Men with diabetes may be suffering a somewhat unexpected side effect of the blood sugar and insuling resistence disorder.  Men with diabetes may have damaged sperm, which can render them infertile and unable to reproduce with their female partners in some cases. 

The studies on men’s sperm involved healthy men without diabetes and men with type-1 diabetes and came to the conclusion that not only do men with diabetes produce less semen during ejaculation, but also tend to have damaged sperm at a higher, statistically significant rate than men without this type of diabetes. 

Damaged sperm can not only affect male fertility, but it has also been linked to couples that have miscarriages althought the exact cause for this is not known currently.  The study was only on men with type-1 diabetes which is mostly hereditary in nature, and has not yet been done that I know of, on men with type-2 diabetes, which is fairly common these days unfortunately.  Type-2 diabetes is on-set, meaning it’s not genetic but rather is usually caused by lifestyle choices such as obesity, bad diet habits and lack of physical activity.