(P23-066-23) The Effect of Nighttime Pistachio Intake on Fasting Glucose, Cardiometabolic Markers and Diet Quality: A 12 Week Randomized Controlled Trial

Objectives: Nut intake is associated with better glycemic control and lower risk of cardiovascular disease (CVD). It remains unclear if nut intake timing affects glycemic control and CVD risk factors. It is hypothesized that intake of pistachios as a nighttime snack may attenuate early morning endogenous glucose production resulting in lower fasting plasma glucose (FPG). To test this hypothesis, we assessed the effect of consuming 57 g/d of pistachios as a nighttime snack (i.e., after dinner and before sleep) for 12 weeks on markers of glycemic control, vascular health, lipids/lipoproteins and diet quality compared to 1-2 carbohydrate (CHO) exchanges (usual care) in individuals with FPG.

Methods: A single-blind, 2-period, randomized crossover trial was conducted. Participants were educated to consume 57 g/d of dry roasted unsalted pistachios (319 kcal; fat 26 g; CHO 16 g; protein 12 g; saturated fat 3.4 g; fiber 6 g) or 1-2 CHO exchanges (CHO 15-30 g) as a nighttime snack for 12 weeks. Primary (FPG) and secondary outcomes [hemoglobin A1c (HbA1c), insulin, HOMA-IR, lipids/lipoproteins, central and peripheral blood pressure, pulse wave velocity (PWV), and Healthy Eating Index-2015 (HEI-2015)] were measured at the beginning and end of each study period.

Results: 53 participants (37% female, 50.6 ± 10.5 years, 34.9 ± 6 kg/m2, FPG 102 ± 10.6 mg/dL) were randomized. No between-condition difference in FPG was observed (-0.93 mg/dL; 95% CI -2.7, 0.85). HbA1c was lower (-0.019%; 95% CI -0.032, -0.004) following the usual care condition compared to the pistachio condition. No-between condition effects were observed for insulin, HOMA-IR, lipids/lipoproteins, blood pressure, or PWV. The HEI-2015 was higher (4.92 points; 95% CI 0.58, 9.3) following the pistachio condition vs. usual care. This was driven by higher scores for the seafood and plant proteins (2.22; 95% CI 1.4, 3.1), total protein foods (0.51; 95% CI 0.08, 0.95) and refined grains (2.0; 95% CI 0.9, 3.2) components.

Conclusions: In individuals with elevated FPG, intake of 57 g/d of pistachios as a nighttime snack did not improve FPG or other cardiometabolic risk factors compared to the usual care control but increased diet quality. Education to consume 1-2 CHO exchanges as a nighttime snack resulted in a small reduction in HbA1c compared to pistachios.

Funding Sources: American Pistachio Growers