High HbA_1c 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 HbA_1c level: low HBA_1c  ≤ 5% (31 mmol/mol), moderate HBA_1c 6%-8% (42-64 mmol/mol) and high HBA_1c  ≥ 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 HbA_1c showing the most important deleterious effects. Low gametes' straight-line velocity was observed in high HbA_1c 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 HbA_1c 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.