What you carry at this position in your DNA and what research says about it.
Type 2 Diabetes Risk: 8/10 evidence, 38 publications.
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Sample genotype (not yours): C/C
Higher Risk of Type 2 Diabetes
A genetic profile with two C alleles is associated with a higher risk of developing type 2 diabetes. This genotype is linked to reduced insulin secretion and lower glucose tolerance.
What this genotype means: Increased risk of type 2 diabetes; Reduced insulin secretion; Poorer glucose tolerance.
Sample genotype (not yours): C/T
Moderately Increased Risk of Type 2 Diabetes
An intermediate genetic profile with one C allele and one T allele is associated with a moderately increased risk of type 2 diabetes. This genotype represents an intermediate state for insulin secretion and glucose tolerance.
What this genotype means: Moderately increased risk of type 2 diabetes; Slightly reduced insulin secretion.
Sample genotype (not yours): T/T
Typical Risk of Type 2 Diabetes
A protective genetic profile with two T alleles is associated with a lower risk of type 2 diabetes. This genotype is linked to optimal insulin secretion and better glucose tolerance.
What this genotype means: Lower risk of type 2 diabetes; Optimal insulin secretion; Better glucose tolerance.
Gene function and biological role
Gene Function: The HHEX gene encodes a transcription factor called hematopoietically expressed homeobox, which is essential for the early development of several organs, including the liver, thyroid, and pancreas [1]. In the pancreas, HHEX plays a critical role in the formation and maturation of insulin-producing beta cells [1]. It is also closely situated next to the IDE gene, which encodes insulin-degrading enzyme, a protein responsible for clearing insulin from the bloodstream [2]. Together, this genetic region is one of the most well-established loci influencing insulin secretion and overall glucose homeostasis [3].
Variant Impact: The rs5015480 variant is an intergenic single nucleotide polymorphism located in the chromosomal region between the HHEX and IDE genes. This genetic change does not alter any protein structure directly but instead acts as a regulatory element that influences how these neighboring genes are expressed [1]. Specifically, the variant is thought to alter the activity of enhancers that control HHEX expression in pancreatic islets, thereby affecting pancreatic beta-cell function and insulin secretion [3]. Studies have consistently linked this variant to differences in insulin levels and glucose regulation [4]. Consequently, it is widely studied as a key genetic marker for metabolic health and susceptibility to blood sugar imbalances [5].
Key Insight: This variant sits in an intergenic region between two genes that both regulate insulin, making it a dual-action metabolic regulator.
Location: HHEX. Chromosome 10 · 10q23.33 · 92.7 Mb
Estimated prevalence by population
Global 33.2%; European 34.8%; African 38.9%; East Asian 3.1%; South Asian 19.3%; Americas 27.9%; Ashkenazi 40.9%; Finnish 27.4%; Middle Eastern 44.9%; Amish 21.4%.
Estimated CC genotype frequency.
Global 47.5%; European 48.4%; African 47.0%; East Asian 28.9%; South Asian 49.3%; Americas 49.8%; Ashkenazi 46.1%; Finnish 49.9%; Middle Eastern 44.2%; Amish 49.7%.
Estimated CT genotype frequency.
Global 19.2%; European 16.8%; African 14.2%; East Asian 68.1%; South Asian 31.4%; Americas 22.3%; Ashkenazi 13.0%; Finnish 22.7%; Middle Eastern 10.9%; Amish 28.9%.
Estimated TT genotype frequency.
Showing effects for C/C genotype
Cardiovascular & Metabolic
Diabetes & Glycemic Traits
Type 2 Diabetes. Evidence: 8/10. Source: PMID 17463249. Increased Risk.
Insulin Levels. Evidence: 3/10. Source: PMID 29093273. Lower Levels.
Glucose Tolerance. Evidence: 3/10. Source: PMID 29093273. Reduced Tolerance.
Endocrine & Reproductive
Pregnancy & Birth Complications
Birth Weight. Evidence: 3/10. Source: PMID 19622614. Lower Birth Weight.
Showing effects for C/T genotype
Type 2 Diabetes. Evidence: 8/10. Source: PMID 17463249. Moderate Risk.
Insulin Levels. Evidence: 3/10. Source: PMID 29093273. Typical Levels.
Glucose Tolerance. Evidence: 3/10. Source: PMID 29093273. Typical Tolerance.
Birth Weight. Evidence: 3/10. Source: PMID 19622614. Typical.
Showing effects for T/T genotype
Type 2 Diabetes. Evidence: 8/10. Source: PMID 17463249. Typical Risk.
Insulin Levels. Evidence: 3/10. Source: PMID 29093273. Higher Levels.
Glucose Tolerance. Evidence: 3/10. Source: PMID 29093273. Improved Tolerance.
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
A genetic profile with two C alleles is associated with the highest risk of type 2 diabetes at this locus [1]. Large-scale genetic studies have consistently shown that this genotype increases the odds of developing type 2 diabetes by approximately 15% to 30% compared to those with the protective T/T genotype [2]. The underlying biological mechanism involves reduced expression of the HHEX gene, which impairs the development and function of pancreatic beta cells [3]. As a result, individuals with this genotype tend to secrete less insulin in response to glucose [4]. This can lead to poorer glucose tolerance and higher fasting blood sugar levels over time [5]. Additionally, this genotype has been linked to slightly lower birth weights in newborns, reflecting the role of fetal insulin in prenatal growth [6]. While genetics play a role, lifestyle factors such as diet and exercise remain crucial in managing metabolic risk.
Increased risk of type 2 diabetes; Reduced insulin secretion; Poorer glucose tolerance.
Sample genotype: CT (Heterozygous)
An intermediate genetic profile with one C allele and one T allele is associated with a moderate increase in the risk of developing type 2 diabetes [1]. This intermediate genetic profile is associated with a moderate increase in the risk of developing type 2 diabetes compared to the protective T/T genotype [2]. Research indicates that the single risk allele slightly reduces the efficiency of pancreatic beta cells in secreting insulin [3]. Consequently, glucose tolerance and insulin levels after meals may be slightly lower than in those with the T/T genotype [4]. This genotype is very common across many populations, making metabolic health a shared focus [5]. Maintaining a balanced diet and regular physical activity can effectively offset this moderate genetic predisposition [6]. Monitoring blood sugar levels during routine checkups remains a practical way to track metabolic health.
Moderately increased risk of type 2 diabetes; Slightly reduced insulin secretion.
Sample genotype: TT (Homozygous)
A protective genetic profile with two T alleles is associated with the lowest risk of type 2 diabetes at this locus [1]. Studies show that this genotype supports optimal expression of the HHEX gene, promoting healthy pancreatic beta-cell development and function [2]. Consequently, individuals with this genotype typically exhibit robust insulin secretion in response to glucose [3]. This leads to better glucose tolerance and more efficient blood sugar clearance after meals [4]. The protective effect of this genotype has been replicated across diverse ethnic populations [5]. Additionally, offspring carrying this genotype are less likely to experience the reduced birth weights associated with the risk allele [6]. While this genotype provides a favorable metabolic baseline, maintaining healthy lifestyle habits is still important for long-term wellness.
Lower risk of type 2 diabetes; Optimal insulin secretion; Better glucose tolerance.
Variants with shared genetic architecture
rs1111875 · HHEX Gene · Chr 10 · Type 2 Diabetes Risk
rs7923837 · HHEX Gene · Chr 10 · Type 2 Diabetes Risk
rs2237895 · KCNQ1 Gene · Chr 11 · Type 2 Diabetes Risk
Replication of genome-wide association signals in UK samples reveals risk loci for type 2 diabetes.
Genetic determinants of circulating GIP and GLP-1 concentrations.
Identification of new genetic risk variants for type 2 diabetes.
Twelve type 2 diabetes susceptibility loci identified through large-scale association analysis.
Content updated August 2026.
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