Risk factors of early-onset type 2 diabetes: A systematic review and meta-analysis

Background: Early-onset type 2 diabetes (T2DM), diagnosed before age 40, progresses rapidly and has a higher risk of complications compared to late-onset T2DM. Its global prevalence is rising, but the underlying risk factors are insufficiently understood. Objective: This systematic review and meta-analysis aimed to evaluate risk factors associated with early-onset T2DM to support clinical decision-making and inform preventive strategies. Methods: 37 studies (cohort, case-control, cross-sectional) were identified from PubMed, Web of Science, and Embase up to October 31, 2024. Data were analyzed using STATA 17.0, and pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. Subgroup analyses were performed by region, study type, and sample size. Results: Compared with normoglycemic individuals, early-onset T2DM was strongly associated with family history of diabetes (OR = 4.54, 95%CI: 2.31–8.90), high BMI (OR = 2.87, 95%CI: 2.22–3.80), maternal gestational diabetes (OR = 3.01, 95%CI: 2.44–3.72), and elevated fasting glucose (OR = 8.73, 95%CI: 4.91–16.92). Subgroup and sensitivity analyses confirmed the robustness of these findings despite persistent heterogeneity. In comparisons with late-onset T2DM, family history (OR = 2.90), male sex (OR = 1.57), and BMI (OR = 1.12 per unit) remained significant risk factors. Conclusion: Early-onset T2DM is shaped by familial, metabolic, and lifestyle determinants. Incorporating these factors into early screening and intervention programs, particularly lifestyle modification in young high-risk populations, is essential to reduce disease burden and delay progression.