What you carry at this position in your DNA and what research says about it.
Hormone Binding Globulin: 10/10 evidence, 31 publications.
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Sample genotype (not yours): G/G
Typical Hormone Binding and Higher Diabetes Risk
This genotype is associated with typical levels of sex hormone-binding globulin and higher levels of active free testosterone. However, lower levels of this binding protein are linked to an increased risk of metabolic issues.
What this genotype means: Typical SHBG levels; Higher free testosterone levels; Increased risk of type 2 diabetes.
Sample genotype (not yours): A/A
Highest Hormone Binding with Trade-offs in Active Testosterone
Carrying two copies of the minor allele significantly elevates sex hormone-binding globulin, offering the strongest protection against diabetes. However, this high binding capacity can substantially lower free testosterone levels in men.
What this genotype means: Significantly higher SHBG levels; Lowest risk of type 2 diabetes; Lower free testosterone levels.
Sample genotype (not yours): G/A
Higher Hormone Binding and Lower Diabetes Risk
Carrying one copy of the minor allele increases sex hormone-binding globulin levels, which helps protect against metabolic disorders. This increase moderately reduces the risk of developing type 2 diabetes.
What this genotype means: Moderately higher SHBG levels; Lower risk of type 2 diabetes; Slightly lower free testosterone.
Gene function and biological role
Gene Function: The SHBG gene provides instructions for producing sex hormone-binding globulin, a glycoprotein synthesized primarily by the liver [1]. This protein binds circulating sex steroids, including testosterone and estradiol, regulating their bioavailability in the bloodstream [1] [2]. By controlling the fraction of free, active hormones, SHBG plays a critical role in metabolic health, insulin sensitivity, and reproductive function [2] [3]. Alterations in SHBG levels are strongly linked to metabolic syndrome, cardiovascular health, and the risk of developing type 2 diabetes [3] [4].
Variant Impact: The rs1799941 variant is located in the promoter region of the SHBG gene, where it directly influences gene transcription and protein synthesis [1]. The minor A allele is associated with a significant, dose-dependent increase in circulating SHBG levels [1] [5]. Because SHBG binds sex hormones, carriers of the A allele tend to have higher total testosterone but lower levels of biologically active free testosterone [5] [6]. This shift in hormone binding has downstream effects on metabolic traits, insulin regulation, and male reproductive health [6] [4].
Key Insight: Higher levels of sex hormone-binding globulin act as a natural shield against type 2 diabetes, but they also reduce the amount of active free testosterone available to your tissues.
Location: SHBG. Chromosome 17 · 17p13.1 · 7.6 Mb
Estimated prevalence by population
Global 68.2%; European 54.8%; African 87.2%; East Asian 99.6%; South Asian 82.4%; Americas 71.8%; Ashkenazi 69.2%; Finnish 54.1%; Middle Eastern 64.4%; Amish 51.6%.
Estimated GG genotype frequency.
Global 27.7%; European 38.5%; African 12.3%; East Asian 0.4%; South Asian 16.8%; Americas 25.9%; Ashkenazi 28.0%; Finnish 38.9%; Middle Eastern 31.7%; Amish 40.5%.
Estimated GA genotype frequency.
Global 4.1%; European 6.7%; African 0.4%; East Asian < 0.1%; South Asian 0.9%; Americas 2.3%; Ashkenazi 2.8%; Finnish 7.0%; Middle Eastern 3.9%; Amish 7.9%.
Estimated AA genotype frequency.
Showing effects for G/G genotype
Endocrine & Reproductive
Hormone Levels & Endocrine Regulation
SHBG Levels. Evidence: 8/10. Source: PMID 19064566. Typical Levels.
Free Testosterone. Evidence: 10/10. Source: PMID 24327369. Typical Levels.
Hypogonadism. Evidence: 8/10. Source: PMID 40316537. Typical Risk.
Cardiovascular & Metabolic
Diabetes & Glycemic Traits
Type 2 Diabetes. Evidence: 4/10. Source: PMID 19933169. Increased Risk.
Showing effects for A/A genotype
SHBG Levels. Evidence: 8/10. Source: PMID 19064566. ~24% Higher.
Free Testosterone. Evidence: 10/10. Source: PMID 24327369. Lower Levels.
Hypogonadism. Evidence: 8/10. Source: PMID 40316537. Increased Risk.
Type 2 Diabetes. Evidence: 4/10. Source: PMID 19933169. Lowest Risk.
Showing effects for G/A genotype
SHBG Levels. Evidence: 8/10. Source: PMID 19064566. ~12% Higher.
Free Testosterone. Evidence: 10/10. Source: PMID 24327369. Slightly Lower.
Hypogonadism. Evidence: 8/10. Source: PMID 40316537. Slightly Higher Risk.
Type 2 Diabetes. Evidence: 4/10. Source: PMID 19933169. Reduced Risk.
What this genotype means for the people who carry it
Sample genotype: GG (Homozygous)
Carrying two copies of the common G allele results in standard baseline levels of sex hormone-binding globulin [1]. Because less SHBG is present to bind circulating sex hormones, a larger fraction of testosterone remains free and biologically active [1] [2]. While this supports typical androgen activity, lower SHBG levels are strongly associated with insulin resistance and metabolic syndrome [3]. Large-scale genetic studies demonstrate that individuals with this baseline profile have a higher risk of developing type 2 diabetes over time [4]. This metabolic vulnerability is consistent across diverse populations [3] [4].
Typical SHBG levels; Higher free testosterone levels; Increased risk of type 2 diabetes.
Sample genotype: AA (Homozygous)
Carrying two copies of the A allele results in the highest levels of sex hormone-binding globulin, elevated by about 0.4 standard deviations [1]. This high concentration of SHBG binds a large portion of circulating sex steroids, lowering the amount of free, active testosterone [1] [2]. While this profile provides robust protection against insulin resistance and type 2 diabetes, it presents a distinct physiological trade-off [3] [4]. In men, the marked reduction in free testosterone can increase the risk of hypogonadism and related symptoms [2]. Conversely, in women, higher SHBG can help mitigate symptoms of androgen excess, such as those seen in polycystic ovary syndrome [5].
Significantly higher SHBG levels; Lowest risk of type 2 diabetes; Lower free testosterone levels.
Sample genotype: GA (Heterozygous)
Carrying a single copy of the A allele increases circulating sex hormone-binding globulin levels by approximately 0.2 standard deviations [1]. This moderate elevation in SHBG enhances the body's ability to regulate active sex hormones in the bloodstream [1] [2]. Higher circulating SHBG is highly protective against insulin resistance and metabolic dysfunction [3]. Mendelian randomization studies confirm that this genetically driven increase in SHBG causally reduces the risk of type 2 diabetes [4]. The moderate rise in SHBG typically maintains a healthy balance without severely impacting free hormone availability [2] [3].
Moderately higher SHBG levels; Lower risk of type 2 diabetes; Slightly lower free testosterone.
Variants with shared genetic architecture
rs727428 · SHBG Gene · Chr 17 · SHBG and Metabolism
rs6258 · SHBG Gene · Chr 17 · Hormone Binding Globulin
rs12150660 · SHBG Gene · Chr 17 · Testosterone and Hormone Balance
Relationships of circulating sex hormone-binding globulin with metabolic traits in humans.
SHBG gene polymorphism (rs1799941) associates with metabolic syndrome in children and adolescents.
Polymorphisms in the SHBG gene influence serum SHBG levels in women with polycystic ovary syndrome.
Content updated August 2026.
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