rs7903146
Type 2 diabetes, the strongest common variant
What this position does
Of the hundreds of common variants linked to type 2 diabetes, this one has by far the largest effect and has replicated in essentially every population studied. It appears to act on insulin secretion rather than on insulin resistance.
What each result means
| If you carry | What it means |
|---|---|
| No copies of the effect version CC | You have the lower-risk version on both copies Two copies of the lower-risk version. |
| One copy CT | One higher-risk copy, roughly 1.4 times the background risk Roughly 1.4 times the background risk of type 2 diabetes. Worth knowing, not worth worrying about on its own. |
| Two copies TT | Two higher-risk copies, roughly twice the background risk Roughly twice the background risk. That sounds alarming and mostly is not: lifestyle moves absolute risk far more than this does, and the Diabetes Prevention Program found that people carrying it responded to diet and exercise just as well as everyone else. An HbA1c blood test costs very little and tells you where you actually stand. |
Worth knowing. A raised probability, not a diagnosis. Blood sugar is measured with a blood test.
How common each version is
| Ancestry group | T (the effect version) | |
|---|---|---|
| African | 26.0% | |
| American | 23.5% | |
| East Asian | 2.3% | |
| European | 31.7% | |
| South Asian | 29.9% |
1000 Genomes Project phase 3, via Ensembl, retrieved 2026-09-23. These groupings are coarse and flatten a great deal of internal diversity, particularly within Africa. A variant being common somewhere tells you where a piece of your ancestry probably comes from, and nothing else.
How many people carry each result
| Ancestry group | CC | CT | TT |
|---|---|---|---|
| African | 365 / 661 | 248 / 661 | 48 / 661 |
| European | 242 / 503 | 203 / 503 | 58 / 503 |
| East Asian | 482 / 504 | 21 / 504 | 1 / 504 |
| South Asian | 240 / 489 | 206 / 489 | 43 / 489 |
| American | 205 / 347 | 121 / 347 | 21 / 347 |
Counts of people, not modelled frequencies: every one of the 2,504 individuals sequenced by the 1000 Genomes Project phase 3, tallied by the genotype they carry. Deriving these from allele frequencies instead would assume random mating inside each group and undercount the homozygotes.
How to find out which you have
If you have taken a test with 23andMe, AncestryDNA, MyHeritage, Family Tree DNA, TellMeGen or Living DNA, this position is very likely already in the raw data file they gave you. You do not need another test.
One thing to watch if you look it up by hand: testing companies report some positions from one DNA strand and some from the other, and the file does not say which. Read the letters as they appear and you will get the opposite of the truth for some positions. Sequencings resolves that automatically.
Source
Coordinates and allele pair verified against Ensembl GRCh37. Direction of effect verified against VEP protein consequences or 1000 Genomes population frequency. Category: Health-adjacent.
Where this fits
Common questions
What is rs7903146?
rs7903146 is a position in the TCF7L2 gene on chromosome 10. Of the hundreds of common variants linked to type 2 diabetes, this one has by far the largest effect and has replicated in essentially every population studied. It appears to act on insulin secretion rather than on insulin resistance.
What does it mean if I have TT at rs7903146?
Two higher-risk copies, roughly twice the background risk. Roughly twice the background risk. That sounds alarming and mostly is not: lifestyle moves absolute risk far more than this does, and the Diabetes Prevention Program found that people carrying it responded to diet and exercise just as well as everyone else. An HbA1c blood test costs very little and tells you where you actually stand.
What does it mean if I have CC at rs7903146?
You have the lower-risk version on both copies. Two copies of the lower-risk version.
How do I find out my rs7903146 genotype?
If you have taken a home DNA test, this position is very likely in the raw data file you were given. Sequencings reads that file in your browser without uploading it, and resolves which DNA strand each position was reported from, which is the step most manual lookups get wrong.
This is reference information, not medical advice, and not a diagnosis. See the medical disclaimer. Category: Health-adjacent.