Differential effects of low-carbohydrate and low-fat diets on inflammation and endothelial function in diabetes

Objective: To characterize acute (postprandial) and chronic (after a 6-month period of weight loss) effects of a low-carbohydrate vs. a low-fat diet on subclinical markers of cardiovascular disease (CVD) in adults with type 2 diabetes. Design: At baseline and 6 months, measures of C-reactive protein (CRP), interleukin-6 (IL-6), soluble intercellular adhesion molecule (sICAM) and soluble E-selectin were obtained from archived samples (n=51) of participants randomized in a clinical trial comparing a low-carbohydrate and a low-fat diet. In a subset of participants (n=27), postprandial measures of these markers were obtained 3 h after a low-carbohydrate or low-fat liquid meal. Endothelial function was also measured by reactive hyperemic peripheral arterial tonometry during the meal test. Paired t tests and unpaired t tests compared within- and between-group changes. Results: There were no significant differences observed in postprandial measures of inflammation or endothelial function. After 6 months, CRP (mean±S.E.) decreased in the low-fat arm from 4.0±0.77 to 3.0±0.77 (P=.01). In the low-carbohydrate arm, sICAM decreased from 234±22 to 199±23 (P=.001), and soluble E-selectin decreased from 93±10 to 82±10 (P=.05.) A significant correlation between change in high-density lipoprotein and change in soluble E-selectin (r=-0.33, P=.04) and with the change in ICAM (r=-0.43, P=.01) was observed. Conclusions: Low-carbohydrate and low-fat diets both have beneficial effects on CVD markers. There may be different mechanisms through which weight loss with these diets potentially reduces CVD risk.