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

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.