Chapter 30 – Influence of Male Hyperinsulinemia on IVF Outcome

The investigation of the role of insulin in male infertility is of clinical importance as insulin levels have an impact on the reproductive ability of men. Glucose and insulin fluctuations lead to important molecular alterations that may have a negative effect on spermatogenesis. The maintenance of spermatogenesis depends on glucose metabolism and the control of glucose levels, and glucose metabolism in the germ cells of the testes is pivotal. The absence of insulin in men affected by insulin-dependent diabetes has a negative effect on endocrine control and spermatogenesis. Little is known about the effect of raised insulin levels on sperm quality and male fertility. A higher number of good quality blastocysts and pregnancies were obtained in an in vitro fertilization (IVF) program from donors with normal fasting insulin levels, suggesting an association between hyperinsulinemia and IVF outcome. Raised insulin levels had a negative effect on chromatin packaging as measured with the CMA3 test. Hyperinsulinemic males showed a higher percentage of sperm with poor DNA chromatin packaging and DNA fragmentation. Improvement in sperm morphology and CMA3 levels were demonstrated in infertile hyperinsulinemic men after treatment with metformin and supplements. Infertile males with hyperinsulinemia should be advised to take their body mass index, diet, and lifestyle into consideration as healthy adaptations may enhance their IVF outcome.