GlucoTRIG: measuring the impact of high carbohydrate and high fat composite meals on postprandial insulin and triglyceride responses – a randomised controlled crossover trial protocol

Background and objectives: GlucoTRIG is a recently developed novel index to rank the healthiness of composite meals by incorporating postprandial insulin and triglycerides responses. This study aims to examine the impact of high carbohydrate and high fat meals on postprandial insulin and triglycerides responses in humans in order to quantify and evaluate the GlucoTRIG values. Methods: The study is a randomised controlled crossover trial including healthy adult participants (males and females, n=15). The study involves consuming three isocaloric meals (one reference meal and two test meals, Meal 1 and Meal 2) on separate visits of at least one week apart. The three meals comprise of white bread, shredded roast chicken, salad and Thousand Island dressing in different proportions. The reference meal (2001 kJ (477 kcal)) consists of 51.2% carbohydrate, 28.1% fat, 18.2% protein. Meal 1 will be a high-carbohydrate, low-fat meal (2008 kJ (478 kcal)) consisting of 71.4% carbohydrate, 9.4% fat, 17.1% protein. Meal 2 will be a low-carbohydrate, high-fat meal (2002 kJ (477 kcal)) consisting of 34.2% carbohydrate, 44.6% fat, 19.5% protein. At each visit, participants will arrive at the clinic after an overnight fast of at least 12 h. Details of physical activity questionnaire and 24-h food record will be collected. After taking a baseline blood sample at 0 min, participants will be asked to consume the meal within 20 min. Another blood sample will be taken postprandially at 180 min. GlucoTRIG value will be measured as (plasma triglycerides180min x plasma insulin180min)-(plasma triglycerides0min x plasma insulin0min). Study outcomes will be statistically analysed using repeated-measures analysis of variance (ANOVA, SPSS v28, IBM) and Bonferroni post-hoc test for multiple comparisons if applicable, and data presented as mean ± SEM. Results: The GlucoTRIG value of each meal will be compared for differences in insulinaemic and lipaemic responses. Conclusions: The study outcomes will determine if GlucoTRIG is able to detect changes in postprandial insulin and triglycerides after high carbohydrate and high fat composite meals. This project will provide further evidence for GlucoTRIG to be a physiologically relevant index for ranking the healthiness of composite meals for reducing the risk of diet-related metabolic diseases.