Materials and Methods: In this experimental study, the diabetes was induced using a single intraperitoneal (IP) injection of STZ (50 mg/kg). The rats were assigned to five groups, namely a control group, a diabetic control group, a diabetic group receiving daily carvacrol at a dose of 75 mg/kg, diabetic groups performing treadmill exercise, and a diabetic group performing daily treadmill exercise and receiving carvacrol. After covering the treatment period, all rats were anesthetized and their blood sample were taken. Then the serum levels of oxidative stress markers were measured, the testicles and epididymis were removed, and the sperm parameters were assessed.

Results: The treatment of diabetic rats with carvacrol and treadmill exercise effectively improved testis tissue damage, sperm parameters, glucose, and insulin plasma levels (P = 0.001). In diabetic rats, the level of malondialdehyde (MDA) increased while the activity of superoxide dismutase (SOD) and catalase (CAT) enzymes decreased in the testes tissue (P = 0.001). However, when carvacrol administration (75 mg/kg) was combined with treadmill exercise, these parameters were significantly rectified (P < 0.05).

Conclusion: In sum, administering carvacrol and performing treadmill exercise were effective in improving the sperm parameters and testicular oxidative damage caused by diabetes.