I was doing some research on this subject this morning, and came across this online news article which I wanted to share with you

Diabetes and obesity are linked to male infertiltiy From Times Online July 9, 2008
Mark Henderson, Science Editor, in Barcelona

The obesity epidemic could be contributing to falling sperm counts and increasing male fertility problems, according to research that shows that both excess weight and diabetes can reduce the quality of a man’s sperm.

Men who are obese or overweight are significantly more likely to produce abnormal sperm and low volumes of semen than those of healthy weight, and those with diabetes — which is commonly triggered by obesity — are more likely to have sperm with genetic damage, two British studies have found.

Read the full story here