There are many direct and indirect reasons why diabetes can lead to male infertility. Diabetes is caused when the cells of the pancreas do not make enough insulin, or when the insulin that is made is not received by the target cells. This results in the amount of sugar in the bloodstream to be elevated, which in turn causes many problems throughout the body. Some of these problems are directly related to infertility including diminished sperm quality. When the blood has excess sugar in it, the sperm produced in the testes are more likely to have defects that prevent fertilization. There are also other symptoms of diabetes that can severely impede the ability to reproduce. These include obesity, fatigue, loss of libido and the inability to maintain an erection. Most of these symptoms are a result of too much sugar in the blood, therefore a properly treated diabetic person can overcome most of them, especially with proper nutrition, exercise and weight management.
Research has also shown a direct link between blood sugar levels and sperm quality. In patients with elevated blood sugar levels, the incidence of malformed or dead sperm being found is semen is greatly increased. It was also reported that the total sperm count was significantly reduced in patients with diabetes. Because of the fact that there are less sperm cell in the semen, and a greater number of these are incapable of fertilization, the direct link between diabetes and infertility is obvious.
One of the most often reported symptoms of diabetes is muscle weakness and fatigue. Because either there is a lack of insulin, or the insulin is ineffective, glucose in the bloodstream is not able to enter the cells. Because of this, the cells operate in a permanent state of starvation. Because of this constant fatigue feeling, patients with diabetes are less likely to initiate, and less likely to respond to sexual activity.
Either because of fatigue, or for other reasons, lack of libido is another very common symptom of diabetes. This is primarily thought to be because of the lack of glucose (energy) for certain areas of the brain, the general lack of interest in sex can be attributed to many other symptoms of diabetes including the weakness mentioned before, but also to psychological issues related to obesity, which also is very prevalent in patients with diabetes.
Diabetes also reduces the ability of the individual to maintain an erection, which leads to infertility if the erection is lost before ejaculation occurs. Medications and devices are capable of preventing this problem in some patients, but the other factors related to infertility still exist.