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.