Evaluation of Oxidative DNA Damage among Type 2 Diabetes Mellitus Patients and Healthy Individuals in Duhok, Iraq: A Case-control Study

Introduction: The association between oxidative Deoxy Ribonucleic Acid (DNA) damage and diabetes is well established. Increased glucose levels can stimulate free radical production. However, data regarding DNA damage in type 2 Diabetes Mellitus (DM) patients and healthy individuals are controversial and scarce in Iraq.

Aim: To assess the DNA damage among patients with type 2 Diabetes Mellitus (DM) and healthy individuals and to analyse its relationship with oxidative stress biomarkers.

Materials and Methods: This case-control study was conducted at the Duhok Diabetes Center, Duhok, Kurdistan Region, Iraq, from September 2016 to March 2018. In the present study, biomarkers of both oxidative stress and DNA damage including Total Antioxidant Capacity (TAC), Malondialdehyde (MDA) and serum 8-Hydroxy-2-deoxiguanosine (8-OHdG) were measured in 297 patients with type 2 diabetes and 188 healthy individuals. Selection of cases and healthy individuals was done using random sampling technique. Statistical analysis was done using Statistical Package for Social Sciences (SPSS) version 18.0 and a p-value <0.05 was set as a cut off value of statistical significance.

Results: The mean age, sex and Body Mass Index (BMI) were similar between patients and healthy individuals. Significantly higher 8-OHdG and MDA levels (p<0.001 and p<0.010, respectively) together with lower TAC levels (p=0.010) were found in diabetics compared to healthy individuals. In diabetic patients, a positive correlation of 8-OHdG was observed with MDA (r=0.220), and a negative correlation was observed with TAC (r=-0.47). Based on the estimated cut-off point of DNA damage (8-OHdG of 4.0 ng/mL), 84.51% of patients had high levels of DNA damage compared with healthy individuals (28.7%).

Conclusion: Oxidative DNA damage increased in diabetic patients, and was associated with lower antioxidant capacity. Antioxidant supplementation may be an effective public health intervention to reduce DNA damage and oxidative stress.