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

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

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

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 ± 0.9kg/m2, HbA1c 6.3 ± 0.2%) consumed a mashed potato meal comprising 65g powdered potato, 20g glucose, 250ml water, an egg yolk labelled with 100μL 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 Kel=0.60 (the elimination constant) best approximated the scintigraphic gastric emptying curve. There was a relationship between the T50 calculated with scintigraphy and by both Wagner-Nelson Kel=0.60 (r2=0.45, P<0.05) and conventional analysis (r²=0.44, P<0.05). There was no significant difference in the 50% gastric emptying time for scintigraphy (68.5 ± 4.8 min) and Wagner-Nelson Kel=0.60 (71.3 ± 4.5 min), however, the 50% gastric emptying time calculated by conventional analysis was much greater at 164.7 ± 6.0 min (P<0.001). Conclusion: In type 2 diabetes, gastric emptying of a mashed potato meal measured using a ¹³C-octanoic acid breath test analysed with Wagner-Nelson Kel=0.60 closely reflects measurements obtained with scintigraphy, whereas, in absolute terms, the conventional breath test analysis does not.