Genetic score finds hidden type 1 diabetes after negative MODY tests

A blood sample sent for MODY testing can answer one question and leave another hanging. At the University of Exeter, researchers found that adding a type 1 diabetes genetic risk score to the existing test identified 16% of patients whose MODY gene panel was negative as having atypical type 1 diabetes—around 180 patients in the study.

MODY, or maturity-onset diabetes of the young, is caused by a change in a single gene and is often diagnosed before age 25. Yet about 80% of people referred for a MODY test receive a negative result, leaving the cause of their diabetes uncertain. The study examined more than 1,100 people being treated with insulin and referred for genetic testing.

The added score is designed to estimate the risk of type 1 diabetes by taking into account all known genetic risk factors. The University of Exeter describes it as a cheap and simple analysis that can run alongside the established MODY testing process, giving laboratories another diagnostic signal when the main gene panel finds no answer. The findings were published in Diabetes Care.

So what changes in practice? For patients with an unexplained negative MODY result, the score could provide a clearer diagnosis without the need for expensive further testing. That can help clinicians target treatment and support more individually, rather than managing a diagnosis marked mainly by uncertainty. The Exeter MODY testing service, led clinically by Kevin Colclough at the Royal Devon University Healthcare NHS Foundation Trust, will incorporate the approach into NHS testing.

The study was led by Kashyap Patel, an associate professor at the University of Exeter and consultant physician in diabetes and endocrinology. Its reach has a clear boundary: the participants were insulin-treated people already referred for MODY testing, not everyone with diabetes. Even so, the work shows how a research-developed risk score can move into a routine clinical pathway and turn a negative genetic result into more useful information.