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.

Comparison of energy intake in critical illness survivors, general medical patients, and healthy volunteers: A descriptive cohort study

BACKGROUND

Intensive care unit (ICU) survivors have reduced oral intake; it is unknown whether intake and associated barriers are unique to this group.

OBJECTIVE

To quantify energy intake and potential barriers in ICU survivors compared with general medical (GM) patients and healthy volunteers.

DESIGN

A descriptive cohort study in ICU survivors, GM patients, and healthy volunteers. Following an overnight fast, participants consumed a 200 ml test-meal (213 kcal) and 180 min later an ad libitum meal to measure energy intake (primary outcome). Secondary outcomes; taste recognition, nutrition-impacting symptoms, malnutrition, and quality of life (QoL). Data are mean ± SD, median (interquartile range [IQR]) or number [percentage]).

RESULTS

Twelve ICU survivors (57 ± 17 years, BMI: 30 ± 6), eight GM patients (69 ± 19 years, BMI: 30 ± 6), and 25 healthy volunteers (58 ± 27 years, BMI: 25 ± 4) were included. Recruitment ceased early because of slow recruitment and SARS-CoV-2. Energy intake was lower in both patient groups than in health (ICU: 289 [288, 809], GM: 426 [336, 592], health: 815 [654, 1165] kcal). Loss of appetite was most common (ICU: 78%, GM: 67%). For ICU survivors, GM patients and healthy volunteers, respectively, severe malnutrition prevalence; 40%, 14%, and 0%; taste identification; 8.5 [7.0, 11.0], 8.5 [7.0, 9.5], and 8.0 [6.0, 11.0]; and QoL; 60 [40-65], 50 [31-55], and 90 [81-95] out of 100.

CONCLUSIONS

Energy intake at a buffet meal is lower in hospital patients than in healthy volunteers but similar between ICU survivors and GM patients. Appetite loss potentially contributes to reduced energy intake.

Impact of the timing of metformin administration on glycaemic and glucagon-like peptide-1 responses to intraduodenal glucose infusion in type 2 diabetes: a double-blind, randomised, placebo-controlled, crossover study

AIMS/HYPOTHESIS

Metformin lowers postprandial glycaemic excursions in individuals with type 2 diabetes by modulating gastrointestinal function, including the stimulation of glucagon-like peptide-1 (GLP-1). The impact of varying the timing of metformin administration on postprandial glucose metabolism is poorly defined. We evaluated the effects of metformin, administered at different intervals before an intraduodenal glucose infusion, on the subsequent glycaemic, insulinaemic and GLP-1 responses in metformin-treated type 2 diabetes.

METHODS

Sixteen participants with type 2 diabetes that was relatively well-controlled by metformin monotherapy were studied on four separate days in a crossover design. On each day, participants were randomised to receive a bolus infusion of metformin (1000 mg in 50 ml 0.9% saline) via a nasoduodenal catheter at t = -60, -30 or 0 min (and saline at the other timepoints) or saline at all timepoints (control), followed by an intraduodenal glucose infusion of 12.56 kJ/min (3 kcal/min) at t = 0-60 min. The treatments were blinded to both participants and investigators involved in the study procedures. Plasma glucose, insulin and total GLP-1 levels were measured every 30 min between t = -60 min and t = 120 min.

RESULTS

There was a treatment-by-time interaction for metformin in reducing plasma glucose levels and increasing plasma GLP-1 and insulin levels (p<0.05 for each). The reduction in plasma glucose levels was greater when metformin was administered at t = -60 or -30 min vs t = 0 min (p<0.05 for each), and the increases in plasma GLP-1 levels were evident only when metformin was administered at t = -60 or -30 min (p<0.05 for each). Although metformin did not influence insulin sensitivity, it enhanced glucose-induced insulin secretion (p<0.05), and the increases in plasma insulin levels were comparable on the 3 days when metformin was given.

CONCLUSIONS/INTERPRETATION

In well-controlled metformin-treated type 2 diabetes, glucose-lowering by metformin is greater when it is given before, rather than with, enteral glucose, and this is associated with a greater GLP-1 response. These observations suggest that administration of metformin before meals may optimise its effect in improving postprandial glycaemic control.

TRIAL REGISTRATION

www.anzctr.org.au ACTRN12621000878875 FUNDING: The study was not funded by a specific research grant.

The herbal preparation, STW5-II, reduces proximal gastric tone and stimulates antral pressures in healthy humans

BACKGROUND

The herbal preparation, STW5-II, improves upper gastrointestinal symptoms, including abdominal fullness, early satiation, and epigastric pain, in patients with functional dyspepsia, and in preclinical models decreases fundic tone and increases antral contractility. The effects of STW5-II on esophago-gastric junction pressure, proximal gastric tone and antropyloroduodenal pressures, disturbances of which may contribute to symptoms associated with disorders of gut-brain interaction, including functional dyspepsia, in humans, have, hitherto, not been evaluated.

METHODS

STW5-II or placebo (matched for color, aroma, and alcohol content) were each administered orally, at the recommended dose (20 drops), to healthy male and female volunteers (age: 27 ± 1 years) in a double-blind, randomized fashion, on two separate occasions, separated by 3-7 days, to evaluate effects on (i) esophago-gastric junction pressures following a standardized meal using solid-state high-resolution manometry (part 1, n = 16), (ii) proximal gastric volume using a barostat (part 2, n = 16), and (iii) antropyloroduodenal pressures assessed by high-resolution manometry (part 3, n = 18), for 120 min (part 1) or 180 min (parts 2, 3).

KEY RESULTS

STW5-II increased maximum intrabag volume (ml; STW5-II: 340 ± 38, placebo: 251 ± 30; p = 0.007) and intrabag volume between t = 120 and 180 min (p = 0.011), and the motility index of antral pressure waves between t = 60 and 120 min (p = 0.032), but had no effect on esophago-gastric junction, pyloric, or duodenal pressures.

CONCLUSIONS & INFERENCES

STW5-II has marked region-specific effects on gastric motility in humans, which may contribute to its therapeutic efficacy in functional dyspepsia.

Serum alanine transaminase is predictive of fasting and postprandial insulin and glucagon concentrations in type 2 diabetes

The liver plays a key role in glucose homeostasis. Serum liver enzyme levels, including alanine transaminase (ALT), aspartate transaminase (AST) and gamma-glutamyl transferase (GGT), are reportedly predictive of the risk of type 2 diabetes (T2D). However, the link between the liver enzyme profile and metabolic derangements in T2D, particularly the secretion of both insulin and glucagon, is not clear. This study evaluated its relationships with glycemia, insulin and glucagon both during fasting and after an oral glucose load or a mixed meal in T2D. 15 healthy and 43 T2D subjects ingested a 75 g glucose drink. 86 T2D subjects consumed a mixed meal. Venous blood was sampled for measurements of blood glucose and plasma insulin, C-peptide and glucagon. Blood glucose, plasma insulin, C-peptide and glucagon concentrations, both fasting and after oral glucose, correlated directly with ALT, while fewer and weaker correlations were observed with GGT or AST. Subgroup analysis in T2D subjects ascertained that plasma insulin, C-peptide and glucagon concentrations after oral glucose were higher with increasing ALT. Similar findings were observed in the T2D subjects who received a mixed meal. In conclusion, serum liver enzyme profile, particularly ALT, reflects dysregulated fasting and nutrient-stimulated plasma insulin and glucagon concentrations in T2D.

A Biphasic Glucose Response during an Oral Glucose Tolerance Test Is Associated with Greater Plasma Insulin and GLP-1 Responses and a Reduction in 1-Hour Glucose but Does Not Relate to the Rate of Gastric Emptying in Healthy, Older Adults

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.

The Adelaide Score: An artificial intelligence measure of readiness for discharge after general surgery

BACKGROUND

This study aimed to examine the performance of machine learning algorithms for the prediction of discharge within 12 and 24 h to produce a measure of readiness for discharge after general surgery.

METHODS

Consecutive general surgery patients at two tertiary hospitals, over a 2-year period, were included. Observation and laboratory parameter data were stratified into training, testing and validation datasets. Random forest, XGBoost and logistic regression models were evaluated. Each ward round note time was taken as a different event. Primary outcome was classification accuracy of the algorithmic model able to predict discharge within the next 12 h on the validation data set.

RESULTS

42 572 ward round note timings were included from 8826 general surgery patients. Discharge occurred within 12 h for 8800 times (20.7%), and within 24 h for 9885 (23.2%). For predicting discharge within 12 h, model classification accuracies for derivation and validation data sets were: 0.84 and 0.85 random forest, 0.84 and 0.83 XGBoost, 0.80 and 0.81 logistic regression. For predicting discharge within 24 h, model classification accuracies for derivation and validation data sets were: 0.83 and 0.84 random forest, 0.82 and 0.81 XGBoost, 0.78 and 0.79 logistic regression. Algorithms generated a continuous number between 0 and 1 (or 0 and 100), representing readiness for discharge after general surgery.

CONCLUSIONS

A derived artificial intelligence measure (the Adelaide Score) successfully predicts discharge within the next 12 and 24 h in general surgery patients. This may be useful for both treating teams and allied health staff within surgical systems.

Disparities in the Glycemic and Incretin Responses to Intraduodenal Glucose Infusion Between Healthy Young Men and Women

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.

Effect of gastric distension with concurrent small intestinal saline or glucose infusion on incretin hormone secretion in healthy individuals: A randomized, controlled, crossover study

AIM

To evaluate the effect of gastric distension, induced using a gastric 'barostat', on the secretion of glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) in the presence and absence of small intestinal nutrients in healthy individuals.

MATERIALS AND METHODS

Eight healthy participants (two females, six males, mean age 69.3 ± 1.2 years, body mass index 23.5 ± 0.8 kg/m2 ) were each studied on four occasions when they received an intraduodenal infusion of either (i) 0.9% saline or (ii) glucose delivered at a rate of 3 kcal/min both with, and without, an intragastric balloon with the pressure set to 8 mmHg above the intragastric minimum distending pressure.

RESULTS

Following intraduodenal saline or glucose infusion, there was no difference in plasma GLP-1 with or without gastric distension (P = 1.00 for both saline and glucose infusions). There was also no difference in plasma GIP with or without gastric distension (P = 1.00 for saline infusion and P = .99 for glucose infusion).

CONCLUSIONS

Gastric distension, either alone or during small intestinal glucose exposure, does not stimulate incretin hormone secretion significantly in healthy humans.

First Direct Measurement Constraining the ^{34}Ar(α,p)^{37}K Reaction Cross Section for Mixed Hydrogen and Helium Burning in Accreting Neutron Stars

The rate of the final step in the astrophysical αp process, the ^{34}Ar(α,p)^{37}K reaction, suffers from large uncertainties due to a lack of experimental data, despite having a considerable impact on the observable light curves of x-ray bursts and the composition of the ashes of hydrogen and helium burning on accreting neutron stars. We present the first direct measurement constraining the ^{34}Ar(α,p)^{37}K reaction cross section, using the Jet Experiments in Nuclear Structure and Astrophysics gas jet target. The combined cross section for the ^{34}Ar,Cl(α,p)^{37}K,Ar reaction is found to agree well with Hauser-Feshbach predictions. The ^{34}Ar(α,2p)^{36}Ar cross section, which can be exclusively attributed to the ^{34}Ar beam component, also agrees to within the typical uncertainties quoted for statistical models. This indicates the applicability of the statistical model for predicting astrophysical (α,p) reaction rates in this part of the αp process, in contrast to earlier findings from indirect reaction studies indicating orders-of-magnitude discrepancies. This removes a significant uncertainty in models of hydrogen and helium burning on accreting neutron stars.

Inter-relationships between gastric emptying and glycaemia: Implications for clinical practice

Gastric emptying (GE) exhibits a wide inter-individual variation and is a major determinant of postprandial glycaemia in health and diabetes; the rise in blood glucose following oral carbohydrate is greater when GE is relatively more rapid and more sustained when glucose tolerance is impaired. Conversely, GE is influenced by the acute glycaemic environment acute hyperglycaemia slows, while acute hypoglycaemia accelerates it. Delayed GE (gastroparesis) occurs frequently in diabetes and critical illness. In diabetes, this poses challenges for management, particularly in hospitalised individuals and/or those using insulin. In critical illness it compromises the delivery of nutrition and increases the risk of regurgitation and aspiration with consequent lung dysfunction and ventilator dependence. Substantial advances in knowledge relating to GE, which is now recognised as a major determinant of the magnitude of the rise in blood glucose after a meal in both health and diabetes and, the impact of acute glycaemic environment on the rate of GE have been made and the use of gut-based therapies such as glucagon-like peptide-1 receptor agonists, which may profoundly impact GE, in the management of type 2 diabetes, has become commonplace. This necessitates an increased understanding of the complex inter-relationships of GE with glycaemia, its implications in hospitalised patients and the relevance of dysglycaemia and its management, particularly in critical illness. Current approaches to management of gastroparesis to achieve more personalised diabetes care, relevant to clinical practice, is detailed. Further studies focusing on the interactions of medications affecting GE and the glycaemic environment in hospitalised patients, are required.

Determinants of blood glucose concentrations following a high carbohydrate meal in type 2 diabetes: A multiple linear regression analysis

This study showed that in relatively well-controlled type 2 diabetes blood glucose levels after a high carbohydrate meal were associated positively with fasting blood glucose, but also positively with gastric emptying in the first hour and negatively with the increments in plasma glucagon-like peptide-1 (GLP-1) in the later postprandial phase.

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

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

Effects of co-ingesting glucose and whey protein on blood glucose, plasma insulin and glucagon concentrations, and gastric emptying, in older men with and without type 2 diabetes

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.

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

Gastric emptying is a major determinant of postprandial blood glucose, accounting for ~35% of variance in peak glucose in both healthy individuals and those with type 2 diabetes. Gastric emptying is frequently disordered in individuals with diabetes (both abnormally delayed and accelerated). Delayed gastric emptying, i.e. diabetic gastroparesis, may be linked to upper gastrointestinal symptoms for which current treatment remains suboptimal; pharmacological acceleration of delayed emptying is only weakly associated with symptom improvement. Accordingly, the relationship between symptoms and delayed gastric emptying is not simply 'cause and effect'. In insulin-treated patients, disordered gastric emptying, even when not associated with gastrointestinal symptoms, can cause a mismatch between the onset of insulin action and the availability of absorbed carbohydrate, leading to suboptimal glycaemic control. In patients with type 2 diabetes, interventions that slow gastric emptying, e.g. glucagon-like peptide-1 receptor agonists, reduce postprandial blood glucose. This review focuses on recent insights into the impact of gastric emptying on postprandial blood glucose, effects of diabetes therapy on gastric emptying and the management of disordered gastric emptying in diabetes. In view of the broad relevance of gastric emptying to diabetes management, it is important that future clinical trials evaluating novel therapies that may affect gastric emptying should quantify the latter with an appropriate technique, such as scintigraphy or a stable isotope breath test.

Measurement of Gastric Emptying Using a 13C-octanoic Acid Breath Test with Wagner-Nelson Analysis and Scintigraphy in Type 2 Diabetes

INTRODUCTION

Breath tests utilising ¹³C-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 % ¹³CO₂ 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 μL ¹³C-octanoic acid and 20MBq ^99mTc-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 K_el=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 K_el=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 K_el=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 a ¹³C-octanoic acid breath test analysed with Wagner-Nelson K_el=0.60 closely reflects measurements obtained with scintigraphy, whereas, in absolute terms, the conventional breath test analysis does not.

One-hour plasma glucose level after a 75 g oral glucose load and its relationship to gastric emptying in survivors of critical illness and stress hyperglycaemia

Objective: A 1-hour plasma glucose level ≥ 8.6 mmol/L in a 75 g oral glucose tolerance test has been strongly associated with increased morbidity and mortality in outpatients without diabetes. Our primary aim was to evaluate the 1-hour plasma glucose level in a 75 g glucose tolerance test in survivors of critical illness with stress hyperglycaemia at 3 months after intensive care unit (ICU) discharge, with the secondary aims to evaluate the 2-hour plasma glucose level, glycated haemoglobin (HbA1c), and gastric emptying. Design:Post hoc analysis of a single-centre, prospective cohort study. Setting: Single-centre, tertiary referral, mixed medical-surgical ICU. Participants: Consecutively admitted patients aged ≥ 18 years who developed stress hyperglycaemia and survived to hospital discharge were eligible. Interventions: Participants returned at 3 months after ICU discharge and underwent a 75 g oral glucose tolerance test. Main outcome measures: One- and 2-hour post load plasma glucose level, HbA1c, and assessment of gastric emptying via an isotope breath test. Results: Thirty-five patients (12 females; mean age, 58.5 years [SD, 10.5]; mean HbA1c, 37.4 mmol/mol [SD, 7.0]) attended the followup. In 32/35 patients (91%) the 1-hour post load plasma glucose level was ≥ 8.6 mmol/L. There was a positive correlation between the plasma glucose level at 1 hour (r2 = 0.21; P = 0.006), but no correlation between the 2-hour glucose level (r2 = 0.006; P = 0.63) and gastric emptying. Conclusion: Glucose intolerance, when defined as 1-hour glucose level ≥ 8.6 mmol/L following a 75 g oral glucose load, persists at 3 months in most survivors of stress hyperglycaemia and is dependent on the rate of gastric emptying. Longitudinal studies to characterise mechanisms underlying dysglycaemia and progression to diabetes in individuals with stress hyperglycaemia are indicated.

Prevalence of Gastrointestinal Symptoms in Chinese Community-Dwelling Adults with and without Diabetes

Background: Gastrointestinal symptoms have been reported to occur frequently in diabetes, but their prevalence in Chinese community-dwelling individuals with diabetes is unknown. The present study aimed to address this issue and explore the risk factors for gastrointestinal symptoms. Methods: A total of 1304 community-dwelling participants (214 with diabetes, 360 with prediabetes and 730 with normoglycemia) were surveyed for gastrointestinal symptoms using the Diabetes Bowel Symptom Questionnaire. Logistic regression analyses were applied to identify risk factors for gastrointestinal symptoms. Results: Of the overall study population, 18.6% reported at least one gastrointestinal symptom, without a significant difference between subjects with normoglycemia (17.7%), prediabetes (19.7%) and diabetes (20.1%). In all three groups, lower gastrointestinal symptoms, particularly diarrhea and constipation, were the most frequent. There was an interaction between age (≥65 years) and diabetes on the prevalence of at least one gastrointestinal symptom (p = 0.01) and of constipation (p = 0.004), with these being most frequent in subjects with diabetes aged ≥ 65 years. After multivariable adjustment, female gender and older age were associated with increased odds of at least one gastrointestinal symptom, specifically lower gastrointestinal symptoms. Older age was also associated with an increase in upper gastrointestinal symptoms. Conclusions: Gastrointestinal symptoms are common in Chinese community-dwelling adults with and without diabetes. Females, and the elderly with diabetes, are at an increased risk of symptoms.

Relationships of Glucose, GLP-1, and Insulin Secretion With Gastric Emptying After a 75-g Glucose Load in Type 2 Diabetes

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.

Cholecystectomy is associated with dysglycaemia: Cross-sectional and prospective analyses

Cholecystectomy has been reported to be associated with increased risk of diabetes in cross-sectional studies. In the current study, we performed both cross-sectional and prospective analyses to examine the association between cholecystectomy and dysglycaemia in Chinese community-dwelling adults. A total of 1612 participants (n = 1564 without cholecystectomy and n = 48 with cholecystectomy) were evaluated for glycaemic status (according to the World Health Organization (WHO) 1999 criteria) and then followed up over ~3.2 years. Percent changes (Δ) in fasting blood glucose and HbA1c from baseline at the follow-up visit were calculated to define glycaemic control as stable (-10% ≤ Δ < 10%), improved (Δ < -10%), or worsened (Δ ≥ 10%). The baseline cross-sectional analyses indicated that cholecystectomy was associated with an increased risk of both prediabetes and diabetes, while the prospective analysis indicated that cholecystectomy was also associated with a greater risk of deterioration in glycaemic control (ΔFPG ≥10% and ΔHbA1c ≥10%) (P < 0.05 for each, both before and after adjusting for potential confounding covariates). These observations suggest that individuals in the Chinese community-dwelling population who have undergone cholecystectomy are at increased risk of dysglycaemia. Further studies are warranted to both delineate the underlying mechanisms and to clarify whether more intense surveillance for future development of diabetes is needed in this group.

Comparative effects of low-carbohydrate, full-strength and low-alcohol beer on gastric emptying, alcohol absorption, glycaemia and insulinaemia in health

AIMS

The aim of this study was to evaluate the comparative effects of low-carbohydrate (LC), full-strength (FS), and low-alcohol (LA) beer on gastric emptying (GE), ethanol absorption, glycaemia and insulinaemia in health.

METHODS

Eight subjects (four male, four female; age: 20.4 ± 0.4 years; BMI 22.7 ± 0.4 kg/m² ) had concurrent measurements of GE, plasma ethanol, blood glucose and plasma insulin for 180 min on three separate occasions after ingesting 600 mL of (i) FS beer (5.0% w/v, 246 kcal, 19.2 g carbohydrate), (ii) LC beer (4.6% w/v, 180 kcal, 5.4 g carbohydrate) and (iii) LA beer (2.6% w/v, 162 kcal, 17.4 g carbohydrate) labelled with 20 MBq 99mTc-calcium phytate, in random order.

RESULTS

There was no difference in the gastric 50% emptying time (T50) (FS: 89.0 ± 13.5 min vs LC: 79.5 ± 12.9 min vs LA: 74.6 ± 12.4 min; P = .39). Plasma ethanol was less after LA than LC (P < .001) and FS (P < .001), with no difference between LC and FS (P = 1.0). There was an inverse relationship between plasma ethanol at 15 min and GE after LA (r = -0.87, P < .01) and a trend for inverse relationships after LC (r = -0.67, P = .07) and FS (r = -0.69, P = .06). The AUC 0-180 min for blood glucose was greater for LA than LC (P < .001), with no difference between LA and FS (P = .40) or LC and FS (P = 1.0).

CONCLUSION

In healthy young subjects, GE of FS, LC and LA beer is comparable and a determinant of the plasma ethanol response.

Acute effects of whey protein, alone and mixed with other macronutrients, on blood pressure and heart rate in older men

BACKGROUND

Caloric supplements are increasingly used by older people, aiming to increase their daily protein intake. These high caloric drinks, rich in glucose and whey-protein in particular, may result in potential harmful decreases in blood pressure (BP). The effect of ingesting whey-protein with glucose and fat on BP is unknown. It has also been assumed that the maximum fall in systolic blood pressure occurs within 2 h of a meal.

METHODS

This study aimed to determine in older men, the effects of whey-protein, alone and mixed with other macronutrients, on systolic (SBP) and diastolic (DBP) blood pressure and heart rate (HR) in older men for 3 h. Thirteen older men (age 75 ± 2yrs; body mass index (BMI) 25.6 ± 0.6 kg/m²) ingested a drink on separate study days: (i) 70 g whey-protein (P₂₈₀)_; (ii) 14 g whey-protein, 28 g carbohydrate, 12.4 g fat (M₂₈₀); (iii) 70 g whey-protein, 28 g carbohydrate, 12.4 g fat (M₅₀₄); or (iv) a non-caloric control drink (C).

RESULTS

SBP decreased after all three nutrient drinks compared to the C, with the greatest reduction after the M₅₀₄ drink (P = 0.008). Maximal decreases in SBP (C: -14 ± 2 mmHg, P₂₈₀: -22 ± 2 mmHg, M₂₈₀: -22 ± 4 mmHg, M₅₀₄: -24 ± 3 mmHg) occurred about 2 h after drink ingestion and this fall was sustained thereafter (120-180 min: P₂₈₀ and M₅₀₄ vs. C P < 0.05). Maximum DBP decreases and HR increases occurred after M₅₀₄, with no differences between the effects of the P₂₈₀ and M₂₈₀ drinks.

CONCLUSIONS

The effects of whey-protein containing drinks to lower BP and increase HR appear to be primarily dependent on their energy content rather than macronutrient composition and may persist for at least 3 h after ingestion,. Pure whey-protein drinks may represent the best approach to maximize protein intake without increasing the potential for deleterious BP falls in older people.

TRIAL REGISTRATION

ACTRN12614000846628 , 14/03/2019.

Acute Administration of the GLP-1 Receptor Agonist Lixisenatide Diminishes Postprandial Insulin Secretion in Healthy Subjects But Not in Type 2 Diabetes, Associated with Slowing of Gastric Emptying

INTRODUCTION

It is uncertain whether lixisenatide has postprandial insulinotropic effects when its effect on slowing gastric emptying is considered, in healthy subjects and type 2 diabetes mellitus (T2DM). We evaluated the effects of single administration of 10 μg sc lixisenatide on glycaemia, insulin secretion and gastric emptying (GE), measured using the 'gold standard' technique of scintigraphy following an oral glucose load (75 g glucose).

METHODS

Fifteen healthy subjects (nine men, six women; age 67.2 ± 2.3 years) and 15 patients with T2DM (nine men, six women; age 61.9 ± 2.3 years) had measurements of GE, plasma glucose, insulin and C-peptide for 180 min after a radiolabeled 75 g glucose drink on two separate days. All subjects received lixisenatide (10 μg sc) or placebo in a randomised, double-blind, crossover fashion 30 min before the drink. Insulin secretory response (ISR) was determined using the C-peptide deconvolution method.

RESULTS

GE was markedly slowed by lixisenatide compared with placebo in both healthy subjects (1.45 ± 0.10 kcal/min for placebo vs. 0.60 ± 0.14 kcal/min for lixisenatide) and diabetes (1.57 ± 0.06 kcal/min for placebo vs. 0.75 ± 0.13 kcal/min for lixisenatide) (both P < 0.001) with no difference between the two groups (P = 0.42). There was a moderate to strong inverse correlation between the early insulin secretory response calculated at 60 min and gastric retention at 60 min with lixisenatide treatment in healthy subjects (r = - 0.8, P = 0.0003) and a trend in type 2 diabetes (r = - 0.4, P = NS), compared with no relationships in the placebo arms (r = - 0.02, P = NS, healthy subjects) and (r = - 0.16, P = NS, type 2 diabetes).

CONCLUSION

The marked slowing of GE of glucose induced by lixisenatide is associated with attenuation in the rise of postprandial glucose in both healthy subjects and diabetes and early insulin secretory response in healthy subjects.

CLINICAL TRIALS REGISTRATION NUMBER

NCT02308254.

Serum bile acid response to oral glucose is attenuated in patients with early type 2 diabetes and correlates with 2-hour plasma glucose in individuals without diabetes

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.

Blood Pressure and Heart Rate Responses following Dietary Protein Intake in Older Men

Postprandial hypotension (PPH) occurs frequently in older people >65 years old. Protein-rich supplements, particularly whey protein (WP), are increasingly used by older people for various health benefits. We have reported that 70 g WP drinks cause significant, and in some cases marked, falls in blood pressure (BP) in older men. The effects of lower, more widely used, doses (~30 g) on systolic (SBP) and diastolic (DBP) blood pressure and heart rate (HR) are not known. In a randomized order, eight older men (age: 72 ± 1 years; body mass index (BMI): 25 ± 1 kg/m2) after overnight fast ingested a drink containing (i) a non-caloric control (~2 kcal), (ii) 30 g of whey protein (120 kcal; ‘WP30’), or (iii) 70 g of whey protein (280 kcal; ‘WP70’). The BP and HR were measured in this pilot study with an automated device before and at 3-min intervals for 180 min following drink ingestion. Drink condition effects were determined by repeated-measures ANOVA. The SBP decreased after both WP drinks compared to the control (p = 0.016), particularly between 120 and 180 min, with no difference in the effects of WP30 and WP70. The SBP decreased by ≥20 mmHg in more than 50% of people after both WP drinks (WP30: 63%; WP70: 75%) compared to 38% after the control. The maximum fall in the SBP occurred during the third hour, with the nadir occurring latest after WP70. The DBP decreased non-significantly by several mmHg more after the WP drinks than after the control. The maximum HR increases occurred during the third hour, with the greatest increase after WP70. The SBP decreased after both WP drinks compared to the control, with the effects most evident between 120 and 180 min. Accordingly, ingestion of even relatively modest protein loads in older men has the potential to cause PPH.

Plasma GLP-1 Response to Oral and Intraduodenal Nutrients in Health and Type 2 Diabetes-Impact on Gastric Emptying

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) inter-individual 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.

The impact of micronutrient supplementation in alcohol-exposed pregnancies on reaction time responses of preschoolers in Ukraine

The potential of micronutrients to ameliorate the impact of prenatal alcohol exposure (PAE) on attentional regulation skills was explored in a randomized clinical trial conducted in Ukraine. Women who differed in prenatal alcohol use were recruited during pregnancy and assigned to one of three groups [No study-provided supplements, Multivitamin/Mineral Supplement (MVM), or MVM plus Choline]. Their offspring were seen in the preschool period and a reaction time task was administered. Participants were asked to press a response button as quickly as possible as 30 stimuli from the same category (animals) were presented consecutively and then followed by six stimuli from a novel category (vehicles). Number correct, mean latency of the response over trials, and variability in the latency were analyzed separately by sex. During the initial animal trials, boys whose mothers received MVM during pregnancy had more correct responses and reduced response latency compared to boys whose mothers had no MVM treatment. During vehicle trials, maternal choline supplementation was associated with increased response speed in males without a PAE history. Females receiving supplements did not show the same benefits from micronutrient supplementation and were more adversely impacted by prenatal alcohol exposure. Relationships between maternal levels of choline, betaine, and dimethylglycine (DMG) and task performance were also assessed. Although no effects were found for choline after adjusting for multiple comparisons, lower baseline DMG level was associated with greater accuracy and shorter latency of responses in the initial animal trials and shorter latency in the vehicle trials in female preschoolers. Level of betaine in Trimester 3 was associated with reduced variability in the latency of male responses during the animal trials. Maternal micronutrient supplementation in pregnancy appears to improve preschool reaction time performance, but the effects varied as a function of sex and PAE exposure status.

Gastrointestinal recovery after surgery: protocol for a systematic review

INTRODUCTION

Gastrointestinal recovery after surgery is of worldwide significance. Postoperative gastrointestinal dysfunction is multifaceted and known to represent a major source of postoperative morbidity, however, its significance to postoperative care across all surgical procedures is unknown. The complexity of postoperative gastrointestinal recovery is poorly defined within gastrointestinal surgery, and even less so outside this field. To inform the clinical care of surgical patients worldwide, this systematic review and meta-analysis will aim to characterise the duration of postoperative gastrointestinal recovery that can be expected across all surgical procedures and determine the associations between factors that may affect this.

METHODS AND ANALYSIS

MEDLINE, Embase, Cochrane Library and CINAHL will be searched for studies reporting the time to first postoperative passage of stool after any surgical procedure. We will screen records, extract data and assess risk of bias in duplicate. Forest plots will be constructed for time to postoperative gastrointestinal recovery, as assessed by various outcome measures. Because of potential heterogeneity, a random-effects model will be used throughout the meta-analysis. Funnel plots will be used to test for publication bias. Meta-regressions will be undertaken where the outcome is the mean time to first postoperative passage of stool, with potential predictors and confounders being patient characteristics, postoperative outcomes and surgical factors.

ETHICS AND DISSEMINATION

This study will not involve human or animal subjects and, thus, does not require ethics approval. The outcomes will be disseminated via publication in peer-reviewed scientific journal(s) and presentations at scientific conferences.

PROSPERO REGISTRATION NUMBER

CRD42021256210.

Potential for Gut Peptide-Based Therapy in Postprandial Hypotension

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

Effects of Standard vs Energy-Dense Formulae on Gastric Retention, Energy Delivery, and Glycemia in Critically Ill Patients

BACKGROUND

Energy-dense formulae are often provided to critically ill patients with enteral feed intolerance with the aim of increasing energy delivery, yet the effect on gastric emptying is unknown. The rate of gastric emptying of a standard compared with an energy-dense formula was quantified in critically ill patients.

METHODS

Mechanically ventilated adults were randomized to receive radiolabeled intragastric infusions of 200 mL standard (1 kcal/mL) or 100 mL energy-dense (2 kcal/mL) enteral formulae on consecutive days in this noninferiority, blinded, crossover trial. The primary outcome was scintigraphic measurement of gastric retention (percentage at 120 minutes). Other measures included area under the curve (AUC) for gastric retention and intestinal energy delivery (calculated from gastric retention of formulae over time), blood glucose (peak and AUC), and intestinal glucose absorption (using 3-O-methyl-D-gluco-pyranose [3-OMG] concentrations). Comparisons were undertaken using paired mixed-effects models. Data presented are mean ± SE.

RESULTS

Eighteen patients were studied (male/female, 14:4; age, 55.2 ± 5.3 years). Gastric retention at 120 minutes was greater with the energy-dense formula (standard, 17.0 ± 5.9 vs energy-dense, 32.5 ± 7.1; difference, 12.7% [90% confidence interval, 0.8%-30.1%]). Energy delivery (AUC₁₂₀ , 13,038 ± 1119 vs 9763 ± 1346 kcal/120 minutes; P = 0.057), glucose control (peak glucose, 10.1 ± 0.3 vs 9.7 ± 0.3 mmol/L, P = 0.362; and glucose AUC₁₂₀ 8.7 ± 0.3 vs 8.5 ± 0.3 mmol/L.120 minutes, P = 0.661), and absorption (3-OMG AUC₁₂₀ , 38.5 ± 4.0 vs 35.7 ± 4.0 mmol/L.120 minutes; P = .508) were not improved with the energy-dense formula.

CONCLUSION

In critical illness, administration of an energy-dense formula does not reduce gastric retention, increase energy delivery to the small intestine, or improve glucose absorption or glucose control; instead, there is a signal for delayed gastric emptying.

Effects of age on blood pressure and heart rate responses to whey protein in younger and older men

BACKGROUND

Postprandial falls in blood pressure (BP) are more common in older compared to younger individuals. The effects of protein compared to carbohydrates and fat on postprandial BP, and the relation to gastric emptying rates, are poorly studied.

OBJECTIVES

To determine the effects of a whey protein compared to a control drink on systolic BP (SBP) and diastolic BP (DBP), and heart rate (HR) in healthy younger and older men, and to relate these effects to gastric emptying.

DESIGN

A pooled analyses of two randomized, double-blind, cross-over studies.

SETTING

Two acute clinical intervention studies with identical study design.

PARTICIPANTS

Nineteen older (age: 74 ± 1 years, body mass index: 26 ± 1 kg/m² ) and 13 younger (23 ± 1 years, 24 ± 1 kg/m² ) healthy men.

INTERVENTION

A 70 g/280 kcal whey-protein or control (water with diet cordial, ~2 kcal) drink (450 ml).

MEASUREMENTS

BP and HR were assessed with an automated device immediately before and at 3-min intervals after drink ingestion (0-180 min). Gastric emptying of the drinks was measured using 3D ultrasonography (0-180 min).

RESULTS

Older versus younger men exhibited a greater fall in SBP (-23 ± 2 vs -15 ± 2 mmHg, p = 0.001) after whey-protein versus control, as BP did not change after the two drinks in younger men (p > 0.05). The nadir in SBP occurred later in the older than younger men (114 ± 11 vs 62 ± 14 min; p < 0.001), with SBP still apparently declining 180 min after whey-protein ingestion in the older men. The magnitude of the rise in HR was greater (p < 0.05) in the younger than older men.

CONCLUSION

Following ingestion of 70 g whey protein, healthy older men exhibited a sustained fall in BP, despite an increase in HR, whereas in younger men there was no change in BP. BP may need to be monitored after high protein meals in older people at risk of postprandial hypotension.

Role of Bile Acids in the Regulation of Food Intake, and Their Dysregulation in Metabolic Disease

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.

Acceleration of Gastric Emptying by Insulin-Induced Hypoglycemia is Dependent on the Degree of Hypoglycemia

CONTEXT

Hypoglycemia is a major barrier to optimal glycemic control in insulin-treated diabetes. Recent guidelines from the American Diabetes Association have subcategorized "non-severe" hypoglycemia into level 1 (<3.9 mmol/L) and 2 (<3 mmol/L) hypoglycemia. Gastric emptying of carbohydrate is a major determinant of postprandial glycemia but its role in hypoglycemia counter-regulation remains underappreciated. "Marked" hypoglycemia (~2.6 mmol/L) accelerates gastric emptying and increases carbohydrate absorption in health and type 1 diabetes, but the impact of "mild" hypoglycemia (3.0-3.9 mmol/L) is unknown.

OBJECTIVE

To determine the effects of 2 levels of hypoglycemia, 2.6 mmol/L ("marked") and 3.6 mmol/L ("mild"), on gastric emptying in health.

DESIGN, SETTING, AND SUBJECTS

Fourteen healthy male participants (mean age: 32.9 ± 8.3 years; body mass index: 24.5 ± 3.4 kg/m2) from the general community underwent measurement of gastric emptying of a radiolabeled solid meal (100 g beef) by scintigraphy over 120 minutes on 3 separate occasions, while blood glucose was maintained at either ~2.6 mmol/L, ~3.6 mmol/L, or ~6 mmol/L in random order from 15 minutes before until 60 minutes after meal ingestion using glucose-insulin clamp. Blood glucose was then maintained at 6 mmol/L from 60 to 120 minutes on all days.

RESULTS

Gastric emptying was accelerated during both mild (P = 0.011) and marked (P = 0.001) hypoglycemia when compared to euglycemia, and was more rapid during marked compared with mild hypoglycemia (P = 0.008). Hypoglycemia-induced gastric emptying acceleration during mild (r = 0.57, P = 0.030) and marked (r = 0.76, P = 0.0014) hypoglycemia was related to gastric emptying during euglycemia.

CONCLUSION

In health, acceleration of gastric emptying by insulin-induced hypoglycemia is dependent on the degree of hypoglycemia and baseline rate of emptying.

Effects of intragastric administration of L-tryptophan on the glycaemic response to a nutrient drink in men with type 2 diabetes - impacts on gastric emptying, glucoregulatory hormones and glucose absorption

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.

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

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