Research
Hormonal
In aging and obese men, elevated sex hormone-binding globulin (SHBG) levels are primarily driven by low growth hormone (GH) and insulin-like growth factor 1 (IGF-1) levels, rather than by hyperinsulinism.
If you are older or obese, your low testosterone may be partly due to low Growth Hormone and IGF-1, not just high insulin. Standard weight loss might not fully restore healthy SHBG levels if GH/IGF-1 remains low.
GoodQualifiesHIGH confidence
our data suggest that GH or IGF-I may be modulators of SHBG levels and that the prevailing low GH/IGF-I levels may explain the age-related increase in the SHBG binding capacity, which occurs despite an increase in insulin levels.
Why this rating
Strong observational data and GH treatment trials in a specific population (n=8), though limited by sample size.
Source
Influence of some biological indexes on sex hormone-binding globulin and androgen levels in aging or obese males.
A. Vermeulen et al. · The Journal of Clinical Endocrinology & Metabolism · 1996
DOI 10.1210/jcem.81.5.8626841
cross_sectional · n=308Cited 442×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
More from this paper
- Total testosterone levels remain relatively stable until approximately age 55 in healthy nonobese men, after which they decline rapidly, while free testosterone declines linearly from a younger age.Strong
- Obesity and high insulin levels are inversely correlated with Total Testosterone and SHBG levels, but weight loss increases SHBG even if insulin remains elevated.Good
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