BACKGROUND: We previously reported that a 55g whey protein ‘preload’, taken 30 minutes before a meal, reduced postprandial glycaemia in patients with type 2 diabetes, related to slowing of gastric emptying (GE) and increased secretion of glucagon-like peptide-1 (GLP-1) and insulin We have also shown that guar gum (a viscous polysaccharide that acts as a bulk-forming agent) reduces postprandial glycaemia, due to slowing of GE and small intestinal absorption of glucose.  A smaller dose of whey that could be taken a lesser interval before the meal would be advantageous in terms of cost, reduction in additional energy intake, and compliance.

AIMS To evaluate the effects of a low-dose 20g whey protein preload, formulated with 5g guar, on post-prandial glycaemia and gastric emptying

SUBJECTS AND METHODS:  Fourteen subjects with type 2 diabetes [6 males, 8females; age: 65.8±1.0 years; body mass index: 29.4±1.5 kg/m2; HbA1c: 6.6±0.2% (48.2±2.2mmol/mol); duration of known diabetes: 5.1±1.2 years; 5 managed by diet and 9 managed with metformin only] were each studied on two occasions in a randomised order. On each day, a 150mL preload drink containing either 20g whey plus 5g guar, or similarly flavoured placebo, was consumed 15 minutes before a 13C-octanoic acid-labelled mashed potato meal with 20g glucose (total: 59.1g carbohydrate, 4.3g fat, 5.2g protein; 1,267.5kJ). Blood was sampled frequently for measurement of glucose (glucometer), plasma insulin and total GLP-1 (radioimmunassay). GE was evaluated by breath test.

RESULTS: BLOOD GLUCOSE: Fasting blood glucose concentrations did not differ between the two study days (P=0.68). After the meal, blood glucose concentrations were lower after the whey protein than placebo (treatment effectP=0.024; treatment x time interaction P<0.001), with significant differences at t=30, 60 and 90 minutes. GE was slower after the whey preload as assessed by gastric half-emptying time (p=0.032). There was no difference in plasma insulin or GLP-1 concentrations between whey preload and placebo.

CONCLUSIONS: A low-dose whey protein preload can slow gastric emptying
and improve postprandial glycaemic excursions in patients with type 2 diabetes who have relatively good glycaemic control. This approach represents a promising nutritional strategy to optimize postprandial glycaemia in type 2 diabetes.