Macronutrient Composition and Food Form Affect Glucose and Insulin Responses in Humans

Abstract

Glycaemic index (GI) is used as an indicator to guide consumers in making healthier food choices. We compared the GI, insulin index (II), and the area under the curve for blood glucose and insulin as glucose (GR) and insulin responses (IR) of a newly developed liquid nutritional formula with one commercially available liquid product with different types of carbohydrates. We then evaluated the glucose and insulin responses of two test foods with comparable energy density and protein percentage but presented in different food forms (liquid vs. solid). Fourteen healthy women participated in the study. GI, II, GR, and IR were assessed after (independent) consumption of two liquid products and a solid breakfast meal. The two liquid foods showed comparable GI, whilst the liquid form appeared to produce lower median GI (25 vs. 54), and II (52 vs. 98) values compared to the solid breakfast (p < 0.02). The median GR and IR for solid breakfast were respectively 44% and 45% higher compared to the liquid product (p < 0.02). Liquid formulas with different carbohydrate qualities produced comparable glucose responses, while foods with comparable energy density and protein percentage but different food form elicited differential effects on GI, II, GR, and IR. Nutrient quality and food form need to be taken into consideration when developing low GI products to manage glycaemic responses.

Keywords: carbohydrate quality; glycaemic and insulin responses; glycaemic index; insulinemic index; nutritional formula; protein quality.

Figure 1

Plasma glucose (a) and insulin (b) after ingestion of two liquid test foods. CP = concept product; CAP = commercially available product; Benjamini Hochberg with corrected levels of significance p = 0.0228; * extreme outliers (median ± 3.0 interquartile range (IQR)); ° inner-fence or minor outliers (median ± 1.5 IQR). Differences in the median of glucose and insulin responses between CAP and CP at 120 min * p < 0.02, based on non-parametric Wilcoxon signed rank test.

Figure 2

Plasma glucose (a) and insulin (b) after ingestion of test foods with different food forms. BFM = breakfast meal; CAP = commercially available product; Benjamini Hochberg with corrected levels of significance p = 0.0228 was applied; * extreme outliers (median ± 3.0 interquartile range (IQR); ° inner-fence or minor outliers (median ± 1.5 IQR); (a) Differences in the median of glucose responses between CAP and BFM at 15 min * p < 0.02, and at 60, 90 and 120 min ** p < 0.005, based on non-parametric Wilcoxon signed rank test; (b) Differences in the median of insulin responses between CAP and BFM at 0, 15, 45, 120 min * p < 0.02, and at 60 and 90 min ** p < 0.005, based on non-parametric Wilcoxon signed rank test.