Investigating the effects of mycoprotein and guar gum on postprandial glucose in type 2 diabetes: a double-blind randomised controlled trial.

BACKGROUND: Type 2 diabetes (T2D) is highly prevalent, particularly among south Asian populations, and diet is the first-line strategy to manage postprandial glucose (PG) response. Mycoprotein and guar gum reduce PG in normo-glycaemic people. This study investigates the independent and interactive effects of mycoprotein and guar gum on PG, insulin and appetite responses in white Europeans and south Asians with T2D. METHODS: In this double-blind, crossover, acute, randomised controlled trial, 18 subjects with T2D (10 white European, 8 south Asian) completed six separate visits consuming soy, chicken, and mycoprotein with and without guar gum. Incremental area under the curve (iAUC(0-180 min)) for PG, insulin, and appetite scores, and total AUC(0-180 min) glucagon-like peptide-1 (GLP-1), peptide tyrosine-tyrosine (PYY), as well as ad libitum energy intake and 48h-post-visit energy intake were measured and analysed by linear mixed models with protein, guar gum and ethnicity as fixed effects. RESULTS: We found independent effects of mycoprotein, guar gum and ethnicity on PG iAUC(0-180 min) (mmol/L·min), where mycoprotein reduced PG vs. chicken (-129.84 [95% CI -203.16, -56.51]; p = 0.002), guar gum reduced PG vs. no guar gum (-197.35 [95% CI -254.30, -140.40; p < 0.001], and south Asian had increased PG vs. white Europeans (195.75 [95% CI 66.14, 325.35]; p = 0.005). An interaction between guar gum and ethnicity (p < 0.015) was found for insulin iAUC(0-180 min) (µUI/mL·min), with guar gum lowering insulin responses in south Asian participants (-1909.69 [95% CI -2834.83, -984.511]; p < 0.001). No independent or interactive effects were observed for appetite-related outcomes. CONCLUSION: Mycoprotein and guar gum promote significant independent effects in lowering PG in both white European and south Asians with T2D.