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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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Aim: To evaluate gastric emptying (GE) and the glycaemic response to a 75‐g oral glucose load in newly diagnosed, treatment‐naïve Han Chinese with type 2 diabetes (T2D) before insulin pump therapy, after 4 weeks of insulin pump therapy, and 12–15 months after insulin pump therapy. Materials and Methods: Twenty participants with T2D (baseline glycated haemoglobin [± SD] 10.7% [± 1.2%] 93 [± 10] mmol/mol) ingested a 75‐g glucose drink containing 150 mg 13C‐acetate, to determine the gastric half‐emptying time, and underwent assessment of plasma glucose and serum insulin, C‐peptide and glucagon‐like peptide‐1 (GLP‐1) over 180 min before and after 4 weeks of insulin pump therapy (discontinued for 48 h before re‐assessment). Data were compared to those in 19 healthy participants matched for sex and age. After 12–15 months, GE was re‐measured in 14 of the T2D participants. Results: At baseline, participants with T2D exhibited substantially augmented fasting and post‐glucose glycaemia, diminished insulin secretion, and more rapid GE (p < 0.05 each), but comparable GLP‐1, compared to healthy participants. Following insulin pump therapy, insulin secretion increased, GLP‐1 secretion was attenuated, fasting and post‐glucose glycaemia were lower, and GE was slowed (p < 0.05 each). The slowing of GE in T2D participants was sustained over 12–15 months of follow‐up. Conclusions: In newly diagnosed Han Chinese with T2D, GE is often accelerated despite poor glycaemic control and is slowed by short‐term insulin pump therapy. The effect on GE is maintained for at least 12 months. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background: The pattern of the plasma glucose response curve during an oral glucose tolerance test (OGTT) is of prognostic significance with "biphasic" when compared with "monophasic" patterns being associated with greater insulin sensitivity/secretion and a reduced risk of progression to diabetes. The relationships of the glucose response curves with gastric emptying and incretin hormone secretion are not known. Methods: Thirty-six adults (age > 65 years) without known diabetes consumed a 300 mL drink containing 75 g glucose and 150 mg C13-acetate at baseline and follow-up after 5.8 ± 0.1 years. Plasma glucose, glucagon-like peptide-1 (GLP-1), glucose independent insulinotropic polypeptide (GIP) and insulin were measured, and participants classified according to the pattern of their glucose response. Gastric emptying was measured on breath samples (stable isotope breath test). Results: At baseline, 22 participants had a "monophasic" and 14 a "biphasic" glucose response. The 1 h plasma glucose response curve was greater and the GLP-1 AUC0–120 min and insulin secretion lower in the monophasic group. There were no differences in gastric emptying, GIP or insulin sensitivity. At the follow-up, the 1 h glucose response curve was greater again, while GLP-1 AUC0–120 min was lower in the monophasic group. Conclusions: A biphasic curve is associated with a higher 60 min glucose response curve and increases in GLP-1, but no difference in either GIP or gastric emptying. [ABSTRACT FROM AUTHOR]

Context: Premenopausal women are at a lower risk of type 2 diabetes (T2D) compared to men, but the underlying mechanism(s) remain elusive. The secretion of the incretin hormones, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), from the small intestine is a major determinant of glucose homeostasis and may be influenced by sex. Objectives: This study compared blood glucose and plasma insulin and incretin responses to intraduodenal glucose infusions in healthy young males and females. Design: In Study 1, 9 women and 20 men received an intraduodenal glucose infusion at 2 kcal/min for 60 minutes. In Study 2, 10 women and 26 men received an intraduodenal glucose at 3 kcal/min for 60 minutes. Venous blood was sampled every 15 minutes for measurements of blood glucose and plasma insulin, GLP-1 and GIP. Results: In response to intraduodenal glucose at 2 kcal/min, the incremental area under the curve between t = 0-60 minutes (iAUC0-60min) for blood glucose and plasma GIP did not differ between the 2 groups. However, iAUC0-60min for plasma GLP-1 (P = 0.016) and insulin (P = 0.011) were ~2-fold higher in women than men. In response to intraduodenal glucose at 3 kcal/min, iAUC0-60min for blood glucose, plasma GIP, and insulin did not differ between women and men, but GLP-1 iAUC0-60min was 2.5-fold higher in women (P = 0.012). Conclusion: Healthy young women exhibit comparable GIP but a markedly greater GLP-1 response to intraduodenal glucose than men. This disparity warrants further investigations to delineate the underlying mechanisms and may be of relevance to the reduced risk of diabetes in premenopausal women when compared to men. [ABSTRACT FROM AUTHOR]

Aim: To investigate whether co‐ingestion of dietary protein with, or before, carbohydrate may be a useful strategy to reduce postprandial hyperglycaemia in older men with type 2 diabetes (T2D). Materials and Methods: Blood glucose, plasma insulin and glucagon concentrations were measured for 180 minutes following ingestion of a drink containing 30 g of glucose (G; 120 kcal), 30 g of whey protein (120 kcal), 30 g of glucose plus 30 g of whey protein (GP; 240 kcal), or control (~2 kcal) in older men with T2D (n = 10, 77 ± 1 years; 31 ± 1.7 kg/m2) and without T2D (n = 10, 78 ± 2 years; 27 ± 1.4 kg/m2). Mixed model analysis was used. Results: GP versus G markedly reduced the increase in blood glucose concentrations (P <.001) and had a synergistic effect on the increase in insulin concentrations (P <.001), in men both with and without T2D. Glucose concentrations were higher in men with T2D compared with those without T2D, whereas insulin and glucagon concentrations were largely unaffected by the presence of T2D. Gastric emptying was faster in men with T2D than in those without T2D. Conclusions: The ability of whey protein to reduce carbohydrate‐induced, postprandial hyperglycaemia is retained in older men with T2D compared with those without T2D, and whey protein supplementation may be a useful strategy in the prevention and management of T2D in older people. [ABSTRACT FROM AUTHOR]

Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are used in the treatment of type 2 diabetes mellitus. However, the effects of GLP-1 RAs on glycemic control and body weight vary. In this commentary, the authors explain how this variability may stem from the medications' impact on gastric motility and upper gastrointestinal symptoms. They further underscore the importance of assessing gastric emptying and gastrointestinal symptoms using validated instruments. [ABSTRACT FROM AUTHOR]

Introduction Breath tests utilising13 C-labelled substrates for the assessment of gastric emptying have been applied widely. Wagner-Nelson analysis is a pharmacokinetic model that can be utilised to generate a gastric emptying curve from the %13 CO2 measured in breath samples. We compared Wagner-Nelson analysis with (i) scintigraphy and (ii) conventional breath test modelling to quantify gastric emptying in type 2 diabetes. Methods Thirteen patients (age 68.1±1.5 years, body mass index 31.0±0.9 kg/m2 , HbA1c 6.3±0.2%) consumed a mashed potato meal comprising 65 g powdered potato, 20 g glucose, 250 ml water, an egg yolk labelled with 100 μL13 C-octanoic acid and 20MBq99m Tc-calcium phytate. Scintigraphic data were acquired and breath samples collected for 4 hours after the meal. Gastric emptying curves were derived based on each technique; the 50% emptying time and intragastric retention at 60 min were also calculated. Results With Wagner-Nelson analysis, a Kel =0.60 (the elimination constant) best approximated the scintigraphic gastric emptying curve. There was a relationship between the T50 calculated with scintigraphy and by both Wagner-Nelson Kel =0.60 (r2 =0.45, P<0.05) and conventional analysis (r2 =0.44, P<0.05). There was no significant difference in the 50% gastric emptying time for scintigraphy (68.5±4.8 min) and Wagner-Nelson Kel =0.60 (71.3±4.5 min), however, the 50% gastric emptying time calculated by conventional analysis was much greater at 164.7±6.0 min (P<0.001). Conclusion In type 2 diabetes, gastric emptying of a mashed potato meal measured using a13 C-octanoic acid breath test analysed with Wagner-Nelson Kel =0.60 closely reflects measurements obtained with scintigraphy, whereas, in absolute terms, the conventional breath test analysis does not. [ABSTRACT FROM AUTHOR]

Context The relationships of gastric emptying (GE) with the glycemic response at 120 minutes, glucagon-like peptide-1 (GLP-1), and insulin secretion following a glucose load in type 2 diabetes (T2D) are uncertain. Objective: We evaluated the relationship of plasma glucose, GLP-1, and insulin secretion with GE of a 75-g oral glucose load in T2D. Design: Single-center, cross-sectional, post hoc analysis. Setting: Institutional research center. Participants: 43 individuals with T2D age 65.6 ± 1.1 years, hemoglobin A1c 7.2 ± 1.0%, median duration of diabetes 5 years managed by diet and/or metformin. Intervention: Participants consumed the glucose drink radiolabeled with 99mTc-phytate colloid following an overnight fast. GE (scintigraphy), plasma glucose, GLP-1, insulin, and C-peptide were measured between 0 and 180 minutes. Main Outcome Measures: The relationships of the plasma glucose at 120 minutes, plasma GLP-1, and insulin secretion (calculated by Δinsulin0-30/Δglucose0-30 and ΔC-peptide0-30/Δglucose0-30) with the rate of GE (scintigraphy) were evaluated. Results: There were positive relationships of plasma glucose at 30 minutes (r = 0.56, P < 0.001), 60 minutes (r = 0.57, P < 0.001), and 120 minutes (r = 0.51, P < 0.001) but not at 180 minutes (r = 0.13, P = 0.38), with GE. The 120-minute plasma glucose and GE correlated weakly in multiple regression models adjusting for age, GLP-1, and insulin secretion (P = 0.04 and P = 0.06, respectively). There was no relationship of plasma GLP-1 with GE. Multiple linear regression analysis indicated that there was no significant effect of GE on insulin secretion. Conclusion: In T2D, while insulin secretion is the dominant determinant of the 120-minute plasma glucose, GE also correlates. Given the relevance to interpreting the results of an oral glucose tolerance test, this relationship should be evaluated further. There appears to be no direct effect of GE on either GLP-1 or insulin secretion. [ABSTRACT FROM AUTHOR]

Aim: To determine the serum bile acid (BA) response to 75‐g oral glucose in individuals without diabetes, and whether this is attenuated in patients with 'early' type 2 diabetes (T2D) and related to the glycaemic response at 2 hours in either group. Methods: Forty newly diagnosed, treatment‐naïve Han Chinese T2D subjects and 40 age‐, gender‐, and body mass index‐matched controls without T2D ingested a 75‐g glucose drink after an overnight fast. Plasma glucose and serum concentrations of total and individual BAs, fibroblast growth factor‐19 (FGF‐19), total glucagon‐like peptide‐1 (GLP‐1), and insulin, were measured before and 2 hours after oral glucose. Results: Fasting total BA levels were higher in T2D than control subjects (P <.05). At 2 hours, the BA profile exhibited a shift from baseline in both groups, with increases in conjugated BAs and/or decreases in unconjugated BAs. There were increases in total BA and FGF‐19 levels in control (both P <.05), but not T2D, subjects. Plasma glucose concentrations at 2 hours related inversely to serum total BA levels in control subjects (r = −0.42, P =.006). Total GLP‐1 and the insulin/glucose ratio were increased at 2 hours in both groups, and the magnitude of the increase was greater in control subjects. Conclusions: The serum BA response to a 75‐g oral glucose load is attenuated in patients with 'early' T2D, as is the secretion of FGF‐19 and GLP‐1, while in individuals without T2D it correlates with 2‐hour plasma glucose levels. These observations support a role for BAs in the regulation of postprandial glucose metabolism. [ABSTRACT FROM AUTHOR]

Context: Both gastric emptying and the secretion of glucagon-like peptide-1 (GLP-1) are major determinants of postprandial glycemia in health and type 2 diabetes (T2D). GLP-1 secretion after a meal is dependent on the entry of nutrients into the small intestine, which, in turn, slows gastric emptying. Objective: To define the relationship between gastric emptying and the GLP-1 response to both oral and small intestinal nutrients in subjects with and without T2D. Methods: We evaluated: (i) the relationship between gastric emptying (breath test) and postprandial GLP-1 levels after a mashed potato meal in 73 individuals with T2D; (ii) interindividual variations in GLP-1 response to (a) intraduodenal glucose (4 kcal/min) during euglycemia and hyperglycemia in 11 healthy and 12 T2D, subjects, (b) intraduodenal fat (2 kcal/min) in 15 T2D subjects, and (c) intraduodenal protein (3 kcal/min) in 10 healthy subjects; and (iii) the relationship between gastric emptying (breath test) of 75 g oral glucose and the GLP-1 response to intraduodenal glucose (4 kcal/min) in 21 subjects (9 healthy, 12 T2D). Results: The GLP-1 response to the mashed potato meal was unrelated to the gastric half-emptying time (T50). The GLP-1 responses to intraduodenal glucose, fat, and protein varied substantially between individuals, but intra-individual variation to glucose was modest. The T50 of oral glucose was related directly to the GLP-1 response to intraduodenal glucose (r = 0.65, P = 0.002). Conclusion: In a given individual, gastric emptying is not a determinant of the postprandial GLP-1 response. However, the intrinsic gastric emptying rate is determined in part by the responsiveness of GLP-1 to intestinal nutrients. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background: The rate of gastric emptying and glucoregulatory hormones are key determinants of postprandial glycaemia. Intragastric administration of L-tryptophan slows gastric emptying and reduces the glycaemic response to a nutrient drink in lean individuals and those with obesity. We investigated whether tryptophan decreases postprandial glycaemia and slows gastric emptying in type 2 diabetes (T2D). Methods: Twelve men with T2D (age: 63 ± 2 years, HbA1c: 49.7 ± 2.5 mmol/mol, BMI: 30 ± 1 kg/m2) received, on three separate occasions, 3 g ('Trp-3') or 1.5 g ('Trp-1.5') tryptophan, or control (0.9% saline), intragastrically, in randomised, double-blind fashion, 30 min before a mixed-nutrient drink (500 kcal, 74 g carbohydrates), containing 3 g 3-O-methyl-D-glucose (3-OMG) to assess glucose absorption. Venous blood samples were obtained at baseline, after tryptophan, and for 2 h post-drink for measurements of plasma glucose, C-peptide, glucagon and 3-OMG. Gastric emptying of the drink was quantified using two-dimensional ultrasound. Results: Tryptophan alone stimulated C-peptide (P = 0.002) and glucagon (P = 0.04), but did not affect fasting glucose. In response to the drink, Trp-3 lowered plasma glucose from t = 15–30 min and from t = 30–45 min compared with control and Trp-1.5, respectively (both P < 0.05), with no differences in peak glucose between treatments. Gastric emptying tended to be slower after Trp-3, but not Trp-1.5, than control (P = 0.06). Plasma C-peptide, glucagon and 3-OMG increased on all days, with no major differences between treatments. Conclusions: In people with T2D, intragastric administration of 3 g tryptophan modestly slows gastric emptying, associated with a delayed rise, but not an overall lowering of, postprandial glucose. [ABSTRACT FROM AUTHOR]

Midlife Type 2 Diabetes Mellitus (T2DM) is associated with a greater risk of dementia in later life. Peripheral inflammation and its impact on cognition is proposed as one of the pathological mechanisms mediating this link. However, studies have primarily focused on older individuals with established cognitive impairment and a long duration of T2DM. Importantly, knowledge of which individuals with midlife T2DM who are at greatest risk of later cognitive decline is lacking. We examined the cross-sectional relationship between serum levels of 8 pro-inflammatory markers (IL-1β, IL-6, TNF-α, IL-8, MCP-1, CXCL10, IL-12p70, CRP) and performance on a detailed neuropsychological assessment battery in middle-aged adults with uncomplicated T2DM (N = 89; 52 ± 8.1 years, 47% female) and matched healthy controls (N = 50; 52 ± 8.3 years, 59% female). Linear regression was used to analyze associations between serum markers and cognitive performance in the overall cohort, followed by a T2DM∗protein concentration interaction analysis to identify any T2DM-specific effects. We observed a significant T2DM-specific association between serum TNF-α levels and scores on the Paired Associates Learning (PAL) task (β: −3.16, SE: 1.32, p = 0.01, Std. Beta: −0.94), a task with significant working memory demands previously implicated in T2DM-related cognitive dysfunction. However, this did not persist on controlling for multiple testing. We provide exploratory evidence for a significant T2DM-specific relationship between serum TNF-α and memory performance. These findings require further replication and longitudinal analysis with the aim of selecting-out individuals with midlife T2DM at risk of future cognitive decline for potential preventative interventions. [ABSTRACT FROM AUTHOR]

Objective: Tachyphylaxis for slowing of gastric emptying is seen with continuous exposure to glucagon-like peptide 1 (GLP-1). We therefore aimed to establish whether prolonged use of a "short-acting" GLP-1 receptor agonist, lixisenatide, achieves sustained slowing of gastric emptying and reduction in postprandial glycemia.Research Design and Methods: A total of 30 patients with metformin-treated type 2 diabetes underwent assessment of gastric emptying (scintigraphy) and glucose metabolism (dual tracer technique) after a 75-g glucose drink, before and after 8 weeks' treatment with lixisenatide (20 μg subcutaneously daily) or placebo, in a double-blind randomized parallel design.Results: Gastric retention of the glucose drink was markedly increased after lixisenatide versus placebo (ratio of adjusted geometric means for area under the curve [AUC] over 240 min of 2.19 [95% CI 1.82, 2.64], P < 0.001), associated with substantial reductions in the rate of systemic appearance of oral glucose (P < 0.001) and incremental AUC for blood glucose (P < 0.001). Lixisenatide suppressed both glucagon (P = 0.003) and insulin (P = 0.032), but not endogenous glucose production, over 120 min after oral glucose intake. Postprandial glucose lowering over 240 min was strongly related to the magnitude of slowing of gastric emptying by lixisenatide (r = -0.74, P = 0.002) and to the baseline rate of emptying (r = 0.52, P = 0.048) but unrelated to β-cell function (assessed by β-cell glucose sensitivity).Conclusions: Eight weeks' treatment with lixisenatide is associated with sustained slowing of gastric emptying and marked reductions in postprandial glycemia and appearance of ingested glucose. Short-acting GLP-1 receptor agonists therefore potentially represent an effective long-term therapy for specifically targeting postprandial glucose excursions. [ABSTRACT FROM AUTHOR]

Aims: To evaluate the effects of 8 weeks' administration of exenatide (EXE) once weekly on gastric emptying of solids and liquids (using the "gold standard" technique, scintigraphy), glucose absorption and postprandial glycaemia in healthy people. Material and methods: A total of 32 healthy participants were randomized to receive either EXE once weekly (2 mg/wk subcutaneously; six men, 10 women, mean age 59.9 ± 0.9 years, mean body mass index [BMI] 29.6 ± 0.6 kg/m2) or matching placebo (PBO; six men, 10 women, mean age 60.6 ± 1.2 years, mean BMI 29.5 ± 1.0 kg/m2) for 8 weeks. Gastric emptying, nausea (visual analogue scale), and plasma glucose, insulin, C‐peptide and glucagon were measured for 120 min after a solid/liquid meal, comprising 100 g ground beef (radiolabelled with 20 MBq 99mTc‐sulphur colloid) and 150 mL 10% glucose (radiolabelled with 7 MBq 67Ga‐EDTA), and containing 5 g 3‐O‐methyl‐glucose (3‐OMG) as a marker of glucose absorption, at baseline and after 8 weeks' treatment. Results: The study treatments were well tolerated. Scores for nausea were consistently low, with no difference between the EXE once weekly and PBO groups. EXE once weekly slowed gastric emptying of solids (area under the curve [AUC]0–120min: P < 0.05) and liquids (AUC0–120min: P = 0.01) substantially, and attenuated glucose absorption (3‐OMG incremental AUC [iAUC]0–30min: P = 0.001) and the postprandial rise in plasma glucose (iAUC0–30min: P = 0.008). Plasma glucagon at 2 h was reduced by EXE once weekly (P = 0.001). The magnitude of the reduction in plasma glucose at t = 30 min from baseline to 8 weeks with EXE once weekly was related inversely to the 50% emptying time of the glucose drink (r = −0.55, P = 0.03). Conclusions: In healthy participants, 8 weeks' administration of the "long‐acting" glucagon‐like peptide‐1 receptor agonist EXE, slowed gastric emptying of solids and liquids substantially, with consequent reductions in glucose absorption and postprandial glycaemia. [ABSTRACT FROM AUTHOR]

Aims: Glucose-dependent insulinotropic polypeptide (GIP) is released primarily from the proximal small intestine and glucagon-like peptide-1 (GLP-1) from the more distal small intestine and colon. Their relative importance to the incretin effect in health has been contentious in the past, although it now appears that GIP has the dominant role. It is uncertain whether there is a relationship between GIP and GLP-1 secretion. We aimed to evaluate the relationship between plasma GIP and GLP-1 responses to a 75-g oral glucose load in individuals with normal (NGT) and impaired glucose tolerance (IGT). Methods: One hundred healthy subjects had measurements of blood glucose, serum insulin, plasma GIP and GLP-1 concentrations for 240 min after a 300 mL drink containing 75 g glucose. Results: Fifty had NGT and 41 IGT; 9 had type 2 diabetes and were excluded from analysis. In both groups, there were increases in plasma GIP and GLP-1 following the glucose drink, with no difference in the magnitude of the responses between t = 0–240 min. There was a weak relationship between the iAUC0–240 min for GIP and GLP-1 in the combined (r = 0.23, P = 0.015) and in the IGT (r = 0.34, P = 0.01), but not in the NGT (r = 0.15, P = 0.14) group. Conclusions: There is a weak relationship between oral glucose-induced GIP and GLP-1 secretions in non-diabetic subjects. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the effects of the dipeptidyl peptidase‐4 (DPP‐4) inhibitor vildagliptin on glycaemic and energy expenditure responses during intraduodenal fat infusion, as well as the contribution of endogenous glucagon‐like peptide‐1 (GLP‐1) signalling, in people with type 2 diabetes (T2DM). Methods: A total of 15 people with T2DM managed by diet and/or metformin (glycated haemoglobin 49.3 ± 2.1 mmol/mol) were studied on three occasions (two with vildagliptin and one with placebo) in a double‐blind, randomized, crossover fashion. On each day, vildagliptin 50 mg or placebo was given orally, followed by intravenous exendin (9–39) 600 pmol/kg/min, on one of the two vildagliptin treatment days, or 0.9% saline over 180 minutes. At between 0 and 120 minutes, a fat emulsion was infused intraduodenally at 2 kcal/min. Energy expenditure, plasma glucose and glucose‐regulatory hormones were evaluated. Results: Intraduodenal fat increased plasma GLP‐1 and glucose‐dependent insulinotropic polypeptide (GIP), insulin and glucagon, and energy expenditure, and decreased plasma glucose (all P < 0.05). On the two intravenous saline days, plasma glucose and glucagon were lower, plasma intact GLP‐1 was higher (all P < 0.05), and energy expenditure tended to be lower after vildagliptin (P = 0.08) than placebo. On the two vildagliptin days, plasma glucose, glucagon and GLP‐1 (both total and intact), and energy expenditure were higher during intravenous exendin (9–39) than saline (all P < 0.05). Conclusions: In well‐controlled T2DM during intraduodenal fat infusion, vildagliptin lowered plasma glucose and glucagon, and tended to decrease energy expenditure, effects that were mediated by endogenous GLP‐1. [ABSTRACT FROM AUTHOR]

We believe that the use of the paracetamol technique in isolation to evaluate the effects of GLP-1RAs on gastric emptying in humans should be abandoned and that scintigraphic measurement, using a standardized technique, should represent a mandatory regulatory requirement in the development of this drug class, including oral semaglutide. We have also pointed out that it is incorrect to suggest that a reduction in the AUC 0 to 1 hours, but not the AUC 0 to 5 hours, for paracetamol, indicates that an effect to slow gastric emptying is only sustained for 1 hour,2 simply because it may be anticipated that all the paracetamol will eventually be absorbed. [Extracted from the article]

Aims: To determine the effects of the dipeptidyl peptidase‐4 inhibitor, sitagliptin, on gastric emptying (GE) of a high‐carbohydrate meal and associated glycaemic and blood pressure (BP) responses in type 2 diabetes mellitus (T2DM). Materials and Methods: Fourteen patients with T2DM (nine men, five women; age 67.8 ± 1.5 years; body mass index 31.2 ± 0.9 kg/m2; T2DM duration: 4.2 ± 0.9 years; glycated haemoglobin: 46 ± 1.8 mmol/mol [6.4% ± 0.2%]), managed by diet and/or metformin, underwent concurrent measurements of GE, BP and plasma glucose for 240 minutes after ingestion of a radiolabelled mashed potato meal after receiving sitagliptin (100 mg) or placebo in randomized, double‐blind, crossover fashion on 2 consecutive days. Results: Sitagliptin reduced postprandial plasma glucose (P < .005) without affecting GE (P =.88). The magnitude of the glucose‐lowering effect (change in incremental area under the curve0–240 min from placebo to sitagliptin) was related to GE (kcal/min) on placebo (r = 0.68, P =.008) There was a comparable fall in systolic BP (P =.80) following the meal, with no difference between the 2 days. Conclusions: In T2DM, while sitagliptin has no effect on either GE or postprandial BP, its ability to lower postprandial glucose are dependent on the basal rate of GE. [ABSTRACT FROM AUTHOR]

In 2018, the American Diabetes Association commissioned an expert consensus report on the role of nutrition in the management of diabetes and the prevention of type 2 diabetes. The resulting document, published in May 2019, confirms what many healthcare professionals will have seen in their practice: people with diabetes can make a huge difference to their condition through dietary change and managing weight effectively. In this article, the authors offer a condensed summary of the 24-page report and its 345 references, including the main dietary messages for healthcare professionals. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the effects of the prandial glucagon‐like peptide‐1 receptor agonist lixisenatide on gastric emptying and blood pressure (BP) and superior mesenteric artery (SMA) blood flow, and the glycaemic responses to a 75‐g oral glucose load in healthy people and those with type 2 diabetes (T2DM). Materials and methods: Fifteen healthy participants (nine men, six women; mean ± SEM age 67.2 ± 2.3 years) and 15 participants with T2DM (nine men, six women; mean ± SEM age 61.9 ± 2.3 years) underwent measurement of gastric emptying, BP, SMA flow and plasma glucose 180 minutes after a radiolabelled 75‐g glucose drink on two separate days. All participants received lixisenatide (10 μg subcutaneously) or placebo in a randomized, double‐blind, crossover fashion 30 minutes before the glucose drink. Results: Lixisenatide slowed gastric emptying (retention at 120 minutes, P < 0.01), attenuated the rise in SMA flow (P < 0.01) and markedly attenuated the decrease in systolic BP (area under the curve [AUC] 0‐120 minutes, P < 0.001) compared to placebo in healthy participants and those with T2DM. Plasma glucose (incremental AUC 0‐120 minutes) was greater in participants with T2DM (P < 0.005) than in healthy participants, and lower after lixisenatide in both groups (P < 0.001). Conclusions: In healthy participants and those with T2DM, the marked slowing of gastric emptying of glucose induced by lixisenatide was associated with attenuation of the increments in glycaemia and SMA flow and decrease in systolic BP. Accordingly, lixisenatide may be useful in the management of postprandial hypotension. [ABSTRACT FROM AUTHOR]

Metformin has been shown to modulate the cardiovascular response to intraduodenal glucose in patients with type 2 diabetes (T2DM), and may have the capacity to regulate postprandial blood pressure (BP), which is often inadequately compensated in T2DM, resulting in postprandial hypotension. In the present study, we evaluated the acute effects of metformin on the BP and heart rate (HR) responses to oral glucose in patients with T2DM. Ten diet‐controlled T2DM patients were evaluated on two occasions in a double‐blind, randomized, crossover design. Participants received either metformin 1 g or saline (control) intraduodenally 60 minutes before ingesting a 50 g glucose drink labelled with 150 mg 13C‐acetate. BP, HR, plasma glucagon‐like peptide‐1 (GLP‐1) and gastric emptying (breath test) were evaluated over 180 minutes. Systolic and diastolic BP decreased and HR increased after oral glucose (P < 0.001 for all) on both days. Metformin attenuated the fall in systolic BP (P < 0.001), increased plasma GLP‐1 concentrations (P < 0.05) and slowed gastric emptying (P < 0.05) without significantly affecting diastolic BP or HR. In conclusion, metformin acutely attenuates the hypotensive response to oral glucose, associated with augmented GLP‐1 secretion and delayed gastric emptying, effects potentially relevant to its favourable cardiovascular profile. [ABSTRACT FROM AUTHOR]

Aims: To evaluate the effects of 12 weeks of treatment with a whey/guar preload on gastric emptying, postprandial glycaemia and glycated haemoglobin (HbA1c) levels in people with type 2 diabetes (T2DM). Materials and methods: A total of 79 people with T2DM, managed on diet or metformin (HbA1c 49 ± 0.7 mmol/mol [6.6 ± 0.1%]), were randomized, in single‐blind fashion, to receive 150 mL flavoured preloads, containing either 17 g whey protein plus 5 g guar (n = 37) or flavoured placebo (n = 42), 15 minutes before two meals, each day for 12 weeks. Blood glucose and gastric emptying (breath test) were measured before and after a mashed potato meal at baseline (without preload), and after the preload at the beginning (week 1) and end (week 12) of treatment. HbA1c levels, energy intake, weight and body composition were also evaluated. Results: Gastric emptying was slower (P < 0.01) and postprandial blood glucose levels lower (P < 0.05) with the whey/guar preload compared to placebo preload, and the magnitude of reduction in glycaemia was related to the rate of gastric emptying at both week 1 (r = −0.54, P < 0.001) and week 12 (r = −0.54, P < 0.0001). At the end of treatment, there was a 1 mmol/mol [0.1%] reduction in HbA1c in the whey/guar group compared to the placebo group (49 ± 1.0 mmol/mol [6.6 ± 0.05%] vs. 50 ± 0.8 mmol/mol [6.7 ± 0.05%]; P < 0.05). There were no differences in energy intake, body weight, or lean or fat mass between the groups. Conclusions: In patients with well‐controlled T2DM, 12 weeks' treatment with a low‐dose whey/guar preload, taken twice daily before meals, had sustained effects of slowing gastric emptying and reducing postprandial blood glucose, which were associated with a modest reduction in HbA1c, without causing weight gain. [ABSTRACT FROM AUTHOR]

Objective: Cells releasing glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) are distributed predominately in the proximal and distal gut, respectively. Hence, the region of gut exposed to nutrients may influence GIP and GLP-1 secretion and impact on the incretin effect and gastrointestinal-mediated glucose disposal (GIGD). We evaluated glycemic and incretin responses to glucose administered into the proximal or distal small intestine and quantified the corresponding incretin effect and GIGD in health and type 2 diabetes mellitus (T2DM).Research Design and Methods: Ten healthy subjects and 10 patients with T2DM were each studied on four occasions. On two days, a transnasal catheter was positioned with infusion ports opening 13 cm and 190 cm beyond the pylorus, and 30 g glucose with 3 g 3-O-methylglucose (a marker of glucose absorption) was infused into either site and 0.9% saline into the alternate site over 60 min. Matching intravenous isoglycemic clamp studies were performed on the other two days. Blood glucose, serum 3-O-methylglucose, and plasma hormones were evaluated over 180 min.Results: In both groups, blood glucose and serum 3-O-methylglucose concentrations were higher after proximal than distal glucose infusion (all P < 0.001). Plasma GLP-1 increased minimally after proximal, but substantially after distal, glucose infusion, whereas GIP increased promptly after both infusions, with concentrations initially greater, but less sustained, with proximal versus distal infusion (all P < 0.001). Both the incretin effect and GIGD were less with proximal than distal glucose infusion (both P ≤ 0.009).Conclusions: The distal, as opposed to proximal, small intestine is superior in modulating postprandial glucose metabolism in both health and T2DM. [ABSTRACT FROM AUTHOR]

Aims: The gastrointestinal tract, particularly the lower gut, may be key to the anti‐diabetic action of metformin. We evaluated whether administration of metformin into the distal, vs the proximal, small intestine would be more effective in lowering plasma glucose by stimulating glucagon‐like pepetide‐1 (GLP‐1) and/or slowing gastric emptying (GE) in type 2 diabetes (T2DM). Materials and methods: Ten diet‐controlled T2DM patients were studied on three occasions. A transnasal catheter was positioned with proximal and distal infusion ports located 13 and 190 cm beyond the pylorus, respectively. Participants received infusions of (a) proximal + distal saline (control), (b) proximal metformin (1000 mg) + distal saline or (c) proximal saline + distal metformin (1000 mg) over 5 minutes, followed 60 minutes later by a glucose drink containing 50 g glucose and 150 mg 13C‐acetate. "Arterialized" venous blood and breath samples were collected over 3 hours for measurements of plasma glucose, GLP‐1, insulin and glucagon, and GE, respectively. Results: Compared with control, both proximal and distal metformin reduced plasma glucose and augmented GLP‐1 responses to oral glucose comparably (P < 0.05 each), without affecting plasma insulin or glucagon. GE was slower after proximal metformin than after control (P < 0.05) and tended to be slower after distal metformin, without any difference between proximal and distal metformin. Conclusions: In diet‐controlled T2DM patients, glucose‐lowering via a single dose of metformin administered to the upper and lower gut was comparable and was associated with stimulation of GLP‐1 and slowing of GE. These observations suggest that the site of gastrointestinal administration is not critical to the glucose‐lowering capacity of metformin. [ABSTRACT FROM AUTHOR]

However, in both studies, after continuous administration, gastric emptying was still slowed substantially by GLP-1.12,13 Recent studies, using scintigraphy, have established that the "long-acting" GLP-1RAs, exenatide once-weekly11 and liraglutide,14 do slow emptying with chronic administration, albeit probably less than "short-acting" GLP-1RAs. A study reported in abstract form, in which gastric emptying was measured by scintigraphy, suggests that dulaglutide has a sustained effect to slow gastric emptying in T2DM.18 The effects of subcutaneous and oral semaglutide on gastric emptying, regretfully, have only been assessed using the paracetamol test.19,20 In obese subjects given semaglutide (1 mg/week subcutaneous for 12 weeks), plasma paracetamol levels were 27% less in the first hour.19 It was suggested (we believe incorrectly) that the slowing of emptying is only modest. Dahl et al.20 reported, in abstract form, the effect of oral semaglutide (14 mg) on paracetamol absorption in T2DM; the AUC 0-1 h for plasma paracetamol was reduced by 31%; the AUC 0-5 h was not provided. The comprehensive study by Urva et al.2 evaluated the effect of the dual glucose-dependent insulinotropic polypeptide and GLP-1RA, tirzepatide, using the paracetamol technique, in humans with and without T2DM, and in comparison with the effects of semaglutide and dulaglutide. [Extracted from the article]

Objective: To evaluate effects of vildagliptin and metformin on blood pressure (BP) and heart rate (HR) responses to intraduodenal (ID) glucose in diet-controlled type 2 diabetes.Research Design and Methods: Study A compared vildagliptin (50 mg) and placebo, given 60 min before a 120-min ID glucose infusion at 2 or 4 kcal/min (ID2 or ID4) in 16 patients. Study B compared metformin (850 mg) and placebo, given 30 min before ID2 over 120 min in 9 patients.Results: Systolic (P = 0.002) and diastolic (P < 0.001) BP were lower and HR greater (P = 0.005) after vildagliptin compared with placebo, without interaction between vildagliptin and the glucose infusion rate. In contrast, HR was greater after metformin than placebo (P < 0.001), without any difference in systolic or diastolic BP.Conclusions: Vildagliptin reduces BP and increases HR, whereas metformin increases HR without affecting BP during ID glucose infusion in type 2 diabetes. These distinct cardiovascular profiles during enteral nutrient exposure may have implications for postprandial hypotension. [ABSTRACT FROM AUTHOR]

Objective: Obesity and type 2 diabetes mellitus are risk factors for developing Alzheimer disease. Overlapping patterns of metabolic dysfunction may be common molecular links between these complex diseases. Amyloid-β (Aβ) precursor protein and associated β- and γ-secretases are expressed in adipose tissue. Aβ precursor protein is up-regulated with obesity and correlated to insulin resistance. Aβ may be secreted by adipose tissue, its production may be regulated through metabolic pathways, and Aβ may exert effects on adipose tissue insulin receptor signaling.Methods: Human stromal-vascular cells and differentiated adipocytes were cultured with different combinations of glucose and insulin and then assayed for Aβ in conditioned media. Aβ was measured in vivo using adipose tissue microdialysis.Results: Aβ secretion was increased by glucose and insulin in vitro. Adipose tissue microdialysates contained Aβ. Adipocytes treated with Aβ had decreased expression of insulin receptor substrate-2 and reduced Akt-1 phosphorylation.Conclusions: Aβ was made by adipose tissue cells in vitro at concentrations similar to in vivo measurements. Regulation of Aβ production by glucose and insulin and effects of Aβ on the insulin receptor pathway suggest similar cellular mechanisms may exist between neuronal dysfunction in Alzheimer disease and adipose dysfunction in type 2 diabetes. [ABSTRACT FROM AUTHOR]

Objective: Nutrient "preloads" given before meals can attenuate postprandial glycemic excursions, at least partly by slowing gastric emptying and stimulating secretion of the incretins (i.e., glucagon-like peptide-1 [GLP-1] and glucose-dependent insulinotropic polypeptide [GIP]). This study was designed to evaluate whether a protein preload could improve the efficacy of the dipeptidyl peptidase-4 (DPP-4) inhibitor vildagliptin to increase incretin concentrations, slow gastric emptying, and lower postprandial glycemia in type 2 diabetes.Research Design and Methods: Twenty-two patients with type 2 diabetes treated with metformin were studied on four occasions, receiving either 50 mg vildagliptin (VILD) or placebo (PLBO) on both the evening before and the morning of each study day. The latter dose was followed after 60 min by a preload drink containing either 25 g whey protein (WHEY) or control flavoring (CTRL), and after another 30 min by a (13)C-octanoate-labeled mashed potato meal. Plasma glucose and hormones, and gastric emptying, were evaluated.Results: Compared with PLBO/CTRL, PLBO/WHEY reduced postprandial peak glycemia, increased plasma insulin, glucagon, and incretin hormones (total and intact), and slowed gastric emptying, whereas VILD/CTRL reduced both the peak and area under the curve for glucose, increased plasma intact incretins, and slowed gastric emptying but suppressed plasma glucagon and total incretins (P < 0.05 each). Compared with both PLBO/WHEY and VILD/CTRL, VILD/WHEY was associated with higher plasma intact GLP-1 and GIP, slower gastric emptying, and lower postprandial glycemia (P < 0.05 each).Conclusions: In metformin-treated type 2 diabetes, a protein preload has the capacity to enhance the efficacy of vildagliptin to slow gastric emptying, increase plasma intact incretins, and reduce postprandial glycemia. [ABSTRACT FROM AUTHOR]

The short-acting glucagon-like peptide 1 receptor agonist exenatide reduces postprandial glycemia, partly by slowing gastric emptying, although its impact on small intestinal function is unknown. In this study, 10 healthy subjects and 10 patients with type 2 diabetes received intravenous exenatide (7.5 μg) or saline (-30 to 240 min) in a double-blind randomized crossover design. Glucose (45 g), together with 5 g 3-O-methylglucose (3-OMG) and 20 MBq (99m)Tc-sulfur colloid (total volume 200 mL), was given intraduodenally (t = 0-60 min; 3 kcal/min). Duodenal motility and flow were measured using a combined manometry-impedance catheter and small intestinal transit using scintigraphy. In both groups, duodenal pressure waves and antegrade flow events were fewer, and transit was slower with exenatide, as were the areas under the curves for serum 3-OMG and blood glucose concentrations. Insulin concentrations were initially lower with exenatide than with saline and subsequently higher. Nausea was greater in both groups with exenatide, but suppression of small intestinal motility and flow was observed even in subjects with little or no nausea. The inhibition of small intestinal motor function represents a novel mechanism by which exenatide can attenuate postprandial glycemia. [ABSTRACT FROM AUTHOR]

Background: Resveratrol has been reported to lower glycemia in rodent models of type 2 diabetes associated with the stimulation of glucagon-like peptide 1 (GLP-1), which is known to slow gastric emptying, stimulate insulin secretion, and suppress glucagon secretion and energy intake. Objective: We evaluated the effects of 5 wk of resveratrol treatment on GLP-1 secretion, gastric emptying, and glycemic control in type 2 diabetes. Design: Fourteen patients with diet-controlled type-2 diabetes [mean ± SEM glycated hemoglobin (HbA1c): 6.4 ± 0.2% (46.4 ± 2.2 mmol/mol)] received resveratrol (500 mg twice daily) or a placebo over two 5-wk intervention periods with a 5-wk washout period in between in a double-blind, randomized, crossover design. Before and after each intervention period (4 visits), body weight and HbA1c were measured, and patients were evaluated after an overnight fast with a standardized mashed-potato meal labeled with 100 µg 13C-octanoic acid to measure blood glucose and plasma GLP-1 concentrations and gastric emptying (breath test) over 240 min. Daily energy intake was estimated from 3-d food diaries during the week before each visit. Results: Fasting and postprandial blood glucose and plasma total GLP-1 as well as gastric emptying were similar at each assessment, and the change in each variable from weeks 0 to 5 did not differ between resveratrol and placebo groups. Similarly, changes in HbA1c, daily energy intake, and body weight after 5 wk did not differ between the 2 treatments. Conclusions: In patients with diet-controlled type 2 diabetes, 5 wk of twice-daily 500 mg-resveratrol supplementation had no effect on GLP-1 secretion, glycemic control, gastric emptying, body weight, or energy intake. Our observations do not support the use of resveratrol for improving glycemic control. This trial was registered at www.anzctr.org.au as ACTRN12613000717752. [ABSTRACT FROM AUTHOR]

Acute administration of glucagon-like peptide 1 (GLP-1) and its agonists slows gastric emptying, which represents the major mechanism underlying their attenuation of postprandial glycemic excursions. However, this effect may diminish during prolonged use. We compared the effects of prolonged and intermittent stimulation of the GLP-1 receptor on gastric emptying and glycemia. Ten healthy men received intravenous saline (placebo) or GLP-1 (0.8 pmol/kg * min), as a continuous 24-h infusion ("prolonged"), two 4.5-h infusions separated by 20 h ("intermittent"), and a 4.5-h infusion ("acute") in a randomized, double-blind, crossover fashion. Gastric emptying of a radiolabeled mashed potato meal was measured using scintigraphy. Acute GLP-1 markedly slowed gastric emptying. The magnitude of the slowing was attenuated with prolonged but maintained with intermittent infusions. GLP-1 potently diminished postprandial glycemia during acute and intermittent regimens. These observations suggest that short-acting GLP-1 agonists may be superior to long-acting agonists when aiming specifically to reduce postprandial glycemic excursions in the treatment of type 2 diabetes. [ABSTRACT FROM AUTHOR]

Delayed gastric emptying affects a substantial proportion of patients with long-standing diabetes, and when associated with symptoms and/or disordered glycemic control, affects quality of life adversely. Important clinicopathological insights have recently been gained by the systematic analysis of gastric biopsies from patients with severe diabetic gastroparesis, which may stimulate the development of new therapies in the coming decade. Experience with prokinetic therapies and treatments, such as pyloric botulinum toxin injection and gastric electrical stimulation, has established that relief of symptoms does not correlate closely with acceleration of delayed gastric emptying, and that well-designed controlled trials are essential to determine the efficacy of emerging therapies. [ABSTRACT FROM AUTHOR]

Gastric emptying is a major detenninant of glycemia, gastrointestinal hormone release, and appetite. We determined the effects of different intraduodenal glucose loads on glycemia, insulinemia, glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP) and cholecystokinin (CCK), antropyloroduodenal motility, and energy intake in healthy subjects. Blood glucose, plasma hormone, and antropyloroduodenal motor responses to 120-min intraduodenal infusions of glucose at 1) 1 ("G1"), 2) 2 ("G2"), and 3) 4 ("G4") kcal/min or of 4) saline ("control") were measured in 10 healthy males in double-blind, randomized fashion. Immediately after each infusion, energy intake at a buffet meal was quantified. Blood glucose rose in response to all glucose infusions (P < 0.05 vs. control), with the effect of G4 and G2 being greater than that of G1 (P < 0.05) but with no difference between G2 and G4. The rises in insulin, GLP-1, GIP, and CCK were related to the glucose load (r > 0.82, P < 0.05). All glucose infusions suppressed antral (P < 0.05), but only G4 decreased duodenal, pressure waves (P < 0.01), resulted in a sustained stimulation of basal pyloric pressure (P < 0.01), and decreased energy intake (P < 0.05). In conclusion, variations in duodenal glucose loads have differential effects on blood glucose, plasma insulin, GLP-1, GIP and CCK, antropyloroduodenal motility, and energy intake in healthy subjects. These observations have implications for strategies to minimize postprandial glycemic excursions in type 2 diabetes. [ABSTRACT FROM AUTHOR]

Delayed gastric emptying is frequently observed in patients with longstanding type 1 and type 2 diabetes mellitus. and potentially impacts on upper gastrointestinal symptoms, glycaemic control, nutrition and oral drug absorption. The pathogenesis remains unclear and management strategies are currently suboptimal. Therapeutic strategies focus on accelerating gastric emptying, controlling symptoms and improving glycaemic control. The potential adverse effects of hyperglycaemia on gastric emptying and upper gut symptoms indicate the importance of normalising blood glucose if possible. Nutritional and psychological supports are also important, but often neglected. A number of recent pharmacological and non-pharmacological therapies show promise, including gastric electrical stimulation. As with all chronic illnesses, a multidisciplinary approach to management is recommended, but there are few data regarding long-term outcomes. [ABSTRACT FROM AUTHOR]

See Original Article I here i We read with interest the article by Ahmadizar et al1 that suggests the use of statins may increase the risk of insulin resistance and type 2 diabetes (T2D). Fasting serum taurine-conjugated bile acids are elevated in type 2 diabetes and do not change with intensification of insulin. [Extracted from the article]

Postprandial hypotension occurs frequently in diabetes; the fall in blood pressure is greatest after ingestion of carbohydrate, particularly glucose and, in type 2 diabetes, is related to the rate of gastric emptying. The aim of this study was to determine whether slowing of gastric emptying by guar gum reduces the fall in blood pressure after oral glucose in patients with type 2 diabetes. Eleven type 2 patients managed by diet alone, age 61.9 +/- 1.3 years, had measurements of gastric emptying, blood pressure, blood glucose, and serum insulin on two occasions after ingestion of 300 ml water containing 50 g glucose, with or without 9 g guar gum. The magnitude of the fall in blood pressure was less (P < 0.05) and gastric emptying slower (P < 0.05) after guar. Blood glucose (P < 0.05) and serum insulin (P < 0.01) concentrations were lower after guar. The magnitude of the fall in systolic blood pressure was related to gastric emptying of glucose at 30 min on the control day (r = 0.67, P < 0.05). We conclude that guar gum attenuates the fall in blood pressure after oral glucose in patients with type 2 diabetes mellitus, presumably by slowing glucose absorption. [ABSTRACT FROM AUTHOR]

The study examines the impact of the timing of metformin administration on plasma lactate response to intraduodenal glucose infusion in type 2 diabetes. Results show that administering metformin 60 minutes before glucose infusion led to a 2.1-fold increase in plasma lactate compared to administration at the start of glucose infusion. The study suggests further research is needed to understand how pre-meal metformin administration affects blood glucose control and body weight in type 2 diabetes. The study also highlights the need to consider potential risks of lactic acidosis with pre-meal metformin administration, especially in individuals with impaired liver or kidney function. [Extracted from the article]

Bile acids are cholesterol-derived metabolites with a well-established role in the digestion and absorption of dietary fat. More recently, the discovery of bile acids as natural ligands for the nuclear farnesoid X receptor (FXR) and membrane Takeda G-protein-coupled receptor 5 (TGR5), and the recognition of the effects of FXR and TGR5 signaling have led to a paradigm shift in knowledge regarding bile acid physiology and metabolic health. Bile acids are now recognized as signaling molecules that orchestrate blood glucose, lipid and energy metabolism. Changes in FXR and/or TGR5 signaling modulates the secretion of gastrointestinal hormones including glucagon-like peptide-1 (GLP-1) and peptide YY (PYY), hepatic gluconeogenesis, glycogen synthesis, energy expenditure, and the composition of the gut microbiome. These effects may contribute to the metabolic benefits of bile acid sequestrants, metformin, and bariatric surgery. This review focuses on the role of bile acids in energy intake and body weight, particularly their effects on gastrointestinal hormone secretion, the changes in obesity and T2D, and their potential relevance to the management of metabolic disorders. [ABSTRACT FROM AUTHOR]

OBJECTIVE -- We evaluated whether a whey preload could slow gastric emptying, stimulate incretin hormones, and attenuate postprandial glycemia in type 2 diabetes. RESEARCH DESIGN AND METHODS-- Eight type 2 diabetic patients ingested 350 ml beef soup 30 min before a potato meal; 55 g whey was added to either the soup (whey preload) or potato (whey in meal) or no whey was given. RESULTS -- Gastric emptying was slowest after the whey preload (P < 0.0005). The incremental area under the blood glucose curve was less after the whey preload and whey in meal than after no whey (P < 0.005). Plasma glucose-dependent insulinotropic polypeptide, insulin, and cholecystokinin concentrations were higher on both whey days than after no whey, whereas glucagon-like peptide 1 was greatest after the whey preload (P < 0.05). CONCLUSIONS-- Whey protein consumed before a carbohydrate meal can stimulate insulin and incretin hormone secretion and slow gastric emptying, leading to marked reduction in postprandial glycemia in type 2 diabetes. [ABSTRACT FROM AUTHOR]