Postprandial Glucagon-like Peptide-1 Response Research Articles

Influences of Dietary Added Sugar Consumption on Striatal Food-Cue Reactivity and Postprandial GLP-1 Response.

Sugar consumption in the United States exceeds recommendations from the American Heart Association. Overconsumption of sugar is linked to risk for obesity and metabolic disease. Animal studies suggest that high-sugar diets alter functions in brain regions associated with reward processing, including the dorsal and ventral striatum. Human neuroimaging studies have shown that these regions are responsive to food cues, and that the gut-derived satiety hormones, glucagon-like peptide-1 (GLP-1), and peptide YY (PYY), suppress striatal food-cue responsivity. We aimed to determine the associations between dietary added sugar intake, striatal responsivity to food cues, and postprandial GLP-1 and PYY levels. Twenty-two lean volunteers underwent a functional magnetic resonance imaging (fMRI) scan during which they viewed pictures of food and non-food items after a 12-h fast. Before scanning, participants consumed a glucose drink. A subset of 19 participants underwent an additional fMRI session in which they consumed water as a control condition. Blood was sampled for GLP-1, and PYY levels and hunger ratings were assessed before and ~75 min after drink consumption. In-person 24-h dietary recalls were collected from each participant on three to six separate occasions over a 2-month period. Average percent calories from added sugar were calculated using information from 24-h dietary recalls. A region-of-interest analysis was performed to compare the blood oxygen level-dependent (BOLD) response to food vs. non-food cues in the bilateral dorsal striatum (caudate/putamen) and ventral striatum (nucleus accumbens). The relationships between added sugar, striatal responses, and hormone changes after drink consumption were assessed using Spearman’s correlations. We observed a positive correlation between added sugar intake and BOLD response to food cues in the dorsal striatum and a similar trend in the nucleus accumbens after glucose, but not water, consumption. Added sugar intake was negatively associated with GLP-1 response to glucose. Post hoc analysis revealed a negative correlation between GLP-1 response to glucose and BOLD response to food cues in the dorsal striatum. Our findings suggest that habitual added sugar intake is related to increased striatal response to food cues and decreased GLP-1 release following glucose intake, which could contribute to susceptibility to overeating.

GLP-1 response to sequential mixed meals: influence of insulin resistance.

Previous work has shown that potentiation of insulin release is impaired in non-diabetic insulin resistance; we tested the hypothesis that this defect may be related to altered glucagon-like peptide-1 (GLP-1) release. On consecutive days, 82 non-diabetic individuals, classified as insulin sensitive (IS, n=41) or insulin resistant (IR, n=41) by the euglycaemic clamp, were given two sequential mixed meals with standard (75 g, LCD) or double (150 g, HCD) carbohydrate content. Plasma glucose, insulin, C-peptide, non-esterified fatty acids (NEFA) and GLP-1 concentrations were measured; β-cell function (glucose sensitivity and potentiation) was resolved by mathematical modelling. Fasting GLP-1 levels were higher in IR than IS (by 15%, P=0.006), and reciprocally related to insulin sensitivity after adjustment for sex, age, fat mass, fasting glucose or insulin concentrations. Mean postprandial GLP-1 responses were tightly correlated with fasting GLP-1, were higher for the second than the first meal, and higher in IR than IS subjects but only with LCD. In contrast, incremental GLP-1 responses were higher during (i) the second than the first meal, (ii) on HCD than LCD, and (iii) significantly smaller in IR than IS independently of meal and load. Potentiation of insulin release was markedly reduced in IR vs IS across meal and carbohydrate loading. In the whole dataset, incremental GLP-1 was directly related to potentiation, and both were inversely related to mean NEFA concentrations. We conclude that (a) raised GLP-1 tone may be inherently linked with a reduced GLP-1 response and (b) defective post-meal GLP-1 response may be one mechanism for impaired potentiation of insulin release in insulin resistance.

Difference in postprandial GLP-1 response despite similar glucose kinetics after consumption of wheat breads with different particle size in healthy men

PurposeUnderlying mechanisms of the beneficial health effects of low glycemic index starchy foods are not fully elucidated yet. We varied the wheat particle size to obtain fiber-rich breads with a high and low glycemic response and investigated the differences in postprandial glucose kinetics and metabolic response after their consumption.MethodsTen healthy male volunteers participated in a randomized, crossover study, consuming 13C-enriched breads with different structures; a control bread (CB) made from wheat flour combined with wheat bran, and a kernel bread (KB) where 85 % of flour was substituted with broken wheat kernels. The structure of the breads was characterized extensively. The use of stable isotopes enabled calculation of glucose kinetics: rate of appearance of exogenous glucose, endogenous glucose production, and glucose clearance rate. Additionally, postprandial plasma concentrations of glucose, insulin, glucagon, incretins, cholecystokinin, and bile acids were analyzed.ResultsDespite the attempt to obtain a bread with a low glycemic response by replacing flour by broken kernels, the glycemic response and glucose kinetics were quite similar after consumption of CB and KB. Interestingly, the glucagon-like peptide-1 (GLP-1) response was much lower after KB compared to CB (iAUC, P < 0.005). A clear postprandial increase in plasma conjugated bile acids was observed after both meals.ConclusionsSubstitution of 85 % wheat flour by broken kernels in bread did not result in a difference in glucose response and kinetics, but in a pronounced difference in GLP-1 response. Thus, changing the processing conditions of wheat for baking bread can influence the metabolic response beyond glycemia and may therefore influence health.

Equivalent Increases in Circulating GLP-1 Following Jejunal Delivery of Intact and Hydrolysed Casein: Relevance to Satiety Induction Following Bariatric Surgery.

Both Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG) decrease the latency of food delivery to the proximal small intestine. This is implicated in exaggerated post-prandial release of glucagon-like peptide 1 (GLP-1), which provokes early satiety and reductions in food intake. Altered stomach anatomy also creates a deficit in enzymatic pre-processing. The impact of this state effect as a modulator of gut hormone responses remains underexplored. A double-blind cross-over trial study was conducted in 13 healthy subjects assigned to receive in the fasted state and in random order at 1week apart, a direct jejunal infusion of either intact casein or a casein hydrolysate. Downstream effects on GLP-1 release, ratings of hunger and fullness and food and water intake on each study day were recorded when an ad libitum meal was provided 30min after the infusion. Circulating GLP-1 was increased 25min after infusions and peaked to a similar degree at 15min post-meal initiation. The hormone surge had no impact on ratings of hunger and fullness ahead of the ad libitum meal. The kinetic and magnitude of satiation following each infusion was not significantly different. Food and water intake were likewise not differentially impacted by the two infusion types. Protein macronutrient state upon arrival in the small intestine does not in isolation impact upon GLP-1 responses and subsequent onset of satiety. This potentially points to rate of delivery being the dominant factor in exaggerated post-prandial GLP-1 responses in patients post-RYGB and VSG.

Gastric emptying and disease activity in inflammatory bowel disease.

Gastric emptying (GE) is delayed in a subset of patients with inflammatory bowel disease (IBD). We have shown before that altered release of gastrointestinal hormones may contribute to GE disturbances, but overall effects of disease activity remain unclear. Thus, we aimed to evaluate GE in patients with IBD during active disease and following therapy. A total of 20 healthy subjects (HC) and 26 patients with IBD hospitalized because of an acute episode of their disease (Crohn's disease (CD) n = 13, ulcerative colitis (UC) n = 13) underwent a standardized (13) C-octanoic acid GE breath test (baseline test). Plasma glucose, cholecystokinin (CCK), peptide YY (PYY) and glucagon-like peptide-1 (GLP-1) were measured periodically throughout the test. A total of 16 patients underwent a second GE test after 3-4 months of therapy. At baseline, nine patients with IBD had pathologically delayed GE half-time (T½ > 150 min) (P = 0·028 vs. HC). Moreover, T½ was significantly longer in the total group of patients with IBD than in HC (129 ± 12 min vs. 96 ± 7, P = 0·030). Postprandial GLP-1 responses were elevated in IBD (P = 0·002 vs. HC) and correlated with T½ (P = 0·05). Following therapy clinical activity indices and T½ were decreased in IBD (P ≤ 0·01 vs. baseline), and T½ no longer differed from HC (P > 0·5). Moreover, GLP-1 plasma levels decreased significantly (P = 0·031). Higher disease activity in IBD is associated with prolonged GE and increased release of GLP-1. Following effective therapy, GE is accelerated and GLP-1 release decreases significantly. Thus, increased release of GLP-1 from the inflamed mucosa might contribute to GE disturbances in IBD.

Gut Hormone Suppression Increases Food Intake After Esophagectomy With Gastric Conduit Reconstruction.

To characterize the gut hormone profile and determine the effect of satiety gut hormone blockade on food intake in disease-free postesophagectomy patients. Improved oncologic outcomes for esophageal cancer have resulted in increased survivorship and a focus on health-related quality of life. Anorexia and early satiety are common, but putative causative factors, in particular the gut-brain hormonal axis, have not been systematically studied. In a double-blind, placebo-controlled, randomized crossover study, disease-free patients at least 1 year postresection and gastric conduit reconstruction received either 1 mL 0.9% saline or 1 mL (100 μg) octreotide acetate subcutaneously followed by a standardized ad libitum meal on each of two assessments. Fasting and postprandial plasma glucagon-like peptide 1 (GLP-1), peptide YY (PYY), and ghrelin immunoreactivity were measured. Gut hormone responses and calorie intake postsaline versus octreotide were compared between experimental and control groups. Eighteen subjects [esophagectomy (ES), n = 10, 2.4 ± 0.75 years postresection; and unoperated control subjects, n = 8] were studied. ES demonstrated significant weight loss at 3, 6, 12, and 24 months postoperatively (all P < 0.05). Ghrelin levels were similar (P = 0.58) for both groups, but postprandial GLP-1 and PYY responses were significantly (P < 0.001) greater among ES as compared with controls. After octreotide, ad libitum calorie intake increased among ES (1.5 ± 0.2 fold-change, P = 0.02) but not controls (1.1 ± 0.1 fold-change, P = 0.30). ES demonstrated an exaggerated postprandial satiety gut hormone response that was attenuated by octreotide, thus identifying a potential therapeutic target to modulate in the ES patient with early satiety.

The effect of meal composition on postprandial glucagon-like peptide-1 response in overweight/obese participants

Background Glucagon-like peptide-1 (GLP-1) is an incretin hormone secreted in the intestine in response to food intake. GLP-1 may be responsible for nearly 50% of insulin secretion. Postprandial GLP-1 secretion may be impaired in overweight/obese (OW/O) individuals and in patients with type-2 diabetes (T2D). Meals high in protein (HP) or high in monounsaturated fat (HMF) may increase GLP-1 response. However, there are no studies directly comparing HP with HMF meals on postprandial GLP-1 response.

Coffee polyphenol consumption improves postprandial hyperglycemia associated with impaired vascular endothelial function in healthy male adults

Epidemiological studies indicate that habitual coffee consumption lowers the risk of diabetes and cardiovascular diseases. Postprandial hyperglycemia is a direct and independent risk factor for cardiovascular diseases. We previously demonstrated that coffee polyphenol ingestion increased secretion of Glucagon-like peptide 1 (GLP-1), which has been shown to exhibit anti-diabetic and cardiovascular effects. We hypothesized coffee polyphenol consumption may improve postprandial hyperglycemia and vascular endothelial function by increasing GLP-1 release and/or reducing oxidative stress. To examine this hypothesis, we conducted a randomized, acute, crossover, intervention study in healthy male adults, measuring blood parameters and flow-mediated dilation (FMD) after ingestion of a meal with or without coffee polyphenol extract (CPE). Nineteen subjects consumed a test meal with either a placebo- or CPE-containing beverage. Blood biomarkers and FMD were measured at fasting and up to 180 minutes postprandially. The CPE beverage led to a significantly lower peak postprandial increase in blood glucose and diacron-reactive oxygen metabolite, and significantly higher postprandial FMD than the placebo beverage. Postprandial blood GLP-1 increase tended to be higher after ingestion of the CPE beverage, compared with placebo. Subclass analysis revealed that the CPE beverage significantly improved postprandial blood GLP-1 response and reduced blood glucose increase in the subjects with a lower insulinogenic index. Correlation analysis showed postprandial FMD was negatively associated with blood glucose increase after ingestion of the CPE beverage. In conclusion, these results suggest that coffee polyphenol consumption improves postprandial hyperglycemia and vascular endothelial function, which is associated with increased GLP-1 secretion and decreased oxidative stress in healthy humans.

Postprandial glucose, insulin, and glucagon-like peptide-1 responses of different equine breeds adapted to meals containing micronized maize.

The enteroinsular axis is a complex system that includes the release of incretin hormones from the gut to promote the absorption and utilization of glucose after a meal. The insulinogenic effect of incretin hormones such as glucagon-like peptide-1 (GLP-1) remains poorly characterized in the horse. The aim of this study was to compare postprandial glucose, insulin, and GLP-1 responses of different equine breeds adapted to twice-daily meals containing micronized maize. Four Standardbred horses, 4 mixed-breed ponies, and 4 Andalusian cross horses in moderate BCS (5.5 ± 0.2 out of 9) were fed meals at 0800 and 1600 h each day. The meals contained micronized maize (mixed with soaked soybean hulls and lucerne chaff), with the amount of maize gradually increased over 12 wk to reach a final quantity of 1.7 g/kg BW (1.1 g/kg BW starch) in each meal. Animals had ad libitum access to the same hay throughout. After 12 wk of acclimation, serial blood samples were collected from all animals over a 14-h period to measure concentrations of glucose, insulin, and GLP-1, with meals fed immediately after the 0 and 8 h samples. Glucose area under the curve (AUC) values were similar between breed groups (P = 0.41); however, ponies and Andalusian horses exhibited significantly higher insulin AUC values after both meals compared with Standardbred horses (both P < 0.005). Postprandial GLP-1 AUC values were also significantly higher in ponies and Andalusian horses compared with Standardbred horses (breed × time interaction; P < 0.001). Correlation analysis demonstrated a strong positive association between concentrations of insulin and GLP-1 over time (rs = 0.752; P < 0.001). The increased insulin concentrations in ponies and Andalusian horses may partly reflect lower insulin sensitivity but could also be attributed to increased GLP-1 release. Given that hyperinsulinemia is a recognized risk factor for the development of laminitis in domestic equids, this study provides evidence that the enteroinsular axis warrants further investigation.

Postprandial glucagon-like peptide-1 secretion is increased during the progression of glucose intolerance and obesity in high-fat/high-sucrose diet-fed rats.

Glucagon-like peptide-1 (GLP-1) is secreted by distal enteroendocrine cells in response to luminal nutrients, and exerts insulinotropic and anorexigenic effects. Although GLP-1 secretory responses under established obese or diabetic conditions have been studied, it has not been investigated whether or how postprandial GLP-1 responses were affected during the progression of diet-induced obesity. In the present study, a meal tolerance test was performed every week in rats fed a high-fat and high-sucrose (HF/HS) diet to evaluate postprandial glycaemic, insulin and GLP-1 responses. In addition, gastric emptying was assessed by the acetaminophen method. After 8 weeks of HF/HS treatment, portal vein and intestinal mucosa were collected to examine GLP-1 production. Postprandial glucose in response to normal meal ingestion was increased in the HF/HS group within 2 weeks, and its elevation gradually returned close to that of the control group until day 50. Slower postprandial gastric emptying was observed in the HF/HS group on days 6, 13 and 34. Postprandial GLP-1 and insulin responses were increased in the HF/HS group at 7 weeks. Higher portal GLP-1 and insulin levels were observed in the HF/HS group, but mucosal gut hormone mRNA levels were unchanged. These results revealed that the postprandial GLP-1 response to meal ingestion is enhanced during the progression of diet-induced glucose intolerance and obesity in rats. The boosted postprandial GLP-1 secretion by chronic HF/HS diet treatment suggests increased sensitivity to luminal nutrients in the gut, and this may slow the establishment of glucose intolerance and obesity.

Dairy proteins, dairy lipids, and postprandial lipemia in persons with abdominal obesity (DairyHealth): a 12-wk, randomized, parallel-controlled, double-blinded, diet intervention study

Abdominal obesity and exaggerated postprandial lipemia are independent risk factors for cardiovascular disease (CVD) and mortality, and both are affected by dietary behavior. We investigated whether dietary supplementation with whey protein and medium-chain saturated fatty acids (MC-SFAs) improved postprandial lipid metabolism in humans with abdominal obesity. We conducted a 12-wk, randomized, double-blinded, diet intervention study. Sixty-three adults were randomly allocated to one of 4 diets in a 2 × 2 factorial design. Participants consumed 60 g milk protein (whey or casein) and 63 g milk fat (with high or low MC-SFA content) daily. Before and after the intervention, a high-fat meal test was performed. We measured changes from baseline in fasting and postprandial triacylglycerol, apolipoprotein B-48 (apoB-48; reflecting chylomicrons of intestinal origin), free fatty acids (FFAs), insulin, glucose, glucagon, glucagon-like peptide 1 (GLP-1), and gastric inhibitory polypeptide (GIP). Furthermore, changes in the expression of adipose tissue genes involved in lipid metabolism were investigated. Two-factor ANOVA was used to examine the difference between protein types and fatty acid compositions, as well as any interaction between the two. Fifty-two participants completed the study. We found that the postprandial apoB-48 response decreased significantly after whey compared with casein (P = 0.025) independently of fatty acid composition. Furthermore, supplementation with casein resulted in a significant increase in the postprandial GLP-1 response compared with whey (P = 0.003). We found no difference in postprandial triacylglycerol, FFA, insulin, glucose, glucagon, or GIP related to protein type or MC-SFA content. We observed no interaction between milk protein and milk fat on postprandial lipemia. We found that a whey protein supplement decreased the postprandial chylomicron response compared with casein in persons with abdominal obesity, thereby indicating a beneficial impact on CVD risk. This trial was registered at clinicaltrials.gov as NCT01472666.

Temporal changes in glucose homeostasis and incretin hormone response at 1 and 6 months after laparoscopic sleeve gastrectomy

BackgroundBariatric surgery is an effective treatment for morbid obesity. Current literature reports significant improvements in glucose homeostasis after malabsorptive surgery. There is limited evidence on the effects of laparoscopic sleeve gastrectomy (SG) on glucose-insulin homeostasis and postoperative incretin hormone response. The objective of this study was to examine the metabolic effects of SG on temporal changes in insulin and glucose homeostasis, incretin hormones and hepatic insulin clearance in patients with impaired glucose tolerance (IGT) and type 2 diabetes (T2 DM). MethodsA nonrandomized prospective study comprising 22 participants undergoing SG (body mass index [BMI] 50.1 kg/m2, glycated hemoglobin [HbA1c] 53 mmol/mol) and 15 participants undergoing biliopancreatic diversion (BPD) (BMI 62.1 kg/m2, HbA1c 58 mmol/mol). Serial measurements of glucose, insulin, C-peptide, glucagon like peptide-1 (GLP-1) and glucose-dependent insulinotropic hormone (GIP) were performed during oral glucose tolerance testing preoperatively and 1 and 6 months postoperatively. Areas under the curve (AUC) were examined at 30, 60, and 120 minutes. ResultsWithin the SG group, significant improvements were observed respectively at 1 and 6 months in glucose control (HbA1c: −0.9%, −1.3%), measures of insulin sensitivity (fasting insulin: −4.8 mU/L, −8.5 mU/L; fasting C-peptide: −0.6 pmol/L, −1.1 pmol/L; Homeostasis Model Assessment [HOMA-IR]: −0.144, −0.174; HOMA %S:+29.6,+92.4), hepatic insulin clearance (+0.07,+0.13) and postprandial GLP-1 response (AUC0-30 pmol h L−1:+300,+331, AUC0-60:+300,+294, AUC0-120:+316,+295). These results were comparable to the BPD group. ConclusionsSG is associated with significant early improvements in insulin sensitivity and incretin hormone response and results in significant improvements in IGT/T2 DM.

The post-prandial pattern of gut hormones is related to magnitude of weight-loss following gastric bypass surgery: a case-control study

Background. The mechanisms of weight loss after gastric bypass, including the role of gastric hormones, are still not completely understood. While postprandial releases of peptide YY (PYY) and glucagon-like peptide-1 (GLP-1) increase post-surgery and ghrelin usually is reduced, their relationship to the magnitude of the weight loss is still obscure. We explored if differing weight loss after Roux Y gastric bypass (RYGB) in morbidly obese were associated with differing postprandial hormonal release. Methods. We compared patients with large (> 40%) or moderate (< 25%) weight loss three years following RYGP surgery, and an obese control group scheduled for RYGB (six in each group). A 300 kcal mixed meal test was given with blood sampling before and thereafter at 30-min intervals in 180 min. Peak and incremental area under the curve (iAUC) were calculated to characterize postprandial responses. Results. Early postprandial GLP-1 response were significantly higher in the RYGB groups than in the controls, and highest in those with largest weight loss. Postprandial PYY response were also greater for the two RYGB groups vs. controls, but interestingly the controls had higher baseline values. Ghrelin, from similar baseline, was only suppressed in those with the largest weight loss, with close to no reduction in those with modest weight loss or controls. Conclusions. These results support the hypothesis that the magnitude of weight loss after RYGB surgery might be associated with differing patterns of postprandial responses in GLP-1 and ghrelin, but not PYY. Larger studies are warranted.

Prior Exercise and Postprandial Incretin Responses in Lean and Obese Individuals

The incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) help regulate postprandial triacylglycerol (TAG) and insulin concentrations, but the effects of acute aerobic exercise on GLP-1 or GIP responses are unclear. The purpose of this study was to determine whether reductions in postprandial TAG and insulin with exercise are associated with GLP-1 and GIP responses. Thirteen normal-weight (NW) and 13 obese (Ob) individuals participated in two, 4-d trials in random order including an exercise (EX) and a no exercise (NoEX) trial. Diet was controlled during both trials. The EX trial consisted of 1 h of treadmill walking (55%-60% of V˙O2peak) during the evening of day 3 of the trial, 12 h before a 4-h mixed meal test on day 4, during which frequent blood samples were collected to assess postprandial lipemia, glycemia, insulin, C-peptide, GIP, and GLP-1 responses. Insulin secretion was estimated using the insulinogenic index, and insulin clearance was estimated using the ratio of insulin to C-peptide. Postprandial TAG were 29% lower after EX in Ob individuals (P < 0.05) but were not significantly altered in NW individuals (P > 0.05). The drop in postprandial HDL cholesterol was attenuated with EX in Ob individuals (P < 0.05). Insulin responses were 14% lower after EX in Ob individuals (P < 0.05), and this was associated with reduced insulin secretion (P < 0.05), with no change in insulin clearance (P > 0.05). Glucose, C-peptide, GIP, and GLP-1 were not different between trials. A 1-h bout of moderate-intensity aerobic exercise the night before a mixed meal attenuates TAG and insulin responses in Ob but not NW individuals, an effect not associated with altered GLP-1 or GIP responses.

Oral l-Arginine Stimulates GLP-1 Secretion to Improve Glucose Tolerance in Male Mice

Pharmacological and surgical interventions that increase glucagon-like peptide 1 (GLP-1) action are effective to improve glucose homeostasis in type 2 diabetes mellitus. In light of this, nutritional strategies to enhance postprandial GLP-1 secretion, particularly in the context of diet-induced obesity, may provide an alternative therapeutic approach. Importantly, recent evidence suggests the amino acid L-arginine, a well-known insulin secretagogue, can also stimulate release of GLP-1 from isolated rat intestine. Here we tested the hypothesis that oral L-arginine acts as a GLP-1 secretagogue in vivo, to augment postprandial insulin secretion and improve glucose tolerance. To test this, we administered L-arginine or vehicle by oral gavage, immediately prior to an oral glucose tolerance test in lean and diet-induced obese mice. In both lean and obese mice oral L-arginine increased plasma GLP-1 and insulin and substantially improved glucose clearance. To directly assess the contribution of GLP-1 receptor (GLP-1R)-signaling to these improvements, L-arginine was given to Glp1r knockout mice and their wild-type littermates. In this experiment oral l-arginine significantly augmented insulin secretion and improved glucose clearance in WT mice, but not in Glp1r knockout littermates. Taken together these findings identify L-arginine as a GLP-1 secretagogue in vivo and demonstrate that improvement of glucose tolerance by oral L-arginine depends on GLP-1R-signaling. These findings raise the intriguing possibility that L-arginine-based nutritional and/or pharmaceutical therapies may benefit glucose tolerance by improving the postprandial GLP-1 response in obese individuals.

Reduced postprandial GLP‐1 responses in women with gestational diabetes mellitus

We investigated postprandial glucagon-like peptide-1 (GLP-1) responses in pregnant women with and without gestational diabetes mellitus (GDM) and again following delivery when normal glucose tolerance (NGT) was re-established. Eleven women with GDM [plasma glucose (PG) concentration at 120 min after a 75-g oral glucose tolerance test (OGTT): 10.0 ± 0.9 mM (mean ± SD); age: 31 ± 6 years; body mass index (BMI): 31.6 ± 6.4 kg/m(2) ; haemoglobin A1c (HbA1c): 5.6 ± 0.5%] and eight pregnant women with NGT (PG(120 min), OGTT : 5.7 ± 0.7 mM; age: 28 ± 3 years; BMI: 29.7 ± 5.4 kg/m(2) ; HbA1c: 5.4 ± 0.3%) were investigated with a 4-h liquid meal test during third trimester (TT) and 3-4 months postpartum (PP). All patients with GDM re-established NGT following delivery. Pregnancy was associated with low postprandial GLP-1 responses. Patients with GDM exhibited reduced postprandial GLP-1 responses compared to their PP levels [area under curve (AUC): 5.5 ± 1.3 vs. 8.4 ± 3.2 nM × min, p=0.005], but the difference among NGT women (7.3 ± 2.8 vs. 8.8 ± 2.0 nM × min, p=0.066) was not statistically significant. Pregnancy did not influence postprandial responses of the other incretin hormone glucose-dependent insulinotropic polypeptide (GIP) in any of the groups, but GDM patients were characterized by greater postprandial GIP responses during both TT and PP compared to NGT subjects. Pregnancy is associated with reduced postprandial GLP-1 responses (most pronounced in patients with GDM) that normalize after delivery. In contrast, postprandial GIP responses seem unaffected by pregnancy but is increased in GDM patients.

Postprandial gut hormone responses and glucose metabolism in cholecystectomized patients

Preclinical studies suggest that gallbladder emptying, via bile acid-induced activation of the G protein-coupled receptor TGR5 in intestinal L cells, may play a significant role in the secretion of the incretin hormone glucagon-like peptide-1 (GLP-1) and, hence, postprandial glucose homeostasis. We examined the secretion of gut hormones in cholecystectomized subjects to test the hypothesis that gallbladder emptying potentiates postprandial release of GLP-1. Ten cholecystectomized subjects and 10 healthy, age-, gender-, and body mass index-matched control subjects received a standardized fat-rich liquid meal (2,200 kJ). Basal and postprandial plasma concentrations of glucose, insulin, C-peptide, glucagon, GLP-1, glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-2 (GLP-2), cholecystokinin (CCK), and gastrin were measured. Furthermore, gastric emptying and duodenal and serum bile acids were measured. We found similar basal glucose concentrations in the two groups, whereas cholecystectomized subjects had elevated postprandial glucose excursions. Cholecystectomized subjects had reduced postprandial concentrations of duodenal bile acids, but preserved postprandial plasma GLP-1 responses, compared with control subjects. Also, cholecystectomized patients exhibited augmented fasting glucagon. Basal plasma CCK concentrations were lower and peak concentrations were higher in cholecystectomized patients. The concentrations of GIP, GLP-2, and gastrin were similar in the two groups. In conclusion, cholecystectomized subjects had preserved postprandial GLP-1 responses in spite of decreased duodenal bile delivery, suggesting that gallbladder emptying is not a prerequisite for GLP-1 release. Cholecystectomized patients demonstrated a slight deterioration of postprandial glycemic control, probably because of metabolic changes unrelated to incretin secretion.

Changes in gut hormone profile and glucose homeostasis after laparoscopic sleeve gastrectomy

BackgroundChanges in glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) levels after bariatric surgery have been proposed as a mechanism for long-term maintenance of weight loss and improvement in glucose homeostasis postoperatively. The objective of the present study was to assess the changes in GLP-1, PYY, insulin, and glucose levels after laparoscopic sleeve gastrectomy (SG). MethodsTen morbidly obese patients without type 2 diabetes (3 male, 7 female; body mass index [BMI] 47.92±2.06 kg/m2) were evaluated preoperatively and at 6 weeks, 6 months, and 12 months after SG. Total GLP-1, total PYY, insulin, and glucose were measured in fasting state and every 30 minutes after ingestion of 75 g glucose for a total time of 120 minutes. ResultsBMI decreased markedly postoperatively (P<.001). Postprandial total GLP-1 and total PYY responses, measured by the area under the curve (AUC), were significantly increased by the sixth postoperative week compared with preoperative period (P<.001). Fasting insulin levels were markedly decreased postoperatively at all time points (all P<.01). Insulin AUC decreased progressively throughout the first postoperative year (P = .04), whereas glucose AUC decreased significantly at 6 and 12 months postoperatively (both P<.01). Insulin sensitivity measured by the Matsuda index increased progressively postoperatively. First phase insulin secretion remained unchanged. ConclusionPostprandial total GLP-1 and total PYY levels increased significantly at 6 weeks post-SG and remained elevated for at least 1 year. These findings may indicate their involvement in better glucose homeostasis and weight loss maintenance after SG.

Effects of different sweet preloads on incretin hormone secretion, gastric emptying, and postprandial glycemia in healthy humans

Macronutrient "preloads" can stimulate glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), slow gastric emptying, and reduce postprandial glycemic excursions. After sweet preloads, these effects may be signaled by sodium-glucose cotransporter-1 (SGLT1), sweet taste receptors, or both. We determined the effects of 4 sweet preloads on GIP and GLP-1 release, gastric emptying, and postprandial glycemia. Ten healthy subjects were studied on 4 separate occasions each. A preload drink containing 40 g glucose, 40 g tagatose/isomalt mixture (TIM), 40 g 3-O-methylglucose (3OMG; a nonmetabolized substrate of SGLT1), or 60 mg sucralose was consumed 15 min before a (13)C-octanoic acid-labeled mashed potato meal. Blood glucose, plasma total GLP-1 and GIP, serum insulin, and gastric emptying were determined. Both glucose and 3OMG stimulated GLP-1 and GIP release in advance of the meal (each P < 0.05), whereas TIM and sucralose did not. The overall postprandial GLP-1 response was greater after glucose, 3OMG, and TIM than after sucralose (P < 0.05), albeit later after TIM than the other preloads. The blood glucose and insulin responses in the first 30 min after the meal were greatest after glucose (each P < 0.05). Gastric emptying was slower after both 3OMG and TIM than after sucralose (each P < 0.05). In healthy humans, SGLT1 substrates stimulate GLP-1 and GIP and slow gastric emptying, regardless of whether they are metabolized, whereas the artificial sweetener sucralose does not. Poorly absorbed sweet tastants (TIM), which probably expose a greater length of gut to nutrients, result in delayed GLP-1 secretion but not in delayed GIP release. These observations have the potential to optimize the use of preloads for glycemic control. This trial was registered at www.actr.org.au as ACTRN12611000775910.

Comparisons of the effects of 12‐week administration of miglitol and voglibose on the responses of plasma incretins after a mixed meal in Japanese type 2 diabetic patients

To compare the effects of miglitol [an alpha-glucosidase inhibitor (AGI) absorbed in the intestine] and voglibose (an AGI not absorbed) on plasma glucagon-like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP) levels, 26 and 24 Japanese type 2 diabetic patients were randomly assigned to receive miglitol or voglibose, respectively. After 12-week administration of both drugs, during 2-h meal tolerance test, plasma glucose, serum insulin and total GIP were significantly decreased and active GLP-1 was significantly increased. Miglitol group showed a significantly lower total GIP level than voglibose group. Miglitol, but not voglibose, significantly reduced body weight (BW). In all participants, the relative change in BW was positively correlated with that of insulin significantly and of GIP with a weak tendency, but not of GLP-1. In conclusion, both drugs can enhance postprandial GLP-1 responses and reduce GIP responses. The significant BW reduction by miglitol might be attributable to its strong GIP-reducing efficacy.