Frequently asked questions

What is deCODE T2™?
deCODE T2™ is a reference laboratory test that measures four of the strongest gene markers validated for elevated risk of developing T2D independent of other risk factors,  and identifies as well those prediabetics most likely to progress to full-blown T2D.  The DNA markers included in deCODE T2™ are located in or near the following genes: TCF7L2, PPARG, CDKAL1, and CDKN2A and have each been widely replicated in 10 to 40 independent populations. 

What is a reference laboratory test?
deCODE T2™ is a reference laboratory test, which means that a sample is sent to our laboratory for analysis. The test itself is not performed in a doctor’s office.

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Is deCODE T2™ an FDA approved test?
No, this is a reference laboratory test that has not been cleared or approved by the FDA. Our laboratory is registered through the Clinical Laboratory Improvement Amendments (CLIA) program. The possible utility of this test as a means of assessing inherited susceptibility to type 2 diabetes, as presented on this site and elsewhere, is based upon published studies by deCODE and independent researchers demonstrating the correlation of carrying the measured risk variants and increased likelihood of type 2 diabetes. This correlation has been demonstrated in more than 10 -40 independent cohorts of patient across multiple populations and ethnic groups from around the world.

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Who can order the test?
If you are an individual interested in deCODE T2™, you can sit down with your doctor and continue through this site, or go to our partner, www.DNAdirect.com to learn more. DNAdirect will provide you with all the professional services needed to obtain the test and interpret its results from the convenience of your home. With DNA Direct, you order the test online, receive a cheek swab test kit by mail, and consult with board-certified genetic specialists toll-free and by email. Along with your test results, DNA Direct will provide you with a web-based, personalized guide to help you understand your results and a Physician Letter with clinical information to take to your doctor.

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How does the testing process work?
The testing process involves a few simple steps. First, and very importantly, the person who is being tested must give his/her signed, informed consent for the test to be ordered. That means that an individual needs to review the informed consent form that explains what the test is for and what the results may mean. The person being tested must also have the opportunity to have any questions they may have answered to their satisfaction before deciding whether or not they wish to be tested. Once the individual has signed the informed consent, a testing sample needs to be collected, most likely a small tube of blood, which is then sent to deCODE for analysis.

The results will be reported back to the doctor within 3-8 weeks from the time the sample is sent, and the doctor will then report the results to the individual and explain what they mean and how they may be used as part of a diabetes prevention regime. The same process applies if the test is ordered through DNA Direct, though the individual being tested would submit a sample with a cheek swab by mail, rather than with a blood sample drawn at a doctor’s office or clinic.

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What do the results mean?
It is important to bear in mind that common diseases, such as type 2 diabetes, occur as a result of the interplay of both environmental (including lifestyle and other health and medical conditions) and inherited risk factors. As a result, having a specific genetic risk factor for a common disease does not mean that one will necessarily develop the disease; and not having a certain risk variant does not eliminate the possibility of developing the disease. Rather, in the common diseases, genetic risk variants impact the likelihood that one may develop a given condition.

deCODE T2TM, like other DNA based tests for common disease, is therefore a risk assessment test as it measures DNA risk markers that are not determinative but associate with the disease in certain proportion of the patients. Patients with higher genetic risk are not destined to develop T2D and conversely, patients with lower genetic risk are not immune from diabetes. There are other risk factors not measured by the deCODE T2TM test.  DNA markers for common disease simply are risk markers just as blood cholesterol is for cardiovascular diseases or PSA for prostate cancer.

The deCODE T2™  genetic risk profile is independent of other risk factors for type 2 diabetes such as family history, obesity, prediabetes, and ethnicity.  The genetic risk can be multiplied by the other risk factors not measured by the test to derive a composite risk relative to that in the general population.   Therefore, this test is useful for patients with or without family history of T2D.
The deCODE T2TM results defines risk range from 0.6 to 2.2 fold the risk of the general population.   About 40 % of the population has a genotype combination of the tested markers that have an increased relative risk (>1) over the general population, about 8% of the population have 1.5 to 2.2 relative risk, about 3% of the population have genotype combinations that confer a 1.8 to 2.2 fold relative risk.

By knowing and understanding genetic risk, it may be possible to take actions that reduce or minimize the likelihood of individual developing diabetes.

In addition to predicting or recalculating the remaining lifetime risk of developing T2D, the deCODE T2TM results can predict the likelihood of those with prediabetis (impaired fasting glucose and impaired glucose tolerance)  converting to full blown T2D and which patients may benefit the most from preventive management. Compared to the baseline risk of 30% in overweight or obese prediabetics to convert to T2D within 3 to 4 years deCODE T2 TM can identify those prediabetic patients who are at up to 70 % risk of converting to T2D within the same timeframe. These high-risk patients therefore may benefit the most from more aggressive management either through lifestyle modification or drug treatment.  The American Diabetic Association states in it’s 2008 recommendations on management of prediabetics, that in addition to lifestyle counselling, treatment with the T2D drug metformin may be considered in those who are at very high risk and who are obese and under 60 years of age.  deCODE T2 TM is one of the strongest risk factors for conversion.

Understanding this inherited risk is empowering information*, as it may be used to target and emphasize the importance of preventive action – including weight loss, getting more exercise, eating better, and perhaps taking certain medications – to minimize the likelihood of an inherited predisposition to T2D ever developing into T2D. Analysis of data from a U.S. government-funded clinical trial involving prediabetics (individuals with blood glucose levels that are intermediate between normal and type 2 diabetes) showed that the increased genetic risk signalled by the deCODE T2™ test could be reduced through an effective weight loss regime, and that this reduction was even more significant than it was for those without one or no copies of the risk variant. Analysis of this clinical trial (the Diabetes Prevention Program) also demonstrated that even in those who did not lose weight, drug treatment with certain medications that boost insulin response reduced progression rates of prediabetics to T2D.
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Should test results be interpreted differently for different ethnic groups?
Only the TCF7L2 (one of the genes tested in deCODE T2TM) associated risks have been validated in multiple races and show similar effect in whites, Africans, Hispanics, and Asian populations. CDKAL1 and CDKN2 seem to have equivalent effects in whites (European descent) and Asians.  PPARG has so far only been validated in whites.
Both deCODE’s studies and many studies of independent research groups have shown that the association of the TCF7L2 gene variant and the likelihood of developing diabetes is quite similar across a wide variety of ethnic groups. However, the average frequency of carrying two copies, a positive result for the test, appears to vary according to ethnicity. As a consequence ethnicity has an effect on the likelihood of testing positive for carrying two copies of the variant, but no significant impact on the magnitude of risk conferred by the variant.

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Will anyone else know the results of my test?
deCODE takes your privacy seriously, and our testing process is designed to ensure that it is the individual being tested who designates those to whom the results will be reported. deCODE will report results only to the physician(s) and/or healthcare institution(s) specified on the test request form and as confirmed by the individual in his/her informed consent.

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What is this test based on?
The test is based deCODE’s genetics and others discoveries of genetic variants that carry with them increased risk for the development of T2D. Multiple research studies by independent researchers have validated the results in tens of thousands of people from populations around the globe (Remember that we all have two copies of each chromosome in every cell in our bodies. We inherit one copy from our mother, and one from our father.)

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What is a genetic risk factor for a common disease and why is understanding genetic risk important in a disease such as T2D?
A genetic risk factor for a common disease is a specific version of a marker in the sequence of the genome that causes or correlates with an increased likelihood of developing a given disease. Common diseases such as type 2 diabetes (T2D) occur at the interface of genes and the environment, as both inherited as well as lifestyle and other health risk factors play important roles in the disease process. As a result, it is important to understand what carrying an inherited risk variant for a common disease means, and how that information can be used to develop and implement disease prevention strategies that can effectively reduce the likelihood of an individual ever developing the disease.

In basic terms, carrying a genetic risk variant for a common disease does not mean that one will necessarily develop the disease; and not having a certain risk variant does not eliminate the possibility of getting the disease. Rather, for the common diseases, genetic risk variants impact the likelihood that one may develop the disease. Understanding this inherited risk is empowering information* with potentially important clinical utility. This is particularly true in a disease like T2D, in which specific lifestyle and health factors are known to play such an important part. By understanding inherited risk, it may be possible to take preventive action – through lifestyle modification or by taking certain medications – to maximize the chances of staying healthier longer. This is similar to the approach that is taken to address other risk factors for common diseases, such as high cholesterol, which is commonly treated using statin drugs to lower the risk of heart disease.

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Who might benefit from this test?
The incidence of type 2 diabetes is rising rapidly in the United States and throughout the industrialized world. The increasing prevalence of T2D is believed to be due in large measure to the rapid increase in obesity and to more sedentary lifestyles in general. Yet while obesity, lack of exercise and high-calorie diet are all major known risk factors, it has long been recognized that certain individuals are more susceptible to developing T2D than others, even after accounting for shared lifestyle and health factors. This differential is the hallmark of the impact of genetic risk factors.

Many of us need to lose weight, get more exercise and improve our diet. And because of these and other lifestyle and medical conditions, many of us are at increased risk of developing T2D. Studies have shown that even those who have increased genetic risk according to their deCODE T2™ results can overcome that risk by loosing weight.

Individuals who are already prediabetic, with fasting plasma glucose levels of between 100 and 125 mg/dL and/or impaired glucose tolerance, are at even higher risk. But while losing weight and other lifestyle modifications are difficult, a better understanding of who is at increased risk of T2D through genetic factors may provide individuals and their doctors additional information and incentive to implement and stick to preventive regimes that can reduce the risk of T2D, possibly including certain existing medications aimed at preventing the onset of T2D.

deCODE T2™ measures four of the strongest gene markers validated for elevated risk of developing T2D independent of other risk factors. 

About 40 % of the population has a genotype combination of the tested markers that have an increased relative risk (>1) over the general population, about 8% of the population have 1.5 to 2.2 relative risk, about 3% of the population have genotype combinations that confer a 1.8 to 2.2 fold relative risk.

In addition to predicting or recalculating the remaining lifetime risk of developing T2D, the deCODE T2TM results can predict the likelihood of those with prediabetis (impaired fasting glucose and impaired glucose tolerance)  converting to full blown T2D and which patients may benefit the most from preventive management. Compared to the baseline risk of 30% in overweight or obese prediabetics to convert to T2D within 3 to 4 years deCODE T2 TM can identify those prediabetic patients who are at up to 70 % risk of converting to T2D within the same timeframe. These high-risk patients therefore may benefit the most from more aggressive management either through lifestyle modification or drug treatment.  The American Diabetic Association states in its 2008 recommendations on management of prediabetics, that in addition to lifestyle counselling, treatment with the T2D drug metformin may be considered in those who are at very high risk and who are obese and under 60 years of age.  deCODE T2 TM is one of the strongest risk factors for conversion.

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What scientific publications support the value of this test?
deCODE is widely recognized as the world leader in the discovery of genes contributing to risk of common diseases. deCODE has also led the way in publishing its discoveries, a commitment that not only drives ongoing research but also enables independent researchers from around the globe to validate the company's discoveries.

deCODE T2™ risk results conferred by each variant are separately derived from the published results of thousands of patients and controls genotyped in the same way (Grant, S.F., et al., Nat Genet, 2006. 38(3): p. 320-3. Steinthorsdottir, V., et al. Nat Genet, 2007. 39: p. 770-776. Zeggini, E., et al., Science, 2007;  316(5829):1336-1341. Saxena, R., et al., Science, 2007, 316(5829):1331-1336. Scott, L.J., et al., Science, 2007;316(5829):1341-1345.Altshuler, D., et al. Nat Genet, 2000. 26(1): p. 76-80) and have been replicated in numerous published studies in a wide variety of populations and ethnic groups.

A list of key publications in regard to reproducibility and clinical relevance includes:

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Payment and Reimbursement
Payment can be made by any major credit card by the individual or by the ordering physician or clinic, by including the card details on the test request form. Samples submitted anonymously must be accompanied by a valid credit card number from the respective doctor or affiliated health care institution.

deCODE plans to make the deCODE T2™ as widely available as possible and is working with physicians, patients, and their insurers on reimbursement for deCODE T2™. For more information contact customer service at diagnostics@decode.com, or by phone at 1-877-222-6510

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Who can I contact if I have further questions?
deCODE offers this test via doctors so that individuals will understand what the test is for, what the results mean, and to integrate the testing process into an effective T2D prevention regime. However if you or your doctor have additional questions regarding the test, please contact deCODE at diagnostics@decode.com, or by phone at 1-877-222-6510 and a deCODE representative will respond promptly to your questions. deCODE T2™ can also be ordered through DNA Direct at www.dnadirect.com, who provide comprehensive services to enable individuals to have the test performed and to understand end utilize the results.