A two-period randomized crossover study will be conducted to evaluate the effect of nighttime pistachio consumption (i.e., after dinner and before sleep) on fasting blood sugar levels, longer-term blood sugar control, and risk factors for heart disease. This study will also investigate how pistachios affects gut health.

A two-period randomized crossover trial will be conducted. Participants will be randomized to receive each treatment for 12 weeks followed by a minimum 4-week wash-out period. During the pistachio treatment, participants will consume two ounces per day (57 g) of pistachios as an evening snack. During the control phase subjects will be given advice to consume 1-2 exchanges of carbohydrate as an evening snack, which is consistent with usual care. Markers of glycemic control, cardiovascular risk factors and gut health will be assessed at the beginning and the end of each treatment period.

Inclusion Criteria:

• BMI ≥25 and ≤45 kg/m2
• Fasting plasma glucose 100 - 125 mg/dL
• non-Smoking

Exclusion Criteria:

• Diagnosed diabetes or fasting glucose >126 mg/dl
• Systolic blood pressure >160mmHg or diastolic blood pressure >100mmHg)
• Prescribed anti-hypertensive, lipid lowering or glucose lowering drugs
• Established cardiovascular disease, stroke, diabetes, liver, kidney or autoimmune disease or inflammatory conditions
• Use of supplements (psyllium, fish oil, soy lecithin, phytoestrogens) and botanicals and not willing to cease for the duration of the study
• Women who are pregnant, lactating, planning to become pregnant or have given birth in the past year
• Weight loss of >=10% of body weight within the 6 months prior to enrolling in the study
• Smoking or use of any tobacco products
• Allergy/intolerance/sensitive to pistachios
• Consumption of >14 alcoholic drinks/week
• Shift-workers and those who cannot consume a snack in the evening