Dietary insulin index and insulin load in relation to biomarkers of glycemic control, plasma lipids, and inflammation markers

Abstract

Background: Dietary glycemic index and load are widely used to estimate the effect of carbohydrate-containing foods on postprandial blood glucose concentrations and as surrogates for insulin response. The food insulin index (II) directly quantifies the postprandial insulin secretion of a food and takes into account foods with a low or no carbohydrate content.

Objective: We investigated the average dietary II and insulin load (IL) in relation to biomarkers of glycemic control, plasma lipids, and inflammation markers.

Design: In a cross-sectional setting and with the use of data from the Nurses' Health Study and the Health Professionals Follow-Up Study, we measured plasma concentrations of C-peptide, glycated hemoglobin (Hb A(1c)), HDL cholesterol, LDL cholesterol, triglycerides, C-reactive protein (CRP), and interleukin-6 (IL-6) in fasting blood samples of 4002 healthy men and women. The dietary II and IL were assessed from food-frequency questionnaires by using directly analyzed or published food II data.

Results: After multivariate adjustment, participants in the highest quintile of II had 26% higher triglyceride concentrations than did participants in the lowest quintile of II (P for trend < 0.0001). This association was strongest in obese [body mass index (in kg/m(2)) ≥30] participants (difference between highest and lowest quintiles in the II: 72%; P for trend = 0.01). Dietary II was inversely associated with HDL cholesterol in obese participants (difference: -18%; P for trend = 0.03). Similar associations were seen for the IL. Dietary II and IL were not significantly associated with plasma C-peptide, Hb A(1c), LDL cholesterol, CRP, or IL-6.

Conclusion: Dietary II and IL were not associated with fasting biomarkers of glycemic control but may be physiologically relevant to plasma lipids, especially in obese individuals.

Figures

FIGURE 1.

Multivariate-adjusted mean plasma concentrations of fasting HDL according to quintiles of the dietary insulin index in men and women in the following 3 BMI (in kg/m2) categories: <25 (n = 683), 25–29.9 (n = 485), and ≥30 (n = 159). The analysis was adjusted for all covariates mentioned in Table 2 (model 2). P = 0.89 for the interaction between BMI and the dietary insulin index. 1Percentage difference (95% CI) in HDL between highest and lowest quintiles of the insulin index.

FIGURE 2.

Multivariate-adjusted mean plasma concentrations of fasting plasma triglycerides according to quintiles of the dietary insulin index in men and women in the following 3 BMI (in kg/m2) categories: <25 (n = 480), 25–29.9 (n = 396), and ≥30 (n = 118). The analysis was adjusted for all covariates mentioned in Table 2 (model 2). P = 0.27 for the interaction between BMI and the dietary insulin index. 1Percentage difference (95% CI) in triglycerides between highest and lowest quintiles of insulin index.