Sex hormone-binding globulin genetic variation: associations with type 2 diabetes mellitus and polycystic ovary syndrome.
Level 5 - mechanism / opinion, no new human data
Narrative review of genetic and epidemiological associations without systematic search methodology or meta-analytic data
What was done
This narrative review summarizes published literature evaluating associations between sex hormone-binding globulin (SHBG) genetic polymorphisms, circulating SHBG concentrations, and the risk of type 2 diabetes mellitus (T2DM) and polycystic ovary syndrome (PCOS).
What was found
The abstract reports no numerical data, odds ratios, or effect sizes. It qualitatively describes that multiple SHBG polymorphisms are associated with alterations in circulating SHBG levels and that low plasma SHBG predicts T2DM development in both sexes. While SHBG-altering polymorphisms associate with T2DM risk, studies in women with PCOS show that although these variants correlate with circulating SHBG levels, they are not consistently associated with PCOS per se.
Why it matters
The findings synthesize evidence suggesting SHBG may play an active role in glucose homeostasis rather than serving solely as a marker of hyperinsulinemia, though its role as a causal candidate gene in PCOS remains unconfirmed.
Limits
The abstract provides no sample sizes, numerical effect estimates, or systematic search criteria. Narrative reviews are subject to selection bias, and associations between SHBG polymorphisms and PCOS phenotype are inconsistent across the literature.
Cited by
- supports High insulin levels in PCOS inhibit hepatic production of sex hormone-binding globulin (SHBG), thereby increasing circulating free androgen and testosterone concentrations.