Zinc–Copper ratio and Lipid peroxidation as indicators of glycaemic control in Type 2 diabetes mellitus

Abstract

Objectives: Oxidative stress and trace element imbalance contribute to the pathogenesis of type 2 diabetes mellitus (T2DM). Zinc functions as an antioxidant and insulin cofactor, whereas dysregulated copper may amplify oxidative damage. This study evaluated serum zinc, copper, their ratio (Zn/Cu), and lipid peroxidation markers across glycaemic control categories.

Methods: In this cross-sectional study, 110 adults were classified as normoglycaemic controls (n = 40), well-controlled T2DM (HbA1c ≤ 7.0%, n = 35), and poorly controlled T2DM (HbA1c > 7.0%, n = 35). Serum zinc and copper were measured by flame atomic absorption spectrophotometry; malondialdehyde (MDA) by TBARS assay; and 8-iso-prostaglandin F₂α (8-iso-PGF₂α) by ELISA. Multivariate analysis of covariance adjusted for demographic and clinical covariates, and discriminant analysis identified variables distinguishing glycaemic groups.

Results: Poorly controlled T2DM showed higher copper (21.6 ± 0.54 µmol/L), 8-iso-PGF₂α (205.49 ± 7.23 pg/mL), and MDA (2.30 ± 0.12 µmol/L), with lower zinc (9.17 ± 0.40 µmol/L) and Zn/Cu ratio (0.43 ± 0.30) compared to other groups (p<0.001). Zn/Cu ratio and copper showed the largest effect sizes (partial η² = 0.61 and 0.55, respectively). Zn/Cu ratio correlated negatively with 8-iso-PGF₂α (r = −0.877, p < 0.001) and MDA (r = −0.780, p < 0.001). Discriminant analysis achieved 88.7% accuracy, with Zn/Cu ratio and 8-iso-PGF₂α as key discriminators.

Conclusion: Glycaemic dysregulation in T2DM is linked to increased oxidative stress and zinc–copper imbalance. The Zn/Cu ratio effectively distinguishes glycaemic groups and serves as a cost-effective, adjunctive biomarker to complement HbA1c in risk stratification. These findings are relevant for monitoring metabolic control in resource-constrained settings, pending further validation.