Effect of Pistachio Intake on Insulin Resistance and Type 2 Diabetes Mellitus

In free-living overweight or obese adult with impaired fasting glucose or impaired glucose tolerance we will compare the effects of a pistachio-rich diet or a Mediterranean Diet on: * Fasting glucose levels, hemoglobin A1c, insulin, C peptide, HOMA IR, advanced glycation end products and soluble receptor of advanced glycation-end products. * Peripheral haemostatic parameters. * Plasma inflammatory markers. * Lymphocyte expression of toll-like receptors, C peptide, resistin and interleukin-6 in peripheral leukocytes. * Lymphocyte glucose transport and expression of glucose transporter 4 in peripheral blood leukocytes. * Platelet function including platelet number, mean platelet volume, platelet factor 4 levels and urinary 11-dehydro-thromboxane B2.