DNA Testing and Diabetes
There are a few genes that have been linked to increased risk of developing diabetes. However there are only two candidates that have shown really strong association with disease risk, and only one of these has a DNA test commercially available.
One of the strongest and most robust genetic links to diabetes is certain variants of a gene called ENPP1. This was discovered way back in 2005, and is unambiguously linked to obesity and Type 2 Diabetes. But in the intervening years there is still no DNA test commercially available, and it’s not clear as to why companies aren’t offering one. There is a market for a diabetes DNA testing however and it’s currently being met by screening for variants in another diabetes linked gene; TCF7L2. This is currently available from only one source (DNA Direct) which offers a DNA test for the transcription factor 7-like 2 gene (TCF7L2). Since this is such a mouthful the product name for the DNA test is “deCode T2” after the decode consortium that found the link between this gene and Diabetes.
What can the test tell you?
Distilled to its simplest interpretation the results from your DNA test will give you an indication of how much higher than average your likelihood of developing diabetes is. How high can this be? Well figures of up to a 141% increase in risk have been reported. This sounds alarming at first glance, but let’s put this in perspective. Out of all the people that currently suffer from diabetes, only about 18% actually test positive for the T2 risk marker. So for the vast majority of patients this isn’t the driving cause of the disorder. What we can also say is that being positive for the marker certainly doesn’t guarantee that you’ll get the disease either. But information is power, and if you have this information you can certainly try to reduce your risk of disease in other way, like eating well and managing your weight carefully.
What this DNA test can also tell you is your probable response to certain classes of drugs. From DNA direct:
Studies have shown that sulfonylurea drugs (such as Amaryl, DiaBeta, Diabinese, Dymelor, Glucotrol, Glynase PresTab, Micronase, Orinase, Tolinase) work less well in people who have the T2 marker.
This information is a little less useful to you personally, but if presented to your doctor, may speed up or change your drug regimen if you are on one. The big caveat here though is that there isn’t a lot of practical evidence for patients having their treatment altered in significant ways by presenting the results of these tests to their physicians. Unsurprisingly, doctors tend to rely on their own knowledge and tests rather than some printed bit of paper handed to them by their patients.
Information is power, but for who?
So you’ve decided to get tested, and you get your results back and you find that you carry the T2 risk marker. But you don’t have diabetes, no one else in your family does either, and you’re living a healthy lifestyle.
- Are you obligated to inform your health insurance provider?
- If you change to a new health insurance company are you required to tell them?
Upon entering a health insurance contract you are usually signing a swath of documents promising that you have revealed all of your medical history, and any preexisting conditions you are aware of. But can that be applied to your knowledge of your T2 DNA test? This is where the grey area comes in. The most important factor to take note of here is that having the TCF7L2 markers is only an indication of risk of developing diabetes, and as mentioned above, it’s by no means a sure thing. Unfortunately there isn’t an easy answer to the questions above just yet. There’s lots of legislation in the pipelines to help safe guard your genetic information, and to stop it being used as a basis for discrimination. Nobody knows how these will be applied to the example above, and in all probability it will need to be tested in court before we’ll have an answer.
In the meantime the best advice is always to consult with your doctor. They’re treating lots of other people like you, and are in a great position to have an overview of the whole picture