (RAs) such as liraglutide and semaglutide, and a GLP-1 and glucose dependent insulinotropic polypeptide coagonist (tirzepatide) represents a paradigm shift in the management of both type 2 diabetes and obesity. There is now considerable attention, including in the public media, on the effect of both long-acting and short-acting GLP-1RAs to delay gastric emptying. Although slowed gastric emptying is integral to reducing post-prandial blood glucose responses in type 2 diabetes, marked slowing of gastric emptying might also increase the propensity for longer intragastric retention of food, with a consequent increased risk of aspiration at the time of surgery or upper gastrointestinal endoscopy. This Personal View summarises current knowledge of the effects of GLP-1 and GLP-1RAs on gastrointestinal physiology, particularly gastric emptying, and discusses the implications for the development of sound pre-operative or pre-procedural guidelines. The development of pre-procedural guidelines is currently compromised by the poor evidence base, particularly in relation to the effect of long-acting GLP-1RAs on gastric emptying. We suggest pre-procedural management pathways for individuals on GLP-1RA-based therapy and discuss priorities for future research.

Medication reconciliation enhances the accuracy of gastric emptying scintigraphy

BACKGROUND

Gastroparesis (GP) is a prevalent sensorimotor disorder characterized by delayed gastric emptying without mechanical obstruction, posing significant diagnostic challenges. Gastric emptying scintigraphy (GES) is the gold standard for diagnosing GP. However, its accuracy can be compromised by many medications that affect gastric motility. This study evaluates the impact of medication reconciliation on the diagnostic accuracy of GES.

RESULTS

A significant proportion of patients (75%) were on medications known to affect gastric motility. Recommendations for medication adjustments were communicated, with 30% non-adherence. Adjustments in GES interpretations were necessary for 20% of patients following comprehensive medication reviews. The involvement of radiopharmacists facilitated accurate diagnostic conclusions, underscoring the critical role of medication reconciliation in GES accuracy.

CONCLUSION

Medication reconciliation enhanced the accuracy of GES in diagnosing gastroparesis, emphasizing the need to integrate clinical pharmacy practices into nuclear medicine. This interdisciplinary approach not only improves diagnostic accuracy but also enhances patient safety, advocating for the adoption of such practices in the management of gastroparesis.

The Gastric Connection: Serum Gastric Biomarkers, Metabolic Syndrome and Transition in Metabolic Status

Objective

Inflammation plays a crucial role in the development of metabolic syndrome (MetS). However, the roles of pepsinogens (PGs) and gastrin, known biomarkers linked to gastric inflammation, in MetS and the transition of MetS status are unclear. This research aimed to explore the relationship between MetS, the transition of MetS status, and levels of gastric biomarkers.

Methods

This large-scale cross-sectional study included 19162 participants aged 18-80 years between August 2021 and March 2024. Serum levels of the gastric biomarkers PGI, PGII, and gastrin-17 were analyzed using enzyme-linked immunosorbent assay. In addition, the relationship between transitions of MetS status based on 1032 MetS-negative participants from baseline to the second health exam after 2 years was considered. The association between MetS and the transitions of MetS status and gastric biomarkers was analyzed using logistic regression models.

Results

The prevalence of MetS in the study population was 31.4%, with higher rates in males (35.2%) than females (24.6%). Gastrin-17 levels were markedly elevated in participants with MetS, a trend observed in both genders. In the logistic regression analysis, after adjusting for confounding factors, gastrin-17 levels were strongly and positively correlated with MetS in the entire cohort and in males but not in females. Male participants with MetS had lower levels of PGI and PGII than those without MetS, whereas the opposite trend was observed in females. Logistic regression analysis indicated that PGI and PGII were not independently associated with MetS. During the follow-up of 2 years, 199 (19.28%) of the 1032 MetS-negative participants transitioned to MetS-positive status. As compared to the stable MetS-negative subjects, transition from MetS-negative to MetS-positive was associated with higher levels of gastrin-17, especially in males, but not in females.

Conclusion

Gastrin-17 is a promising biomarker for MetS, exhibiting potential utility in monitoring the transition of MetS status and revealing gender difference.

Randomised comparison of intravenous and subcutaneous routes of glucagon-like peptide-1 administration for lowering plasma glucose in hyperglycaemic subjects with type 2 diabetes

AIM

To perform a direct, double-blind, randomised, crossover comparison of subcutaneous and intravenous glucagon-like peptide-1 (GLP-1) in hyperglycaemic subjects with type 2 diabetes naïve to GLP-1-based therapy.

MATERIALS AND METHODS

Ten fasted, hyperglycaemic subjects (1 female, age 63 ± 10 years [mean ± SD], glycated haemoglobin 73.5 ± 22.0 mmol/mol [8.9% ± 2.0%], both mean ± SD) received subcutaneous GLP-1 and intravenous saline, or intravenous GLP-1 and subcutaneous saline. Infusion rates were doubled every 120 min (1.2, 2.4, 4.8 and 9.6 pmol·kg-1·min-1 for subcutaneous, and 0.3, 0.6, 1.2 and 2.4 pmol·kg-1·min-1 for intravenous). Plasma glucose, total and intact GLP-1, insulin, C-peptide, glucagon and gastrointestinal symptoms were evaluated over 8 h. The results are presented as mean ± SEM.

RESULTS

Plasma glucose decreased more with intravenous (by ~8.0 mmol/L [144 mg/dL]) than subcutaneous GLP-1 (by ~5.6 mmol/L [100 mg/dL]; p < 0.001). Plasma GLP-1 increased dose-dependently, but more with intravenous than subcutaneous for both total (∆max 154.2 ± 3.9 pmol/L vs. 85.1 ± 3.8 pmol/L; p < 0.001), and intact GLP-1 (∆max 44.2 ± 2.2 pmol/L vs. 12.8 ± 2.2 pmol/L; p < 0.001). Total and intact GLP-1 clearance was higher for subcutaneous than intravenous GLP-1 (p < 0.001 and p = 0.002, respectively). The increase in insulin secretion was greater, and glucagon was suppressed more with intravenous GLP-1 (p < 0.05 each). Gastrointestinal symptoms did not differ (p > 0.05 each).

CONCLUSIONS

Subcutaneous GLP-1 administration is much less efficient than intravenous GLP-1 in lowering fasting plasma glucose, with less stimulation of insulin and suppression of glucagon, and much less bioavailability, even at fourfold higher infusion rates.

Manipulation of Post-Prandial Hyperglycaemia in Type 2 Diabetes: An Update for Practitioners

This review paper explores post-prandial glycemia in type 2 diabetes. Post-prandial glycemia is defined as the period of blood glucose excursion from immediately after the ingestion of food or drink to 4 to 6 hours after the end of the meal. Post-prandial hyperglycemia is an independent risk factor for cardiovascular disease with glucose "excursions" being more strongly associated with markers of oxidative stress than the fasting or pre-prandial glucose level. High blood glucose is a major promoter of enhanced free radical production and is associated with the onset and progression of type 2 diabetes. Oxidative stress impairs insulin action creating a vicious cycle where repeated post-prandial glucose spikes are key drivers in the pathogenesis of the vascular complications of type 2 diabetes, both microvascular and macrovascular. Some authors suggest post-prandial hyperglycemia is the major cause of death in type 2 diabetes. Proper management of post-prandial hyperglycemia could yield up to a 35% cut in overall cardiovascular events, and a 64% cut in myocardial infarction. The benefits of managing post-prandial hyperglycemia are similar in magnitude to those seen in type 2 diabetes patients receiving secondary prevention with statins - prevention which today is regarded as fundamental by all practitioners. Given all the evidence surrounding the impact of post-prandial glycemia on overall outcome, it is imperative that any considered strategy for the management of type 2 diabetes should include optimum dietary, pharma, and lifestyle interventions that address glucose excursion. Achieving a low post-prandial glucose response is key to prevention and progression of type 2 diabetes and cardiometabolic diseases. Further, such therapeutic interventions should be sustainable and must benefit patients in the short and long term with the minimum of intrusion and side effects. This paper reviews the current literature around dietary manipulation of post-prandial hyperglycemia, including novel approaches. A great deal of further work is required to optimize and standardize the dietary management of post-prandial glycemia in type 2 diabetes, including consideration of novel approaches that show great promise.

Gastric emptying is slower in women than men with type 2 diabetes and impacts on postprandial glycaemia

AIM

To evaluate sex differences in gastric emptying and the glycaemic response to a glucose drink and a high carbohydrate meal in type 2 diabetes (T2D).

METHODS

In cohort 1, 70 newly diagnosed, treatment-naïve Chinese patients with T2D (44 men) recruited from a diabetes outpatient clinic ingested a 75-g glucose drink containing 150 mg 13C-acetate. In cohort 2, 101 Australian patients with T2D (67 male) recruited from the community, managed by diet and/or metformin monotherapy, ingested a semi-solid mashed potato meal, labelled with 100 μl 13C-octanoic acid. Breath samples were collected over 3 and 4 h, respectively, for assessment of gastric emptying, and venous blood was sampled for evaluation of glycaemia (with and without adjustment for each participant's estimated total blood volume).

RESULTS

Gastric emptying was slower in female than male subjects in both cohorts (both p < .01). Multiple linear regression analyses revealed that gastric emptying was independently associated with sex (both p < .05). Without adjustment for blood volume, the glycaemic responses to oral glucose and the mixed meal were greater in female subjects (both p < .001). However, after adjustment for blood volume, the glycaemic responses were greater in men (both p < .05).

CONCLUSIONS

Gastric emptying is slower in women than men with T2D, associated with a reduced blood volume-adjusted glycaemic response to oral glucose and a mixed meal in women. These observations highlight the sex difference in postprandial glucose handling, which is relevant to the personalized management of postprandial glycaemia in T2D.

Effect of lixisenatide on liquid gastric emptying in type 2 diabetes - Implications for the use of GLP-1 receptor agonists before procedures

Gastric emptying of a glucose drink was measured in people with type 2 diabetes given lixisenatide (20 μg/day or placebo) for 8 weeks. Intragastric retention at 240 min (2 (0-11)% vs 48 (3-97)%; P < 0.0001) was much greater with lixisenatide than placebo. Accordingly, lixisenatide may delay liquid gastric emptying markedly.

Approach to Obesity Treatment in Primary Care: A Review

Importance

More than 40% of US adults have obesity, which increases the risks for multiple chronic diseases and premature mortality. Historically, nonsurgical interventions often have not led to sufficient weight loss and maintenance to improve health, but highly effective antiobesity medications (AOMs) have recently become available, and additional effective therapeutics are under development. Given that most medical care for adults with obesity is delivered in primary care settings, guidance for integrating weight-management approaches is needed.

Observations

Lifestyle interventions can lead to a mean weight loss of 2% to 9% of initial weight at 1 year and increase the likelihood of weight loss of 5% or more, but weight regain over time is common even with continued treatment. Adjunctive treatments, including AOMs and surgical approaches, can lead to larger, more sustained weight loss and improvements in numerous obesity-associated medical conditions. Highly effective AOMs, including nutrient-stimulated hormone-based therapies, induce mean weight loss of 15% or more. Barriers to intervention, including access to care, have a disproportionate influence on populations most affected by obesity and its consequences.

Conclusions and Relevance

Primary care clinicians play a vital role in the assessment, management, and support of patients with obesity. With careful clinical assessment and shared decision-making, a flexible treatment plan can be developed that reflects evidence of treatment efficacy, patient preference, and feasibility of implementation. Adjunctive therapies to lifestyle interventions, including more effective pharmacotherapeutics for obesity, offer hope to patients and the potential for considerable improvements in health and quality of life.

Quantified Metrics of Gastric Emptying Delay by Glucagon-Like Peptide-1 Agonists: A Systematic Review and Meta-Analysis With Insights for Periprocedural Management

INTRODUCTION

Divergent recommendations for periprocedural management of glucagon-like peptide-1 (GLP-1) receptor agonist (GLP-1 RA) medications rely on limited evidence. We performed a systematic review and meta-analysis to provide quantitative measures of gastric emptying relevant to mechanisms of weight loss and to periprocedural management of GLP-1 RA. We hypothesized that the magnitude of gastric emptying delay would be low and of limited clinical significance to procedural sedation risks.

METHODS

A protocolized search identified studies on GLP-1 RA that quantified gastric emptying measures. Pooled estimates using random effects were presented as a weighted mean difference with 95% confidence intervals (CIs). Univariate meta-regression was performed to assess the influence of GLP-1 RA type, short-acting vs long-acting mechanism of action, and duration of treatment on gastric emptying.

RESULTS

Fifteen studies met the inclusion criteria. Five studies (n = 247) utilized gastric emptying scintigraphy. Mean T 1/2 was 138.4 minutes (95% CI 74.5-202.3) for GLP-1 RA vs 95.0 minutes (95% CI 54.9-135.0) for placebo, with a pooled mean difference of 36.0 minutes (95% CI 17.0-55.0, P < 0.01, I2 = 79.4%). Ten studies (n = 411) utilized the acetaminophen absorption test, with no significant delay in gastric emptying measured by T max , area under the curve (AUC) 4hr , and AUC 5hr with GLP-1 RA ( P > 0.05). On meta-regression, the type of GLP-1 RA, mechanism of action, and treatment duration did not impact gastric emptying ( P > 0.05).

DISCUSSION

While a gastric emptying delay of ∼36 minutes is quantifiable on GLP-1 RA medications, it is of limited magnitude relative to standard periprocedural fasting periods. There were no substantial differences in gastric emptying on modalities reflective of liquid emptying (acetaminophen absorption test), particularly at time points relevant to periprocedural care.

Alterations in Adipose Tissue Distribution, Cell Morphology, and Function Mark Primary Insulin Hypersecretion in Youth With Obesity

Excessive insulin secretion independent of insulin resistance, defined as primary hypersecretion, is associated with obesity and an unfavorable metabolic phenotype. We examined the characteristics of adipose tissue of youth with primary insulin hypersecretion and the longitudinal metabolic alterations influenced by the complex adipo-insular interplay. In a multiethnic cohort of adolescents with obesity but without diabetes, primary insulin hypersecretors had enhanced model-derived β-cell glucose sensitivity and rate sensitivity but worse glucose tolerance, despite similar demographics, adiposity, and insulin resistance measured by both oral glucose tolerance test and euglycemic-hyperinsulinemic clamp. Hypersecretors had greater intrahepatic and visceral fat depots at abdominal MRI, hypertrophic abdominal subcutaneous adipocytes, higher free fatty acid and leptin serum levels per fat mass, and faster in vivo lipid turnover assessed by a long-term 2H2O labeling protocol. At 2-year follow-up, hypersecretors had greater fat accrual and a threefold higher risk for abnormal glucose tolerance, while individuals with hypertrophic adipocytes or higher leptin levels showed enhanced β-cell glucose sensitivity. Primary insulin hypersecretion is associated with marked alterations in adipose tissue distribution, cellularity, and lipid dynamics, independent of whole-body adiposity and insulin resistance. Pathogenetic insight into the metabolic crosstalk between β-cell and adipocyte may help to identify individuals at risk for chronic hyperinsulinemia, body weight gain, and glucose intolerance.

ARTICLE HIGHLIGHTS

Drug-Drug Interactions Between Glucagon-Like Peptide 1 Receptor Agonists and Oral Medications: A Systematic Review

BACKGROUND

Glucagon-like peptide 1 receptor agonists (GLP1RAs) are used in the treatment of diabetes and obesity. Their slowing effect of gastric emptying might change oral drug absorption, potentially affecting pharmacokinetics, particularly in the case of medications with a narrow therapeutic index.

PURPOSE

The purpose of this systematic review is to summarize data on drug-drug interactions between GLP1RAs and oral drugs.

DATA SOURCES

The PubMed and EMBASE databases were searched up to November, 1st 2023.

STUDY SELECTION

We selected pharmacokinetic studies of any injectable GLP1RA given with an oral medication, and product prescribing sheets reporting data without access to the original study.

DATA EXTRACTION

Two authors independently extracted the data.

DATA SYNTHESIS

Twenty-two reports and six prescribing sheets were included. Treatment with GLP1RAs resulted in unaffected or reduced Cmax and delayed tmax of drugs with high solubility and permeability (warfarin, contraceptive pills, acetaminophen), drugs with high solubility and low permeability (angiotensin converting enzyme inhibitors), drugs with low solubility and high permeability (statins) and drugs with low solubility and permeability (digoxin). However, the use of GLP1RAs did not exert clinically significant changes in the AUC or differences in clinically relevant endpoints.

LIMITATIONS

The major limitations of the studies that are included in this systematic review are the enrollment of healthy subjects and insufficient data in conditions that might affect pharmacokinetics (e.g., kidney dysfunction).

CONCLUSIONS

To conclude, reduced Cmax and delayed tmax of drugs co-administered with GLP1RAs are consistent with the known delayed gastric output by the latter. Nevertheless, the overall drug exposure was not considered clinically significant. Dose adjustments are probably not required for simultaneous use of GLP1RAs with oral medications. Still, results should be carefully generalized to cases of background kidney dysfunction or when using drugs with narrow therapeutic index. The study is registered in PROSPERO: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022332339 .

Gastric emptying of a glucose drink is predictive of the glycaemic response to oral glucose and mixed meals, but unrelated to antecedent glycaemic control, in type 2 diabetes

BACKGROUND

Gastric emptying (GE), with wide inter-individual but lesser intra-individual variations, is a major determinant of postprandial glycaemia in health and type 2 diabetes (T2D). However, it is uncertain whether GE of a carbohydrate-containing liquid meal is predictive of the glycaemic response to physiological meals, and whether antecedent hyperglycaemia influences GE in T2D. We evaluated the relationships of (i) the glycaemic response to both a glucose drink and mixed meals with GE of a 75 g glucose drink, and (ii) GE of a glucose drink with antecedent glycaemic control, in T2D.

METHODS

Fifty-five treatment-naive Chinese adults with newly diagnosed T2D consumed standardised meals at breakfast, lunch and dinner with continuous interstitial glucose monitoring. On the subsequent day, a 75 g glucose drink containing 150 mg 13C-acetate was ingested to assess GE (breath test) and plasma glucose response. Serum fructosamine and HbA1c were also measured.

RESULTS

Plasma glucose incremental area under the curve (iAUC) within 2 hours after oral glucose was related inversely to the gastric half-emptying time (T50) (r = -0.34, P = 0.012). The iAUCs for interstitial glucose within 2 hours after breakfast (r = -0.34, P = 0.012) and dinner (r = -0.28, P = 0.040) were also related inversely to the T50 of oral glucose. The latter, however, was unrelated to antecedent fasting plasma glucose, 24-hour mean interstitial glucose, serum fructosamine, or HbA1c.

CONCLUSIONS

In newly diagnosed, treatment-naive, Chinese with T2D, GE of a 75 g glucose drink predicts the glycaemic response to both a glucose drink and mixed meals, but is not influenced by spontaneous short-, medium- or longer-term elevation in glycaemia.

Gastric emptying during and following resolution of moderate diabetic ketoacidosis in type 1 diabetes: a case series

INTRODUCTION

To use the 'gold standard' technique of scintigraphy to quantify gastric emptying (GE) as soon as practicable during an admission with diabetic ketoacidosis (DKA) and following its resolution at least 7 days later.

RESEARCH DESIGN AND METHODS

Five patients with type 1 diabetes, age 29±12 years; Body Mass Index 23±3 kg/m2; hemoglobin A1c 11.3%±1.9%, were studied during an admission with DKA and following its resolution. Solid and liquid GE were measured using scintigraphy. Solid emptying was assessed via the percentage intragastric retention at 100 min and that of liquid by the 50% emptying time.

RESULTS

There was no difference in either solid or liquid GE at the initial study compared with the follow-up. Median (IQR) solid retention was 47±20 versus 38%±33%, respectively; p=0.31, and time to empty 50% of liquid was 37±25 min versus 35±15 min, p=0.31, at the initial and follow-up GE study, respectively.

CONCLUSIONS

GE of solids and liquids is not affected by moderate DKA, inferring that earlier reintroduction of oral intake may be appropriate.

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.

Proposed treatment strategy for reactive hypoglycaemia

Background/aim

Managing reactive hypoglycaemia (RH) poses challenges due to limited and often ineffective treatment options. We report a case series and draw on this to propose a stepwise treatment approach consisting of lifestyle modifications, metformin, GLP-1 analogues, and the use of flash glucose monitoring technology.

Method

A retrospective review was conducted to analyse the management of 11 cases presenting with recurrent RH symptoms.

Result

Two patients experienced successful resolution of symptoms through lifestyle modifications. Metformin alone was effective in treating seven out of nine patients who received pharmacological treatment. Two patients with previous upper gastrointestinal surgery showed a partial response to metformin and benefited further from additional long-acting GLP-1 analogue. Pharmacological intervention led to significant reductions in insulin and C-peptide levels in repeat mixed meal tolerance tests (P-values 0.043 for insulin and 0.006 for C-peptide). Finally, flash glucose monitoring technology was useful in early detection and preventing episodes of hypoglycaemia in one of these patients with persistent symptoms.

Conclusion

These findings highlight the potential efficacy of escalated treatment strategies for RH, including the use of metformin, GLP-1 analogues, and flash glucose monitoring technology.

Rectal sensitivity correlated with gastrointestinal-mediated glucose disposal, but not the incretin effect

OBJECTIVE

The mechanisms behind the diminished incretin effect in type 2 diabetes are uncertain, but impaired vagal transmission has been suggested. We aimed to investigate the association between the incretin effect and autonomic neuropathy, and the degree of dysglycaemia and duration of diabetes.

DESIGN AND METHODS

For a cross-sectional study, we included participants with either longstanding type 2 diabetes, recent onset, untreated diabetes and controls without diabetes matched for age, sex and body mass index. Autonomic nerve function was assessed with cardiovascular reflex tests, heart rate variability and sudomotor function. Visceral afferent nerves in the gut were tested performing rapid rectal balloon distention. An oral glucose tolerance test and an intravenous isoglycaemic glucose infusion were performed to calculate the incretin effect and gastrointestinal-mediated glucose disposal (GIGD).

RESULTS

Sixty-five participants were recruited. Participants with diabetes had rectal hyposensitivity for earliest sensation (3.7 ± 1.1 kPa in longstanding, 4.0 ± 1.3 in early), compared to controls (3.0 ± 0.9 kPa), p = .005. Rectal hyposensitivity for earliest sensation was not associated with the incretin effect (rho = -0.204, p = .106), but an association was found with GIGD (rho -0.341, p = .005). Incretin effect and GIGD were correlated with all glucose values, HbA1c and duration of diabetes.

CONCLUSIONS

Rectal hyposensitivity was uncovered in both longstanding and early type 2 diabetes, and was not associated with the incretin effect, but with GIGD, implying a potential link between visceral neuropathy and gastrointestinal handling of glucose. Both the incretin effect and GIGD were associated with the degree of dysglycaemia and the duration of diabetes.

PREVIOUSLY PUBLISHED

Some of the data have previously been published and presented as a poster on the American Diabetes Association 83rd Scientific Sessions: Meling et al; 1658-P: Rectal Hyposensitivity, a Potential Marker of Enteric Autonomic Nerve Dysfunction, Is Significantly Associated with Gastrointestinally Mediated Glucose Disposal in Persons with Type 2 Diabetes. Diabetes 20 June 2023; 72 (Supplement_1): 1658-P. https://doi.org/10.2337/db23-1658-P.

Postprandial plasma GLP-1 levels are elevated in individuals with postprandial hypoglycaemia following Roux-en-Y gastric bypass - a systematic review

BACKGROUND AND AIMS

Bariatric surgery is the most effective treatment in individuals with obesity to achieve remission of type 2 diabetes. Post-bariatric surgery hypoglycaemia occurs frequently, and management remains suboptimal, because of a poor understanding of the underlying pathophysiology. The glucoregulatory hormone responses to nutrients in individuals with and without post-bariatric surgery hypoglycaemia have not been systematically examined.

MATERIALS AND METHODS

The study protocol was prospectively registered with PROSPERO. PubMed, EMBASE, Web of Science and the Cochrane databases were searched for publications between January 1990 and November 2021 using MeSH terms related to post-bariatric surgery hypoglycaemia. Studies were included if they evaluated individuals with post-bariatric surgery hypoglycaemia and included measurements of plasma glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), insulin, C-peptide and/or glucagon concentrations following an ingested nutrient load. Glycated haemoglobin (HbA1c) was also evaluated. A random-effects meta-analysis was performed, and Hedges' g (standardised mean difference) and 95% confidence intervals were reported for all outcomes where sufficient studies were available. The τ2 estimate and I2 statistic were used as tests for heterogeneity and a funnel plot with the Egger regression-based test was used to evaluate for publication bias.

RESULTS

From 377 identified publications, 12 were included in the analysis. In all 12 studies, the type of bariatric surgery was Roux-en-Y gastric bypass (RYGB). Comparing individuals with and without post-bariatric surgery hypoglycaemia following an ingested nutrient load, the standardised mean difference in peak GLP-1 was 0.57 (95% CI, 0.32, 0.82), peak GIP 0.05 (-0.26, 0.36), peak insulin 0.84 (0.44, 1.23), peak C-peptide 0.69 (0.28, 1.1) and peak glucagon 0.05 (-0.26, 0.36). HbA1c was less in individuals with hypoglycaemia - 0.40 (-0.67, -0.12). There was no evidence of substantial heterogeneity in any outcome except for peak insulin: τ2 = 0.2, I2 = 54.3. No publication bias was evident.

CONCLUSION

Following RYGB, postprandial peak plasma GLP-1, insulin and C-peptide concentrations are greater in individuals with post-bariatric surgery hypoglycaemia, while HbA1c is less. These observations support the concept that antagonism of GLP-1 would prove beneficial in the management of individuals with hypoglycaemia following RYGB.PROSPERO Registration Number: CRD42021287515.

Rapid gastric emptying during pregnancy in a rat model

BACKGROUND/AIMS

The effect of pregnancy on gastric emptying has not been established, although the predominant clinical assumption is that gastric emptying is delayed during pregnancy. We hypothesized that the rate of emptying of nutrients during pregnancy is not delayed, but is actually more rapid when compared to the non-pregnant state. The rate of gastric emptying is a major determinant of postprandial glucose elevations.

MATERIALS AND METHODS

24 female and 4 male Spague-Dawley rats were used. Female rats were randomly divided into two groups: eight rats for the control group and sixteen rats for the pregnant group. Using physiologic, non-traumatic nuclear medicine scintigraphy imaging methodology, the authors studied gastric emptying of a liquid mixed meal in pregnant rats and non-pregnant controls. Body weights, daily food ingestion, and the rate of nutrient gastric emptying were recorded in both groups at pre-pregnancy, early pregnancy, and late pregnancy.

RESULTS

The authors found that pregnancy in this rat model is associated with a 37-43% increased rate of nutrient gastric emptying from the stomach in late pregnancy as compared to non-pregnant control rats and pre-pregnancy rats.

CONCLUSION

These findings contradict the current clinical assumption that gastric emptying is delayed in pregnancy. If further studies confirm a more rapid gastric emptying rate during human pregnancy, new therapies aimed at slowing the rate of nutrient absorption should be considered for the prevention and treatment of pregnancy-associated nausea, gestational diabetes, and other insulin-resistant pregnancy-associated states such as pre-eclampsia.

The role of gastric emptying in glucose homeostasis and defense against hypoglycemia: Innocent bystander or partner in crime?

Maintenance of plasma glucose (PG) homeostasis is due to a complex network system. Even a minor fall in PG activates multiple neuroendocrine actions promoting hormonal, metabolic and behavioral responses, which prevent and ultimately recover hypoglycemia, primarily neuroglycopenia. Among these responses, gastric emptying (GE) plays an important role by coordinated mechanisms which regulate transit and absorption of nutrients through the small intestine. A bidirectional relationship between GE and glycemia has been established: GE may explain the up to 30-40 % variance in glycemic response following a carbohydrate-rich meal. In addition, acute and chronic hyperglycemia induce deceleration of GE after meals. Hypoglycemia accelerates GE, but its role in counterregulation has been poorly investigated. The role of GE as a counterregulatory mechanism has been confirmed in pathophysiological conditions, such as gastroparesis or following recurrent hypoglycemia. Therefore, it could represent an "ancestral" mechanism, highly conservative and effective in all individuals, conditions and clinical contexts. Recent guidelines recommend GLP-1 receptor agonists (GLP-1RAs) either as the first injectable therapy for type 2 diabetes mellitus or in combination with insulin. Considering the potential impact on GE, it would be important to study subjects on GLP-1 RAs during hypoglycemia, to establish whether a possible deceleration of GE impairs glucose counterregulation.

Underutilisation of gastric emptying studies and underrecognition of gastroparesis in people with diabetes treated in a hospital setting

Delayed gastric emptying occurs in up to 30% of patients with long-standing diabetes and causes significant morbidity. We performed a retrospective cohort study of 341 patients who had participated in a gastric emptying study from 2018 to 2021 in a large teaching hospital. Given the expected prevalence of gastroparesis in people with diabetes, there were fewer studies than anticipated, which could lead to gastroparesis underrecognition.

Prevalence of gastroparesis in diabetic patients: a systematic review and meta-analysis

Although there was no significant heterogeneity in the meta-publication, sensitivity analyses revealed significant heterogeneity. Overall, the prevalence was higher in women (N = 6, R = 4.6%, 95% CI 3.1%, 6.0%, and I2 = 99.8%) than in men (N = 6, R = 3.4%, 95% CI 2.0%, 4.7%, and I2 = 99.6the %); prevalence of type 2 diabetes (N = 9, R = 12.5%, 95% CI 7.7%, 17.3%, and I2 = 95.4%) was higher than type 1 diabetes (N = 7, R = 8.3%, 95% CI 6.4%, 10.2%, and I2 = 93.6%); the prevalence of DGP was slightly lower in DM patients aged over 60 years (N = 6, R = 5.5%, 95% CI 3.3%, 7.7%, and I2 = 99.9%) compared to patients under 60 years of age (N = 12, R = 15.8%, 95% CI 11 15.8%, 95% CI 11.4%, 20.2%, and I2 = 88.3%). In conclusion, our findings indicate that the combined estimated prevalence of gastroparesis in diabetic patients is 9.3%. However, the sensitivity of the results is high, the robustness is low, and there are significant bias factors. The subgroup analysis revealed that the prevalence of DM-DGP is associated with factors such as gender, diabetes staging, age, and study method.

Whey Protein Premeal Lowers Postprandial Glucose Concentrations in Adults Compared with Water-The Effect of Timing, Dose, and Metabolic Status: a Systematic Review and Meta-analysis

BACKGROUND

Serving whey protein before a meal in order to lower postprandial blood glucose concentrations is known as a premeal. The underlying mechanisms are only partly understood but may involve stimulation of glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), and insulin secretion together with a slower gastric emptying rate.

OBJECTIVES

The objective of this systematic review and meta-analysis was to review all randomized clinical trials investigating premeals with whey protein in comparison with a nonactive comparator (control) that evaluated plasma glucose, GLP-1, GIP, insulin, and/or gastric emptying rate. Secondary aims included subgroup analyses on the timing and dose of the premeal together with the metabolic state of the participants [lean, obese, and type 2 diabetes mellitus (T2DM)].

METHODS

We searched EMBASE, CENTRAL, PUBMED, and clinicaltrials.gov and found 16 randomized crossover trials with a total of 244 individuals. The last search was performed on 9 August, 2022.

RESULTS

Whey protein premeals lowered peak glucose concentration by -1.4 mmol/L [-1.9 mmol/L; -0.9 mmol/L], and the area under the curve for glucose was -0.9 standard deviation (SD) [-1.2 SD; -0.6 SD] compared with controls (high certainty). In association with these findings, whey protein premeals elevated GLP-1 (low certainty) and peak insulin (high certainty) concentrations and slowed gastric emptying rate (high certainty) compared with controls. Subgroup analyses showed a more pronounced and prolonged glucose-lowering effect in individuals with T2DM compared with participants without T2DM. The available evidence did not elucidate the role of GIP. The protein dose used varied between 4 and 55 g, and meta-regression analysis showed that the protein dose correlated with the glucose-lowering effects.

CONCLUSIONS

In conclusion, whey protein premeals lower postprandial blood glucose, reduce gastric emptying rate, and increase peak insulin. In addition, whey protein premeals may elevate plasma concentrations of GLP-1. Whey protein premeals may possess clinical potential, but the long-term effects await future clinical trials.

Striking a gut-liver balance for the antidiabetic effects of metformin

Metformin is the most prescribed drug for the treatment of type 2 diabetes mellitus (T2DM), but its mechanism of action has not yet been completely elucidated. Classically, the liver has been considered the major site of action of metformin. However, over the past few years, advances have unveiled the gut as an additional important target of metformin, which contributes to its glucose-lowering effect through new mechanisms of action. A better understanding of the mechanistic details of metformin action in the gut and the liver and its relevance in patients remains the challenge of present and future research and may impact drug development for the treatment of T2DM. Here, we offer a critical analysis of the current status of metformin-driven multiorgan glucose-lowering effects.

Retatrutide: a triple incretin receptor agonist for obesity management

INTRODUCTION

Obesity treatment is evolving rapidly with the emergence of agents targeting incretin receptors. Retatrutide, a triple agonist of these receptors, shows promise in obesity management.

AREAS COVERED

Retatrutide, in phase-2 trials, exhibited significant reductions in glycated hemoglobin (HbA1c) and dose-dependent weight loss in individuals with type 2 diabetes mellitus (T2DM). In non-T2DM individuals, it produced substantial weight loss and improved glucose levels, albeit with gastrointestinal side effects. The role of glucagon receptor agonism in the management of heart failure and its potential impact on eating patterns have also been covered in this article.

EXPERT OPINION

Although the reductions in HbA1c and dose-dependent weight loss among individuals with T2DM were significantly more for higher doses of retatrutide, it needs to be observed that the active comparator was dulaglutide, which is not approved for the treatment of obesity, at a dose of 1.5 mg, which is much lower than the highest approved dose of 4.5 mg. Dose-dependent increase in heart rate and incidents of mild to moderate cardiac arrythmias raise cardiovascular safety concerns and signify that carrying out long-term cardiovascular outcome trials (CVOTs) will be critical. In addition, retatrutide's potential in heart failure management is intriguing given the series of positive findings of semaglutide on cardiovascular outcomes.

Editorial: empirical pharmacological management of gastroparesis-a cautionary tale

This article is linked to Sanger and Andrews paper. To view this article, visit https://doi.org/10.1111/apt.17466.

Designer GLP1 poly-agonist peptides in the management of diabesity

INTRODUCTION

To date, the 21^st Century has witnessed key developments in the management of diabesity (a conflation of obesity and Type 2 Diabetes Mellitus [T2D]), including Glucagon Like Peptide 1 (GLP1) receptor agonist therapies, and recently the 'designer' GLP1 Poly-agonist Peptides (GLP1PPs).

AREAS COVERED

A PubMed search of published data on the GLP1PP class of therapies was conducted. The gut-brain axis forms complex multi-directional interlinks that include autonomic nervous signaling, components of the gut microbiota (including metabolic by-products and gram-negative cell wall components [e.g. endotoxinaemia]), and incretin hormones that are secreted from the gut in response to the ingestion of nutrients. The development of dual-incretin agonist therapies includes combinations of the GLP1 peptide with Glucose-dependent Insulinotropic Polypeptide (GIP), Glucagon (Gcg), Cholecystokinin (CCK), Peptide YY (PYY), and Glucagon-Like Peptide 2 (GLP2). Triple incretin agonist therapies are also under development.

EXPERT OPINION

At the dawn of a new era in the therapeutic management of diabesity, the designer GLP1PP class holds great promise, with each novel combination building on a preexisting palimpsest of clinical data and insights. Future innovations of the GLP1PP class will likely enable medically induced weight loss and glycemic control in diabesity to rival or even out-perform those resulting from bariatric surgery.

Review article: An analysis of the pharmacological rationale for selecting drugs to inhibit vomiting or increase gastric emptying during treatment of gastroparesis

BACKGROUND

Drugs which can inhibit nausea/vomiting and/or increase gastric emptying are used to treat gastroparesis, mostly 'off-label'. Within each category, they act at different targets and modulate different physiological mechanisms.

AIMS

Address the questions: In gastroparesis, why should blocking one pathway causing vomiting, be more appropriate than another? Why might increasing gastric emptying via one mechanism be more appropriate than another?

METHODS

Drugs used clinically were identified via consensus opinions and reviews, excluding the poorly characterised. Their pharmacology was defined, mapped to mechanisms influencing vomiting and gastric emptying, and rationale developed for therapeutic use.

RESULTS

Vomiting: Rationale for 5-HT₃ , D₂ , H₁ or muscarinic antagonists, and mirtazapine, amitriptyline, nortriptyline, are poor. Arguments for inhibiting central consequences of vagal afferent transmission by NK₁ antagonism are complicated by doubts over effects on nausea. Gastric emptying: Confusion emerges because of side-effects of drugs increasing gastric emptying: Metoclopramide (5-HT₄ agonist, D₂ and 5-HT₃ antagonist; also blocks some emetic stimuli and causes tardive dyskinesia) and Erythromycin (high-efficacy motilin agonist, requiring low doses to minimise side-effects). Limited trials with selective 5-HT₄ agonists indicate variable efficacy.

CONCLUSIONS

Several drug classes inhibiting vomiting have no scientific rationale. NK₁ antagonism has rationale but complicated by limited efficacy against nausea. Studies must resolve variable efficacy of selective 5-HT₄ agonists and apparent superiority over motilin agonists. Overall, lack of robust activity indicates a need for novel approaches targeting nausea (e.g., modulating gastric pacemaker or vagal activity, use of receptor agonists or new targets such as GDF15) and objective assessments of nausea.

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 iAUC0-30 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 iAUC0-30 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.

Impact of glucagon-like peptide 1 receptor agonist liraglutide and dipeptidyl peptidase-4 inhibitor sitagliptin on bowel cleaning and gastrointestinal symptoms in type 2 diabetes

Objective: Glucagon-like peptide 1 receptor agonists (GLP-1 RAs) and dipeptidyl peptidase-4 inhibitors (DPP-4i) profoundly affect the gastrointestinal motor system, which may increase the incidence of inadequate bowel cleaning and gastrointestinal symptoms. Hence, this observational study mainly aimed to assess the influence of GLP-1 RAs liraglutide and DPP-4i sitagliptin on bowel preparation in type 2 diabetes (T2DM). Method: This observational study consecutively enrolled T2DM scheduled for a colonoscopy. Participants were prospectively separated into the liraglutide group (n = 120), sitagliptin group (n = 120), and control group (n = 120) based on the current hypoglycemic regimen. 3L split-dose polyethylene glycol regimens were used for bowel preparation. Experienced gastrointestinal endoscopists conducted colonoscopies. Lawrance Bowel-Preparation Tolerability Questionnaire and Boston Bowel Preparation Scale (BBPS) were conducted to assess bowel cleaning quality, tolerability, and safety. Results: The incidence of inadequate bowel cleaning was 17.5% in the liraglutide group, 20.5% in the sitagliptin group, and 21.7% in the control group. The difference among the three groups was not statistically significant (p = 0.927). Meanwhile, there were no significant differences in the mean BBPS, cecal intubation time, and polyp-detecting rates among the three groups (all p > 0.0.05). Nausea, vomiting, and bloating scores were increased in the liraglutide group compared with the other two groups (p < 0.05), whereas most were mild or very mild. Subgroup analyses showed that the incidence of inadequate bowel cleaning in T2DM with diabetic peripheral neuropathy (DPN) was increased in the liraglutide group compared with the sitagliptin group (61.3% vs. 32.1%, p = 0.022) and control group (61.3% vs. 32.8%, p = 0.025). Conclusion: GLP-1RA liraglutide or DPP-4i sitagliptin did not significantly increase the incidence of inadequate bowel cleaning and gastrointestinal symptoms during bowel preparation. Liraglutide may increase the incidence of inadequate bowel preparation in patients with DPN. This study reveal that more attention and aggressive bowel preparation regimens should be given to the T2DM with DPN. Clinical Trial Registration: (https://www.chictr.org.cn/index.aspx), identifier (ChiCTR2200056148).