eng Oriental Scientific Publishing Company Biomedical and Pharmacology Journal 0974-6242 2026-03-20 19 1 447 456 10.13005/bpj/3364 70747 article Khalid Mohammad. Abu Khadra 1 Mohamed Izzat. Bataineh 1 Rania Khalid. Abu-Khadra 2 Jumana Saleh 3 Department of Biological Sciences, Yarmouk University, Irbid, Jordan. Faculty of Medicine, Yarmouk University, Irbid, Jordan. Biochemistry Department, Sultan Qaboos University, Muscat, Oman The relationship between obesity, diabetes, and serum oxidative susceptibility remains incompletely understood. This study examined serum oxidizability across metabolically distinct groups to assess how obesity and diabetes interact to influence systemic oxidative potential. Copper-induced serum oxidation kinetics were analysed in four groups: non-diabetic non-obese (NN), non-diabetic obese (NOB), diabetic non-obese (DN), and diabetic obese (DOB). Oxidation was monitored at 245 nm, and total serum oxidizability was quantified as the area under the curve (AUC). Group differences were assessed by one-way ANOVA with post hoc analysis, supported by non-parametric testing where applicable. Correlations and predictors of oxidizability were determined by stepwise multiple regression analysis. Oxidation kinetics demonstrated a stepwise increase in oxidizability across NN → NOB → DN → DOB, indicating additive effects of obesity and diabetes. AUC_total values were significantly higher in NOB, DN, and DOB compared with NN (p < 0.001 for all). The difference between NOB and DOB was significant (p = 0.03), suggesting that diabetes superimposed on obesity further amplifies serum oxidative susceptibility. The largest oxidative gap was observed between NN and DOB (+78.6 AU). Correlation analyses showed that triglycerides (r = 0.27, p < 0.001) and fasting glucose (r = 0.28, p < 0.001) were positively associated with oxidizability, whereas HDL correlated inversely (r = –0.15, p = 0.002). Serum oxidizability rises progressively with metabolic deterioration, reflecting both independent and compounded effects of obesity and diabetes. These findings provide a basis for future longitudinal studies to explore oxidative susceptibility as an early marker and potential therapeutic target in cardiometabolic risk. https://biomedpharmajournal.org/vol19no1/differential-oxidative-susceptibility-between-metabolically-healthy-and-unhealthy-obesity/ AUC kinetics Copper-induced oxidation Obesity Oxidative stress Serum oxidizability Type 2 diabetes