Microvascular and Macrovascular Complications and Their Associated Risk Factors Among Patients with Type 2 Diabetes in Saudi Arabia: A Systematic Review and Meta-Analysis

Background/Objectives: Type 2 diabetes mellitus (T2DM) is a major public health challenge in Saudi Arabia and is associated with substantial morbidity through vascular complications. This systematic review and meta-analysis estimated the pooled prevalence of diabetes-related complications and examined study-level risk factors among Saudi adults with T2DM. Methods: The review followed PRISMA guidance and was registered in PROSPERO (registration number: CRD420251032235). Random-effects models were used, and heterogeneity, risk of bias, small-study effects, subgroup effects, influence, and study-level moderators were assessed. Results: Of 743 records identified, 36 unique, non-overlapping datasets contributed to at least one quantitative synthesis. Study quality was good in 25 studies (69.4%). Pooled prevalences were 24% for retinopathy (95% CI 18–30%; 26 studies), 16% for nephropathy (11–23%; 22 studies), 24% for neuropathy (16–34%; 27 studies), 3% for cerebrovascular stroke (2–6%; 10 studies), 10% for myocardial infarction (MI) and broader coronary heart disease/coronary artery disease (CHD/CAD) (6–15%; 16 studies), 5% for peripheral arterial disease (PAD; 2–11%; 10 studies), and 10% for diabetic foot (4–26%; nine studies). Heterogeneity was extreme (I2 = 93.5–99.3%), and prediction intervals were wide. Excluding influential outliers left pooled estimates essentially similar but reduced τ2. In meta-regression, no moderator was significantly associated with retinopathy, stroke, or diabetic foot prevalence (all p > 0.05). For nephropathy, longer diabetes duration (β = −0.254, 95% CI −0.411 to −0.097, p = 0.005; 52.5% of between-study variance) and female proportion (β = 0.036, 95% CI 0.005 to 0.067, p = 0.026; 18.8%) were significant. For neuropathy, smoking prevalence was significant (β = 0.093, 95% CI 0.001 to 0.185, p = 0.047; 18.8%). For PAD, female proportion was inversely associated with prevalence (β = −0.084, 95% CI −0.147 to −0.021, p = 0.015; 53.2%). Region explained 84.5% of the heterogeneity in MI/CHD/CAD, with lower estimates in Tabuk and Taif, and HbA1c explained 24.5% of the heterogeneity in stroke (p = 0.167). Year of publication explained <10.0% of the heterogeneity in every parsimonious model. Substantial residual heterogeneity remained in all models (residual I2 83.0–99.9%). Individual studies also frequently reported associations of complications with poor glycemic control, longer diabetes duration, hypertension, dyslipidemia, obesity, smoking, and physical inactivity. Conclusions: Diabetes-related complications impose a substantial burden in Saudi adults with T2DM, but estimates vary markedly across populations, clinical settings, and diagnostic definitions. The findings support standardized screening and improved primary research using consistent case definitions; study-level meta-regression findings should be interpreted cautiously.