The DNA quality of sperm is connected to decreased embryo quality © Shutterstock

In recent years, scientists the world over have been working on finding a link between juvenile diabetes and male fertility, particularly as the number of young diabetics grows. Dr Mallidis pointed out that there is no coincidence between the increase in diabetics and global concerns over this metabolic disorder. 'We have shown for the first time that diabetes adversely influences male fertility at a molecular level,' he said.

Samples of semen were taken from diabetic men who were undergoing insulin treatment. At first, a routine microscopic examination showed that the semen samples were normal. The only difference was that the volume of semen was slightly decreased. However, a second look gave the research team new information: the DNA was damaged. Dr Mallidis explained that while checking DNA is not part of a routine semen analysis, the team discovered a significant change in the RNA of sperm.

'Many of the changes observed are in RNA transcripts involved in DNA repair,' the University researcher said. 'And comparison with a database of men of proven fertility confirmed our findings,' he added. 'Diabetics have a significant decrease in their ability to repair sperm DNA, and once this is damaged it cannot be restored.'

Transcription is the process through which a base sequence of messenger RNA is synthesised on a template of complementary DNA. The information from the gene, according to experts, becomes a product — for example, a protein translating the genetic information into a cellular function. With errors present in transcription come errors in gene function.

'We were particularly interested to see a 14-fold decrease in the expression of a protein called ornithine decarboxylase, which is responsible for the production of spermine and spermidine, compounds responsible for cell growth that help stabilise the structure of DNA,' Dr Mallidis commented.

The research team also discovered that spermatogenesis 20, 'a factor unique to the testis and whose function remains unknown', increased significantly, he said. 'Taken together, these factors indicate clearly that having diabetes has a direct influence on the health of semen,' Dr Mallidis explained.

Scientists have linked the DNA quality of sperm with decreased embryo quality, low embryo implantation rates, a number of childhood diseases and higher miscarriage rates. While the causes for the sperm DNA fragmentation are not clear, Dr Mallidis said his team found a class of compounds, the so-called advanced glycation end products (AGEs), in the male reproductive tract that are 'formed because of glycation (i.e. extra sugar) and accumulate during normal ageing', he said.

Dr Mallidis said, 'They are dependent on lifestyle and in many diabetic complications are centrally implicated in DNA damage. We believe that they play a similar role in the male reproductive system.'

The next research step for Dr Mallidis and his team is to determine the role AGEs play in DNA damage.