The effect of regular consumption of lupin-containing foods on glycaemic control and blood pressure in people with type 2 diabetes mellitus

Background: Type 2 diabetes mellitus is a metabolic disorder characterized by high glucose and insulin resistance. It is strongly linked to lifestyle, including poor diet and physical inactivity. Lupin is a novel food ingredient, rich in protein and fibre with negligible sugar and starch, which can be incorporated into various foods to reduce glycaemic load. Regular consumption of lupin-enriched foods may be a novel and easily achievable means of reducing overall glycaemic load and improving glycaemic control in diabetes. Objective: To determine whether regular consumption of lupin-enriched foods can improve glycaemic control and lower blood pressure in people with type 2 diabetes mellitus. Design: Fourteen men and 8 women (mean age 58.0 ± 6.6 years and BMI 29.0 ± 3.5 kg m^-2) with type 2 diabetes mellitus were recruited from the general population to take part in a double-blind, randomised, controlled cross-over study. Participants consumed lupin or control foods for breakfast and lunch every day, and for dinner at least 3 days per week during the 8-week treatment periods. Lupin-enriched foods consisted of bread, pasta, Weetbix™ cereal and crumbs, with energy-matched control products. Treatments were completed in random order with an 8-week washout period. All participants monitored their blood glucose levels pre- and post-breakfast and lunch, and their blood pressure in the morning and evening, 3 days per week for the duration of each treatment period. Results: Seventeen participants completed both treatment arms, with all 22 participants (14 males, 8 females) analysed on an intention-to-treat basis. Eight weeks consumption of lupin-enriched food had no significant effect on mean blood glucose levels (mean difference: -0.08 ± 0.06 mmol L^-1, p = 0.214) or post-prandial blood glucose levels (-0.13 ± 0.10 mmol L^-1, p = 0.196). There was no effect on home systolic (-0.4 ± 0.4 mmHg, p = 0.33) or diastolic (0.3 ± 0.3 mmHg, p = 0.321) blood pressure and heart rate (0.5 ± 0.3 bpm, p = 0.152), and no effect on body weight throughout the treatment periods. Conclusion: Regular consumption of lupin-enriched foods had no significant effect on glycaemic control or blood pressure in people with type 2 diabetes mellitus.