The effect of protein/fibre drinks on glucose control in people with type 2 diabetes

This trial aims to show that a drink containing protein and a mix of protein and soluble fibre (guar) slows starch hydrolysis and absorption of glucose. The study consists of 2 phases: acute and chronic. Acute study: Participants will attend the research centre at 9am on 5 consecutive weekdays (Mon - Fri), having fasted overnight for 12 hours. On the first test day a continuous glucose monitor will be inserted. It will remain in place for 7 full days and calibrated daily using fingerprick glucoses 4 times/day. On each test day participants will be fed a morning meal consisting of either: (i) 4 slices of white bread with no spreads; (ii) 2 slices (women) or 3 slices (men) of white bread with jam and margarine; (iii) cereal with milk. Tea or coffee with optional sugar and/milk is optional for breakfasts (ii) and (iii). All participants will have each breakfast option twice over the course of 6 consecutive days such that the final meal test will be completed at home unsupervised (food supplied). For each breakfast type (i.e. (i), (ii) or (iii)) on one of the two occasions the breakfast will be preceeded by 150ml of water (control) and on the other occasion preceeded by a 150ml drink containing 20g protein plus 5 g guar (treatment). The drink (control or treatment) will be taken 15 minutes before consuming the breakfast. As such, the 2 occasions for each breakfast type will be conducted in a crossover fashion on two consecutive days with no washout period between the treatment and control occasion for a given type of breakfast. The tests will be performed with 70 volunteers, with randomisation to the order that the treatment or control is given for each type of breakfast meal. Participants are required to keep a log of medication, physical activity and carbohydrate foods consumed during the 7 day period. However, on the last day of wearing the continuous glucose monitor (Sunday) participants can elect not to fill out logs and can eat their normal breakfast. The monitor is removed on the next day (Monday). Participants over the age of 55 will also be given the option to remain in the clinic for 3 hours post-meal on any two days (of the same type of breakfast meal) to have their blood pressure monitored using an ambulatory blood pressure monitor. Chronic study: Following on from the acute study, 140 participants will be randomised to receive the control (no shake mixture provided) or treatment (shake mixture provided) in either the first period (0-3 months) or second period (3-6 months). The treatment group only will be provided with the treatment drink (shake powder) to take home and self-administer with water on a daily basis 15 minutes before breakfast for 6 months. To ensure the shake is effective in the short term in a given participant, participants for the chronic study will first be tested on two consecutive days using breakfast option (i) above and randomised in a crossover fashion on two consecutive days (i.e. no wahout) such that they will receive the treatment (shake) or control (water) 15 minutes prior to the breakfast meal each once on one of the two days. Post-prandial blood glucose levels will once again be measured with a continuous monitor that will be worn for 48 hours. Participants may be enrolled in the acute or chronic study, or both. Participants who have already completed the acute study and shown a good response will not need to undergo the meal test for the chronic study.