Diabetes mellitus and sperm parameters

Due to the paucity of studies and inconsistencies regarding the impact of diabetes mellitus (DM) on semen quality, this disease is seldom looked for in the infertile patient. Recently, this view has been challenged by findings showing that DM induces subtle molecular changes that are important for sperm quality and function. This brief review shows the main sperm parameters in patients with DM and put forward the mechanisms hypothesized to explain the changes observed in these patients. The data available suggest that DM alters the conventional sperm parameters. In addition, DM causes histological damage of the epididymis with a negative impact on sperm transit. Various mechanisms may explain the sperm damage observed in patients with DM. These include endocrine disorders, neuropathy, and increased oxidative stress. Many authors suggest that DM decreases serum testosterone levels. This is associated with a steroidogenetic defect in Leydig cells. In addition, diabetic neuropathy seems to cause seminal vesicles, bladder, and urethra atony. Furthermore, DM is associated to an increased oxidative stress which damages sperm nuclear and mitochondrial DNA. Finally, spermatogenesis derangement and germ cell apoptosis in type 1 DM may relate to a local autoimmune damage, whereas insulin resistance, obesity, and other related co-morbidities may impair sperm parameters and decrease testosterone serum levels in patients with type 2 DM.