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Genetic risk score may identify insulin-deficient patients
In adults with diabetes, a type 1 diabetes genetic risk score may be valuable in distinguishing between type 1 and type 2 diabetes, as well as identifying patients who are likely to develop severe insulin deficiency, according to recent findings.
“This will be an important addition to correctly classifying individuals with diabetes and will improve the number of people who get the right treatment when they are first diagnosed, especially people who sit in the overlap between type 1 and type 2 diabetes,” Richard A. Oram, PhD, from the University of Exeter Medical School, United Kingdom, said in a press release. “There is often no going back once insulin treatment starts. This may save people with type 2 diabetes from being treated with insulin unnecessarily, but also stop the rare but serious occurrence of people with type 1 being initially treated with tablets inappropriately and running of the risk of severe illness.”
In the study, Oram and colleagues tested genetic risk scores they had developed on participants in the Wellcome Trust Case Control Consortium. The type 1 diabetes genetic risk score was based on 30 single nucleotide polymorphisms (SNPs) associated with type 1 diabetes risk, whereas the type 2 diabetes genetic risk score was generated using 69 SNPs associated with type 2 diabetes. The researchers first tested the ability of the genetic risks scores to differentiate between type 1 diabetes and type 2 diabetes in the cohort (n = 3,887) and then evaluated the type 1 diabetes genetic risk score in a cohort of 223 patients aged 20 to 40 years diagnosed with diabetes. In this population, the type 1 diabetes genetic risk score was assessed for diagnostic efficacy in identifying severe insulin deficiency.
The researchers found that in the testing on the cohort, there was a high level of discrimination for type 1 and type 2 diabetes with the type 1 diabetes genetic risk score, with an area under the curve (AUC) of 0.88 (P < .0001). The type 2 diabetes genetic risk score demonstrated less discrimination (AUC, 0.64) and added only negligible discriminatory power to the type 1 diabetes genetic risk score. For this reason, the researchers focused the remainder of the analyses on the type 1 diabetes genetic risk score.
In the cohort of 223 participants, the type 1 diabetes genetic risk score was highly discriminatory (AUC, 0.87). A type 1 diabetes genetic risk score of more than 0.28 was 92% specific and 54% sensitive for severe insulin deficiency with a positive predictive value of 63% and a negative predictive value of 88%. A type 1 diabetes genetic risk score of less than 0.234 was 96% specific and 56% sensitive for the absence of severe insulin deficiency.
Only nine SNPs were responsible for most of the discriminative ability of the genetic risk score (AUC, 0.87). Type 1 diabetes genetic risk score alone was predictive of disease advancing to insulin deficiency (P < .0001).
According to the researchers, the genetic risk score may enable patients with diabetes to have more insight into their condition.
“Having this information about their diabetes and about their genetic risk will make a big difference to the way people feel about their care,” Oram said in the release. “If you speak to people with diabetes they often want to know why they have developed the disease and whether some of their risk for the disease is genetic.” – by Jennifer Byrne
Disclosure: Oram reports being supported by a Diabetes U.K. Clinical Training Fellowship and an Alberta Health Services Transplant Fellowship. Please see the full study for a list of all other authors’ relevant financial disclosures.