Differential effects of two isoenergetic meals rich in saturated or monounsaturated fat on endothelial function in subjects with type 2 diabetes

OBJECTIVE—To examine the acute effects of consumption of monounsaturated (MUFAs) and saturated fatty acids (SAFAs) on endothelial function in subjects with type 2 diabetes.RESEARCH DESIGN AND METHODS—A total of 33 participants were examined after consumption of two different isocaloric meals: one rich in MUFA and one rich in SAFA, in the form of extra-virgin olive oil and butter, respectively. Endothelial function was assessed by determination of flow-mediated dilatation (FMD).RESULTS—FMD did not change significantly after the MUFA-rich meal but declined after the SAFA-rich meal. The FMD during the experiment, expressed as incremental area under the curve, increased after the MUFA-rich meal by 5.2 ± 2.5% and decreased after the SAFA-rich meal by 16.7 ± 6.0% (Δ = −11.5 ± 6.4%; P = 0.008).CONCLUSIONS—Consumption of an SAFA-rich meal is harmful for the endothelium, while a MUFA-rich meal does not impair endothelial function in subjects with type 2 diabetes.Endothelial dysfunction occurs early in the course of type 2 diabetes and contributes to the development of macrovascular complications of the disease (1,2). Consumption of saturated fatty acids (SAFAs) impairs endothelial function for up to 6 h postmeal (3), whereas data on the effect of monounsaturated fatty acids (MUFAs) on endothelial function in subjects with type 2 diabetes are limited. According to recent nutritional recommendations, individuals with diabetes should substitute SAFA for MUFA in their diet (4), and the predominant source of MUFA in many countries is oleic acid contained in olive oil. However, the effect of consumption of olive oil on endothelial function in subjects with type 2 diabetes is not known. We tested the hypothesis that consumption of MUFA in the form of olive oil exerts a better effect on endothelial function in subjects with type 2 diabetes than that associated with consumption of butter. Because endothelial function is affected by high blood glucose, lipid and insulin concentrations, and increased oxidative stress (2), we measured these parameters during the study.