Comparative Effects of Co-Ingesting Whey Protein and Glucose Alone and Combined on Blood Glucose, Plasma Insulin and Glucagon Concentrations in Younger and Older Men

The ingestion of dietary protein with, or before, carbohydrate may be a useful strategy to reduce postprandial hyperglycemia, but its effect in older people, who have an increased predisposition for type 2 diabetes, has not been clarified. Blood glucose, plasma insulin and glucagon concentrations were measured for 180 min following a drink containing either glucose (120 kcal), whey-protein (120 kcal), whey-protein plus glucose (240 kcal) or control (~2 kcal) in healthy younger (n = 10, 29 ± 2 years; 26.1 ± 0.4 kg/m(2)) and older men (n = 10, 78 ± 2 years; 27.3 ± 1.4 kg/m(2)). Mixed model analysis was used. In both age groups the co-ingestion of protein with glucose (i) markedly reduced the increase in blood glucose concentrations following glucose ingestion alone (p < 0.001) and (ii) had a synergistic effect on the increase in insulin concentrations (p = 0.002). Peak insulin concentrations after protein were unaffected by ageing, whereas insulin levels after glucose were lower in older than younger men (p < 0.05) and peak insulin concentrations were higher after glucose than protein in younger (p < 0.001) but not older men. Glucagon concentrations were unaffected by age. We conclude that the ability of whey-protein to reduce carbohydrate-induced postprandial hyperglycemia is retained in older men and that protein supplementation may be a useful strategy in the prevention and management of type 2 diabetes in older people

Comparative effects of glucose and xylose on blood pressure, gastric emptying and incretin hormones in healthy older subjects

Postprandial hypotension is an important disorder for which current management is suboptimal. In healthy older subjects, oral and small-intestinal glucose administration decreases blood pressure (BP), and the magnitude of the reduction is dependent on the rate of glucose entry into the small intestine and, possibly, the release of glucagon-like peptide-1 (GLP-1). There is little information about the effects of other carbohydrates, particularly those poorly absorbed, on BP. The aim of the present study was to compare the effects of drinks containing xylose, glucose or water alone on BP, gastric emptying (GE), incretin hormone secretion, glycaemia and insulinaemia in healthy older subjects. A total of eight healthy older subjects (aged 65–75 years) had simultaneous measurements of BP (DINAMAP), GE (three-dimensional ultrasound), blood glucose, serum insulin, GLP-1 and glucose-dependent insulinotropic peptide (GIP), on three separate occasions, in a double-blind, randomised order. On each day, subjects consumed a 300 ml drink of water, glucose (50 g) or d-xylose (50 g). Glucose (P = 0·02), but not xylose (P = 0·63), was associated with a fall in BP. There was no difference in the GE of glucose and xylose (P = 0·47); both emptied slower than water (P < 0·001). Xylose had minimal effects on blood glucose, serum insulin or serum GIP, but was more potent than glucose in stimulating GLP-1 (P = 0·002). In conclusion, in healthy older subjects, xylose empties from the stomach at the same rate as glucose, but has no effect on BP, possibly because it is a potent stimulus for GLP-1 release. Xylose may be considered as an alternative sweetener to glucose in the management of postprandial hypotension.Lora Vanis, Trygve Hausken, Diana Gentilcore, Rachael S. Rigda, Christopher K. Rayner, Christine Feinle-Bisset, Michael Horowitz and Karen L. Jone

Acute effects of lixisenatide on energy intake in healthy subjects and patients with type 2 diabetes: relationship to gastric emptying and intragastric distribution

International audienceGlucagon-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