Close relationship between high HbA1c levels and methemoglobin generation in human erythrocytes: The enhancement of oxidative stress in the process.

OBJECTIVE: This study aimed to investigate the effect of diabetic plasma on human red blood cells (RBCs) in order to highlight the amplification mechanisms of oxidative stress (OS) in relation to methemoglobin (metHb) production, a potential bio-indicator that could be related to diabetes disease. RESEARCH DESIGN AND METHODS: Normal RBCs were co-incubated with the diabetic plasma of 24 patients at different HbA1c levels, for 0, 24, and 48 h in order to assess cell turbidity and hemoglobin (Hb) stability. Hb and metHb production were quantified inside and outside RBCs. Malonaldehyde (MDA) level and cell morphology were concomitantly evaluated. RESULTS: The cell turbidity was significantly decreased in the group co-incubated with diabetic plasma at high HbA1c levels (0.074 ± 0.010 AU) compared to the control group (0.446 ± 0.019 AU). A significant decrease in intracellular Hb (0.390 ± 0.075 AU) and its stability (0.600 ± 0.001 AU) were revealed. Also, we found an important increase of metHb levels inside RBCs (0.186 ± 0.017 AU) and in its supernatant (0.086 ± 0.020 AU) after 48 h. Consequently, MDA absorbance increased significantly (0.320 ± 0.040 AU) in RBCs exposed to diabetic plasma with high HbA1c. CONCLUSION: These findings suggest that poor glycemic control in diabetes leads to metHb generation which is the main factor of the OS amplification.

High HbA1c levels affect motility parameters and overexpress oxidative stress of human mature spermatozoa.

The aim of this study is to investigate, by a validated in vitro model, the effect of diabetic plasma on ejaculated human spermatozoa. Plasma of 51 male diabetic patients (mean age 62.28 ± 9.28 years) was selected according to their HbA1c level: low HBA1c  ≤ 5% (31 mmol/mol), moderate HBA1c 6%-8% (42-64 mmol/mol) and high HBA1c  ≥ 10% (86 mmol/mol). The plasma was tested on eighteen normal semen samples by analysing gametes motility using a computer Sperm Class Analyzer® and their corresponding oxidative stress (OS) status using thiobarbituric acid-reactive substances assay. The results indicated that diabetic plasma affected all sperm motility parameters with high HbA1c showing the most important deleterious effects. Low gametes' straight-line velocity was observed in high HbA1c level, mainly after 20 min of co-incubation (8.78 ± 0.47 µm/s). Also, the highest lipid peroxidation (nmoles MDA/108 SPZ) was observed in high HbA1c values (0.92 ± 0.09), higher than those in spermatozoa treated with H2 O2 (0.85 ± 0.04). Conclusively, a direct impact of diabetic plasma on spermatozoa is revealed with overexpression of OS as the underlying mechanism. These findings suggested that it is strongly recommended to control clinically the glycaemic level and OS in diabetic patients for the maintenance of male fertility.