The Metabolic Effects of Two Meals with The Same Glycaemic Index But Different Slowly Available Glucose Parameters Determined In Vitro: a Pilot Study

Some foods with a similar Glycaemic Index (GI) are known to have different metabolic impacts in terms of blood glucose and insulin responses. This difference could be explained by the difference in the rapidly and slowly Available Glucose (RAG and SAG) values for the foods determined in vitro. This study was set up to investigate the metabolic impact of two meals with essentially the same GI and macronutrient content but with different SAG values. Twelve healthy male subjects were recruited from the University of Surrey postgraduate student population. RAG and SAG values were measured for each meal based on enzymatic hydrolysis of carbohydrate content. The postprandial glucose, insulin, Triacylglycerol (TAG) and Non-Esterified Fatty Acid (NEFA) responses to high and low SAG meals were determined in two randomised occasions. The incremental Area Under the Curve (iAUC) for glucose and insulin was 106.3 ± 14.46 and 26550 ± 3266, respectively for the low SAG meal. The high SAG meal produced a lower glucose and insulin response with an iAUC of 88.1 ± 10.67 and 23701 ± 3065, respectively; although this difference did not reach statistical significance (p = 0.21 and 0.33 respectively). This work has demonstrated that small differences can occur in the metabolic response for low and high SAG meals in terms of the glucose and insulin levels. This highlights that RAG and SAG values may be an important adjunct to the GI of foods in determining metabolic response.