Nuts are rich in unsaturated fatty acids as well as other bioactive constituents. The present study investigated the association between nut consumption and the incidence of type 2 diabetes mellitus (T2DM) in a Middle Eastern population.

The study was conducted within the framework of the Tehran Lipid and Glucose Study (TLGS), in which 1984 participants (920 men and 1064 women) free of DM, aged≥20 years, were followed from phase III (2005–2008) to phase V (2011–2014). Dietary data were obtained from valid and reliable food-frequency questionnaires at baseline. Using multiple logistic regression, odds ratios (ORs) and 95% confidence intervals (CIs) were calculated, with adjustments for age, gender, BMI, serum cholesterol and triglycerides, smoking and energy intake.

Study participants’ means±SD of age and of BMI were 40.1±13.1 years and 27.0±4.8kg/m², respectively. The median±SE of their total daily consumption of nuts was 1.19±0.11 servings. After 6.2±0.7 years of follow-up, 150 cases of T2DM were confirmed. On comparing those who consumed ≥4 servings/week with those who consumed <1 serving/week, the age-/energy-adjusted OR of incident T2DM for total nut consumption was 0.64 (95% CI: 0.36–1.12; P for trend = 0.03). In a fully adjusted model, nut consumption was associated with a lower risk of T2DM, and the ORs (95% CIs) of risk for those consuming 2–3.99 and ≥4 servings/week of nuts were 0.51 (0.26–0.97) and 0.47 (0.25–0.90), respectively, compared with those consuming <1 serving/week (P<0.001 for trend).

Our findings suggest that consuming ≥4 servings/week of nuts reduced the risk of T2DM compared with <1 serving/week.