Diabetes mellitus and functional sperm characteristics: A meta-analysis of observational studies

Insulin resistance and diabetes mellitus (DM) are well defined causes of female infertility. Animal studies present evidence for decreased sperm quality, but conflicting results have been presented in clinically-orientated studies. We sought to evaluate whether DM affects functional sperm characteristics.

We searched the Medline, Scopus, ClinicalTrials.gov, and Cochrane Central Register of Controlled Trials databases.

DM seems to decrease the seminal volume (MD -0.66ml, 95% CI -1.10, -0.22) and the percentage of motile cells (MD -14.29%, 95% CI -22.76, -5.82) and increase the FSH values (MD 0.47mIU/ml, 95% CI 0.01, 0.93) of men who were screened for infertility. It does not, however, influence the total sperm count (MD 13.16 106 cells, 95% CI -22.75, 49.07), the percentage of normal sperm morphology (-3.06%, 95% CI -6.25, 0.14), or LH (MD 0.65mIU/ml, 95% CI -0.84, 2.13 Supp. Fig. 2) and testosterone values (MD -0.18ng/ml, 95% CI -0.60, 0.24).

Current evidence suggests that the presence of DM seems to influence functional sperm characteristics. Firm results are, however, precluded due to the significant heterogeneity of the included studies. Future prospective studies will clarify whether the DM affects semen quality and IVF outcome.