Background <p>Diet quality scores, such as the Lifelines Diet Score (LLDS) and the Dietary Diversity Score (DDS), can be practical tools for assessing and managing the risks associated with chronic diseases, including gestational diabetes mellitus (GDM). This study aimed to evaluate any possible links between diet quality score, as determined by LLDS, and DDS with GDM.</p> Methods <p>This case-control study was conducted among 274 women, aged 19 to 40 years, with 148 having GDM and 126 without GDM. For each participant, anthropometric values, biochemical tests, and body composition were evaluated by standard protocols and methods. LLDS and DDS calculated dietary quality from a valid and reliable Food Frequency Questionnaire (FFQ) containing 147 items after GDM diagnosis; higher scores indicate higher dietary quality.</p> Results <p>In this study, after adjustment for potential confounding variables (pre-pregnancy weight and BMI, physical activity, smoking status, education level, and life facilities), participants in highest tertiles of LLDS (OR: 0.34; 95%CI: 0.17–0.68, Ptrend = 0.004) and DDS (OR: 0.39; 95%CI: 0.20–0.76, Ptrend = 0.007) had lower odds of GDM compared to women in the lowest tertiles of scores. Similarly, after further adjustment with a family history of diabetes, eclampsia, hypertension, and abortion, showed a significant association between the highest tertiles of LLDS (OR: 0.32; 95%CI: 0.16–0.65, Ptrend = 0.003) and DDS (OR: 0.37; 95%CI: 0.19–0.74, Ptrend = 0.004) with lower odds of GDM.</p> Conclusions <p> The present evidence suggests that individuals with higher adherence to the LLDS and DDS have lower odds of developing GDM.</p>