Influence of the angiotensin-converting enzyme insertion/deletion polymorphism and oxidative stress on type 2 diabetic retinopathy

Abstract

Objective: This study aimed to investigate the association of the angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism with glycaemic parameters and reactive oxygen species (ROS) levels in patients with type 2 diabetic retinopathy.

Methods: A case-control study was conducted involving 32 patients clinically diagnosed with diabetic retinopathy and 31 age-matched healthy controls. ACE I/D genotyping was performed using the polymerase chain reaction. Glycaemic markers, including fasting blood glucose, HbA1c, insulin, HOMA-IR, and HOMA-IS, were measured alongside ROS levels. Statistical analyses included t-tests, chi-square tests, and correlation matrices to evaluate associations between variables.

Results: Patients with diabetic retinopathy demonstrated significantly elevated glycaemic parameters compared to controls: fasting blood glucose (187.47±77.58 vs 86.68±17.86 mg/dL, p<0.001), HbA1c (8.34±2.13 vs 5.15±0.49%, p<0.001), insulin (23.12±10.0 vs 6.08±1.51 μIU/mL, p<0.001), and HOMA-IR (12.81±11.24 vs 1.29±0.37, p<0.001). ROS concentrations were markedly higher in the patient group (34.51±21.36 vs 15.36±6.74, p<0.001). ACE genotyping revealed only DD and DI genotypes across both groups, with the II genotype absent in this cohort. No significant association was detected between ACE genotype distribution and diabetic retinopathy susceptibility (p=0.701). Sex-stratified analysis showed no significant differences in genotype distribution (p=0.819) or allele frequency (p=0.528). Comparison of biochemical and oxidative stress markers between DD and DI genotypes revealed no significant genotype-dependent variations.

Conclusions: The ACE I/D polymorphism does not appear to contribute to diabetic retinopathy susceptibility in this Iraqi cohort. Despite significant metabolic dysregulation and elevated oxidative stress among patients, this genetic variant demonstrated no direct influence on disease pathogenesis.