What you carry at this position in your DNA and what research says about it.
Type 2 Diabetes Risk: 10/10 evidence, 42 publications.
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Sample genotype (not yours): C/C
Higher Risk of Type 2 Diabetes
Presence of two C alleles is associated with a higher risk of developing type 2 diabetes and elevated fasting blood glucose levels. However, this genetic profile is also linked to a slightly lower average body mass index.
What this genotype means: Higher risk of type 2 diabetes; Elevated fasting blood glucose levels; Slightly lower average body mass index.
Sample genotype (not yours): C/T
Slightly Higher Risk of Type 2 Diabetes
Presence of one C allele is associated with a moderately increased risk of type 2 diabetes and slightly higher blood sugar levels. The impact on body mass index is generally typical.
What this genotype means: Moderately increased risk of type 2 diabetes; Slightly elevated fasting blood glucose levels.
Sample genotype (not yours): T/T
Typical Risk of Type 2 Diabetes
Presence of two T alleles is associated with a typical, lower risk of type 2 diabetes and lower fasting blood glucose levels. However, it is also linked to a slightly higher average body mass index.
What this genotype means: Typical, lower risk of type 2 diabetes; Lower fasting blood glucose levels; Slightly higher average body mass index.
Gene function and biological role
Gene Function: KCNJ11 encodes the Kir6.2 subunit of the ATP-sensitive potassium channel in pancreatic beta-cells [1]. This channel plays a critical role in coupling glucose metabolism to insulin secretion [1]. When blood glucose levels rise, ATP increases, closing the channel and triggering insulin release [2]. Common variants in this gene can alter channel activity, affecting how efficiently the body secretes insulin in response to sugar [2].
Variant Impact: The rs5215 variant is a missense mutation in the KCNJ11 gene that changes the amino acid at position 337 from valine to isoleucine [2]. This alteration is in high linkage disequilibrium with other key functional variants in the gene, such as rs5219 [3]. The change influences the sensitivity of the potassium channel, thereby impacting insulin secretion and blood glucose regulation [1]. Large-scale genetic studies have consistently linked this variant to susceptibility to type 2 diabetes [4].
Key Insight: This variant is almost perfectly linked to another famous diabetes-associated variant, rs5219, meaning they are almost always inherited together.
Location: KCNJ11. Chromosome 11 · 11p15.1 · 17.4 Mb
Estimated prevalence by population
Global 10.2%; European 13.2%; African 0.8%; East Asian 12.4%; South Asian 14.1%; Americas 10.9%; Ashkenazi 12.6%; Finnish 22.0%; Middle Eastern 8.8%; Amish 26.8%.
Estimated CC genotype frequency.
Global 38.0%; European 46.3%; African 16.3%; East Asian 45.7%; South Asian 46.9%; Americas 44.2%; Ashkenazi 45.8%; Finnish 49.8%; Middle Eastern 41.7%; Amish 49.9%.
Estimated CT genotype frequency.
Global 51.8%; European 40.6%; African 82.9%; East Asian 41.9%; South Asian 39.0%; Americas 44.9%; Ashkenazi 41.6%; Finnish 28.2%; Middle Eastern 49.6%; Amish 23.3%.
Estimated TT genotype frequency.
Showing effects for C/C genotype
Cardiovascular & Metabolic
Diabetes & Glycemic Traits
Type 2 Diabetes. Evidence: 10/10. Source: PMID 18372903. Increased Risk.
Blood Glucose. Evidence: 8/10. Source: PMID 34594039. Higher Levels.
Obesity & Body Composition
Body Mass Index. Evidence: 8/10. Source: PMID 30239722. Slightly Lower BMI.
Showing effects for C/T genotype
Type 2 Diabetes. Evidence: 10/10. Source: PMID 18372903. Slightly Higher Risk.
Blood Glucose. Evidence: 8/10. Source: PMID 34594039. Slightly Higher.
Body Mass Index. Evidence: 8/10. Source: PMID 30239722. Typical BMI.
Showing effects for T/T genotype
Type 2 Diabetes. Evidence: 10/10. Source: PMID 18372903. Typical Risk.
Blood Glucose. Evidence: 8/10. Source: PMID 34594039. Typical Levels.
Body Mass Index. Evidence: 8/10. Source: PMID 30239722. Slightly Higher BMI.
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
Carrying two C alleles results in the production of KCNJ11 proteins with valine at position 337 [1]. Large-scale genome-wide association studies have consistently linked the C allele to an increased risk of type 2 diabetes, with an odds ratio of approximately 1.08 per allele [2]. This genetic change is thought to affect the ATP-sensitive potassium channels in pancreatic beta-cells, leading to reduced insulin secretion in response to glucose [3]. Fasting blood glucose levels also tend to be higher with this genetic profile [4]. Interestingly, while diabetes risk is elevated, some studies have observed a correlation with a slightly lower body mass index [5]. ClinVar assessments confirm that this common variant does not cause severe, early-onset monogenic forms of diabetes, but rather acts as a modest risk factor for the common type 2 form [6].
Higher risk of type 2 diabetes; Elevated fasting blood glucose levels; Slightly lower average body mass index.
Sample genotype: CT (Heterozygous)
Possessing one copy of the C allele and one copy of the T allele results in a mix of valine and isoleucine at position 337 of the KCNJ11 protein [1]. Having a single C allele confers a modest increase in susceptibility to type 2 diabetes compared to the T/T genotype [2]. The genetic variation subtly alters the function of potassium channels in insulin-producing cells, which can slightly reduce the efficiency of insulin release [3]. Fasting glucose levels may be slightly elevated compared to those with the T/T genotype [4]. This genetic profile represents an intermediate risk, where lifestyle factors such as diet and exercise play a major role in determining overall metabolic health [5]. ClinVar databases classify this variant as benign for rare, severe neonatal diabetes, confirming its role is limited to a mild influence on common type 2 diabetes [6].
Moderately increased risk of type 2 diabetes; Slightly elevated fasting blood glucose levels.
Sample genotype: TT (Homozygous)
Carrying two copies of the T allele, which is the major allele globally, results in the production of KCNJ11 proteins with isoleucine at position 337 [1]. Lacking the risk-increasing C allele means having the lowest genetic risk of type 2 diabetes at this locus [2]. The potassium channels in pancreatic beta-cells function normally, maintaining typical insulin secretion patterns in response to blood sugar [3]. Consequently, fasting blood glucose levels tend to be lower and more stable [4]. However, genome-wide association studies have noted a slight correlation between this genetic profile and a higher average body mass index [5]. ClinVar classifications confirm that this common genotype is entirely benign and does not contribute to monogenic diabetes disorders [6].
Typical, lower risk of type 2 diabetes; Lower fasting blood glucose levels; Slightly higher average body mass index.
Variants with shared genetic architecture
rs5219 · KCNJ11 Gene · Chr 11 · Type 2 Diabetes Risk
rs9465871 · CDKAL1 Gene · Chr 6 · Type 2 Diabetes Risk
rs10811661 · CDKN2B Gene · Chr 9 · Type 2 Diabetes Risk
A cross-population atlas of genetic associations for 220 human phenotypes.
Association of common genetic variants of KCNJ11 gene with the risk of type 2 diabetes mellitus.
Habitual coffee intake, genetic polymorphisms, and type 2 diabetes.
Content updated August 2026.
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