SLC22A1 rs3798167: What Your Genotype Means
The rs3798167 variant is a genetic change located within the SLC22A1 gene, which provides instructions for making the Organic Cation Transporter 1 (OCT1) protein. Research has investigated this variant for its potential association with gastrointestinal side effects and glycemic response in individuals taking the medication metformin.
What each genotype means
Typical metformin transport profile
This genotype represents the most common form of the SLC22A1 gene in many populations. Research into this variant suggests that individuals with this profile may have a standard baseline for metformin transport in the gut. Please discuss your medication response and any gastrointestinal symptoms with your healthcare provider, as individual experiences with metformin can vary significantly regardless of genetics.
This is the most common genotype observed across most global populations.
Potential altered transport sensitivity
Carrying one copy of the T allele may be associated with differences in how the body transports metformin in the gastrointestinal tract. Studies have explored whether such variants contribute to gastrointestinal intolerance, though the evidence remains limited and inconsistent across different groups. You should consult your clinician or pharmacist regarding your specific medication regimen and any side effects you may experience.
This genotype is found at varying frequencies depending on ancestral background, appearing in a significant portion of the population.
Increased potential transport sensitivity
Individuals with this genotype carry two copies of the T allele, which has been investigated for its potential role in metformin-related gastrointestinal side effects. Because the evidence linking this specific variant to clinical outcomes is limited, it is not used to predict individual drug response definitively. Always discuss your treatment plan and any persistent side effects with your doctor to ensure your medication is working effectively for you.
This genotype is less common than the CC or CT genotypes and its frequency varies notably across different global populations.
Understanding the Variant and Gene
The rs3798167 variant is a single nucleotide polymorphism (SNP) found within the SLC22A1 gene, located on chromosome 6. This gene encodes the Organic Cation Transporter 1 (OCT1), a protein primarily expressed in the liver. OCT1 acts as a gateway, facilitating the uptake of various substances, including certain medications, from the bloodstream into liver cells. Because metformin relies on this transporter to enter the liver—where it exerts its primary blood-sugar-lowering effects—variations in the SLC22A1 gene are of significant interest to pharmacogenomics researchers. By altering the structure or expression of the OCT1 protein, genetic variants like rs3798167 may influence how efficiently a person's body processes metformin, potentially impacting both the drug's therapeutic efficacy and the patient's experience with side effects.
Research and Evidence Strength
Scientific literature has explored the link between SLC22A1 variants and metformin outcomes, though the evidence for rs3798167 specifically remains limited. Some studies suggest that reduced-function variants in this gene are associated with diminished glycemic responses, meaning some individuals may require higher doses or alternative treatments to reach their blood sugar targets. Regarding side effects, gastrointestinal issues such as diarrhea, nausea, and abdominal discomfort are common with metformin use. Researchers have hypothesized that genetic differences in OCT1 might influence the concentration of metformin in the gut or liver, potentially contributing to these symptoms. However, it is important to note that the evidence connecting rs3798167 directly to these side effects is not definitive. Pharmacogenetic associations can be complex, often influenced by other genetic factors, diet, and the specific formulation of the medication being used.
Population Frequency
The frequency of the rs3798167 variant is known to be variable across different global populations. Genetic databases like gnomAD provide insights into how common specific alleles are within various ancestral groups, which is crucial for understanding the potential impact of a variant on a global scale. Because allele frequencies can differ significantly between populations, a variant that is common in one group may be rare in another. Researchers use this data to ensure that pharmacogenetic studies are representative and to avoid making broad generalizations that do not account for human genetic diversity. For rs3798167, individuals should be aware that their specific ancestral background may influence the likelihood of carrying this variant, and ongoing research continues to refine these frequency estimates to improve the accuracy of genetic testing.
Navigating Your Genetic Information
It is essential to understand that genetic variants are only one piece of a much larger puzzle regarding medication response. While pharmacogenomics is a growing field, the presence of a specific genotype does not guarantee a particular clinical outcome. You should never use genetic information to make decisions about your medication, such as stopping or changing your dose, without consulting your healthcare provider. If you are concerned about side effects or the effectiveness of your metformin treatment, speak with your doctor or pharmacist. They can evaluate your symptoms, review your medical history, and determine the best course of action for your specific health needs. Genetic testing for drug response is a tool for clinical guidance, not a substitute for professional medical advice or a diagnostic test for diabetes management.
How common is this variant?
The frequency of the rs3798167 variant is variable across global populations, and users should consult databases like gnomAD for the most current, ancestry-specific frequency data.
Frequently asked questions
Can this genetic test tell me if metformin will work for me?
Genetic testing for SLC22A1 provides information about your potential response to metformin, but it cannot predict your exact clinical outcome. Many factors, including diet, lifestyle, and other genes, influence how well a medication works for you.
Should I stop taking metformin if I have this variant?
No. You should never stop or change your medication based on genetic results without speaking to your doctor. Your healthcare provider is the only person who can safely adjust your treatment plan.
Are gastrointestinal side effects always caused by my genetics?
Not necessarily. Gastrointestinal side effects are very common with metformin and can be caused by many factors, including how the medication is taken, the dosage, and individual sensitivity. Genetics is only one potential contributing factor.
Where can I find more information about pharmacogenomics?
You can find reliable information through resources like PharmGKB, MedlinePlus Genetics, and the CPIC guidelines. These organizations provide evidence-based summaries on how genes affect drug response.
Sources & further reading
Educational information only, last refreshed 9/25/2026. Not medical advice — these associations describe population statistics, not individual predictions.
Curious what your genotype is for rs3798167?
Upload a raw DNA file from 23andMe, AncestryDNA, MyHeritage, or FamilyTreeDNA and see this variant — plus thousands more — interpreted in your full report.
Get my report — $29Related variants in SLC22A1
An intronic variant in the organic cation transporter gene associated with altered metformin side-effect profiles.
This variant in the SLC22A1 gene is associated with altered transport and response to the drug metformin.
Also known as OCT1 p.Met420del, this loss-of-function deletion directly diminishes hepatic uptake and glycemic response to metformin in patients with type 2 diabetes.
This SNP is investigated alongside rs72552763 for its role in modulating glycemic response and HbA1c levels in diabetic patients treated with metformin.
A missense variant in OCT1 that impairs organic cation cellular uptake, altering clinical responsiveness and gastrointestinal tolerance to metformin.
A well-characterized loss-of-function variant (M420del) in the organic cation transporter 1 (OCT1) that reduces hepatic uptake of metformin and other basic drugs, modulating therapeutic efficacy and side effects.