Association between the lifelines diet score and the odds of prediabetes and type 2 diabetes mellitus in Iranian adults: a cross-sectional study

The Lifelines Diet Score (LLDS) is a useful dietary index that assesses overall adherence to a healthy dietary pattern. To date, no studies have examined its association with type 2 diabetes mellitus (T2DM) in the adult Iranian population. This study aimed to investigate the association between adherence to the LLDS and the odds of prediabetes and T2DM in a large sample of Iranian adults. This cross-sectional study included 4,873 participants aged 35–65 years from the Mashhad Atherosclerotic Heart Disease and Stroke Cohort Study (MASHAD). Dietary intake was assessed using a validated 65-item food frequency questionnaire. The LLDS was calculated based on 12 food groups, and participants were categorized into tertiles based on their LLDS. Anthropometric, biochemical, and lifestyle data were collected. Multivariable logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for diabetes and prediabetes across LLDS tertiles after adjustment for age, sex, marital status, education, smoking, physical activity, and body mass index. Among 4,873 participants, 707 had diabetes and 434 had prediabetes. Higher LLDS was associated with healthier anthropometric and biochemical profiles. In the fully adjusted model (model 3), participants in the highest LLDS tertile had 33% lower odds of T2DM (OR = 0.67, 95% CI: 0.53–0.83, P-trend < 0.001) and 30% lower odds of prediabetes (OR = 0.70, 95% CI: 0.53–0.91, P-trend = 0.009) compared to the lowest tertile. Greater adherence to a high-quality diet, as reflected in the LLDS, was inversely associated with the odds of T2DM and prediabetes in Iranian adults. These findings suggest that dietary improvements may be associated with lower odds of glycemic disorders in this population.