London, July 9 (IANS) Researchers from Queen’s University have shown that excess sugar in the blood directly affects sperm quality and consequently male fertility, overturning popular perceptions. The increasing number of youths being diagnosed with diabetes has coincided with global concerns over male fertility, pointed out Con Mallidis of Queen’s in Belfast, who led the research.

“But this is not simply a coincidence. We have shown for the first time that diabetes adversely influences male fertility at a molecular level,” he added.

Scientists studied semen samples from diabetic men receiving insulin therapy. On routine microscopic examination, the semen samples appeared normal, except for slight decrease in volume.

“But when we looked for DNA damage, we saw a very different picture,” said Mallidis, adding that this is not part of a routine semen analysis.

“Sperm RNA was significantly altered, and many of the changes we observed are in RNA transcripts involved in DNA repair. And comparison with a database of men of proven fertility confirmed our findings.

“Diabetics have a significant decrease in their ability to repair sperm DNA, and once this is damaged it cannot be restored.”

Transcription is the synthesis of RNA under the direction of DNA, and is the first step towards gene expression, where the information from the gene becomes a product such as a protein translating the genetic information into a cellular function.

Errors in transcription cause errors in the function of the gene. “We were particularly interested to see a 14-fold decrease in the expression of a protein called ornithine decarboxylase, responsible for the production of compounds responsible for cell growth that help stabilise the structure of DNA.”

“We also found that spermatogenesis 20, a factor unique to the testis and whose function remains unknown, was greatly increased. Taken together, these factors indicate clearly that having diabetes has a direct influence on the health of semen.”

These findings were presented Wednesday at the 24th annual conference of the European Society of Human Reproduction and Embryology.