Friday, January 13, 2012

Do not let small study about sperm DNA in diabetic men scare you

All right, it's all over the news today, so men all over the world are wondering if they should father children if they have diabetes. So, let's break this down and interpret it. Scientists have found that sperm from type 1 diabetic men have greater levels of DNA damage than sperm from men who do not have the disease. They warn that such DNA damage might affect a man's fertility.

Researchers from Belfast, Northern Ireland showed that the DNA in the nuclei of the sperm cells had greater levels of fragmentation in diabetic men (52%, versus 32% in non-diabetic men), and that there were more deletions of DNA that would affect the tiny, energy-generating structures in the cells called mitochondria (4 versus 3).

First of all, this is the first study to explore this issue. Second, it involved 27 men with diabetes - not a large number. Not large enough in My Diabetes Information's opinion to get all uptight about. Third, DNA fragments all of the time. It can be a big deal. However, the DNA from a sperm cell is often repaired during conception as it shares DNA from an egg cell. So, there are about 30,000 genes that they can sort through and figure out what this means to men with diabetes. It will be a while.

Dr. Ishola Agbaje, who undertook the research published online this week in the journal Human Reproduction, said, "As far as we know, this is the first report of the quality of DNA in the nucleus and mitochondria of sperm in diabetes. Our study identifies important evidence of increased DNA fragmentation of nuclear DNA and mitochondrial DNA deletions in sperm from diabetic men. These findings cause concern, as they may have implications for fertility."

The truth is that they could have implications for more than just fertility. This is such a new finding from such a small study that it is very early to speculate about what it might mean. What Dr. Agbaje should do is try to find a colleague who can replicate the study with a larger group of patients. The group definitely needs to be composed of at least 30 men with diabetes. It would be even more helpful to involve more than 60 men with diabetes.

Professor Sheena Lewis of Queen's Reproductive Medicine Research Group was one of the researchers involved in the study. Her comments provided a better interpretation of what this might all mean when she said, "Our study shows increased levels of sperm DNA damage in diabetic men. From a clinical perspective this is important, particularly given the overwhelming evidence that sperm DNA damage impairs male fertility and reproductive health. Other studies have already shown that, while the female egg has a limited ability to repair damaged sperm DNA, fragmentation beyond this threshold may result in increased rates of embryonic failure and pregnancy loss. In the context of spontaneous conception, sperm DNA quality has been found to be poorer in couples with a history of miscarriages."

However, Lewis said that it was not possible to say from this current study whether the DNA damage caused by diabetes would have the same effect on men's fertility and the health of future children as DNA damage caused by other factors such as smoking.

"This is just one, relatively small study that highlights a possible concern," she said. "Further studies need to be carried out in order to understand the precise nature of the diabetes-related damage, the causal mechanisms and the clinical significance. Given the global rise in the prevalence of diabetes, it is also vital to examine the reproductive outcomes of pregnancies fathered by diabetic men, and the prevalence of diabetes amongst men attending for infertility treatment."

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