OBJECTIVE To examine whether a pistachio-rich diet reduces the prediabetes stage and improves its metabolic risk profile.

RESEARCH DESIGN AND METHODS Prediabetic subjects were recruited to participate in this Spanish randomized clinical trial between 20 September 2011 and 4 February 2013. In a crossover manner, 54 subjects consumed two diets, each for 4 months: a pistachio-supplemented diet (PD) and a control diet (CD). A 2-week washout period separated study periods. Diets were isocaloric and matched for protein, fiber, and saturated fatty acids. A total of 55% of the CD calories came from carbohydrates and 30% from fat, whereas for the PD, these percentages were 50 and 35%, respectively (including 57 g/day of pistachios).

RESULTS Fasting glucose, insulin, and HOMA of insulin resistance decreased significantly after the PD compared with the CD. Other cardiometabolic risk markers such as fibrinogen, oxidized LDL, and platelet factor 4 significantly decreased under the PD compared with the CD (P < 0.05), whereas glucagon-like peptide-1 increased. Interleukin-6 mRNA and resistin gene expression decreased by 9 and 6%, respectively, in lymphocytes after the pistachio intervention (P < 0.05, for PD vs. CD). SLC2A4 expression increased by 69% in CD (P = 0.03, for PD vs. CD). Cellular glucose uptake by lymphocytes decreased by 78.78% during the PD (P = 0.01, PD vs. CD).

CONCLUSIONS Chronic pistachio consumption is emerging as a useful nutritional strategy for the prediabetic state. Data suggest that pistachios have a glucose- and insulin-lowering effect, promote a healthier metabolic profile, and reverse certain metabolic deleterious consequences of prediabetes.