Impacts of premenopausal type 2 diabetes on female reproductive aging: a scoping review.

Earlier onset of type 2 diabetes could impact the age-related decline of the female reproductive system. Reproductive aging is characterized by decreases in oocyte quality and follicle numbers, and marked by declining fertility, endocrine shifts, and menopause. To better understand how type 2 diabetes might affect this process, we conducted a scoping review of studies that measured reproductive aging-related traits in participants diagnosed with type 2 diabetes before menopause. Systematic searches on MEDLINE, CINAHL, and Web of Science identified studies evaluating type 2 diabetes and traits such as menopause timing, ovarian reserve, and fertility-related outcomes. Exclusion criteria in two-step screening included no control group, post-menopausal diabetes diagnosis, or inclusion of type 1 diabetes in the diabetes group. We identified 16 studies, highlighting a need for more research. Six of seven studies that evaluated menopause timing reported at least one finding that indicated earlier menopause with premenopausal type 2 diabetes, although several associations were confined to specific subgroups and one study reported bidirectional findings depending on age at diabetes diagnosis. Thus, young-onset (before ~40 years) type 2 diabetes may be associated with earlier menopause. Type 2 diabetes conferred increased infertility risks and reduced odds of successful pregnancy outcomes, compared with age-matched controls. Impaired oocyte quality and reduced ovarian reserve may exacerbate these outcomes. Reproductive hormone patterns were not consistent, although some cross-sectional observations suggested an earlier drop in estradiol with type 2 diabetes. Together, these findings demonstrate associations between premenopausal type 2 diabetes and earlier and/or pronounced features of female reproductive decline.