Moderate Coffee Consumption and Its Protective Role Against Type 2 Diabetes in Men: A Meta-analysis Study

Background and Objective: Coffee consumption has been widely studied for its potential effects on the risk of type 2 diabetes mellitus (T2DM), with mixed results across studies. This study aims to evaluate the association between daily coffee intake and the risk of developing T2DM in men. Methods: A comprehensive search of the Scopus, PubMed, and Web of Science databases was conducted up to October 13, 2024, to identify cohort studies that examined coffee consumption and T2DM risk among men. Studies were selected based on predefined inclusion criteria, and data on relative risk (RR), odds ratio (OR), or hazard ratio (HR) were extracted. The quality of studies was assessed using the Newcastle-Ottawa Scale. Statistical analyses were performed using random effects models for dose-response relationships, and potential nonlinear associations were explored using restricted cubic splines. Publication bias was assessed using Egger’s and Begg’s tests. Results: A total of 12 studies with 266,183 participants were included. The dose-response meta-analysis revealed a linear decrease in T2DM risk with each additional cup of daily coffee, with a pooled RR of 0.91 (95% CI: 0.89–0.93) for the linear term. The quadratic term (dose squared) showed a modest upward adjustment in effect, suggesting a nonlinear relationship, with an RR of 1.004 (95% CI: 1.002–1.006). There was no significant publication bias (Egger's test p = 0.39, Begg’s test p = 0.38). Conclusions: This study demonstrated that while moderate coffee consumption provides significant benefits, higher intake does not yield additional advantages, helping to refine dietary recommendations. The identified nonlinear relationship underscores the need for further research to establish the upper limits of coffee intake and its long-term metabolic impact.