Genetic Risk Score Identifies Type 1 Diabetes in MODY Testing

Accurately distinguishing maturity-onset diabetes of the young from type 1 diabetes is difficult in routine care, especially when onset occurs in adolescence or early adulthood. Although maturity-onset diabetes of the young (MODY) typically results from a single gene change and is often suspected in patients diagnosed before age 25, most referrals return negative results, leaving the cause uncertain. This diagnostic gray zone can delay tailored management and prompt additional testing. New findings demonstrate that adding a type 1 diabetes genetic risk score to standard MODY workflows can uncover otherwise hidden type 1 cases.

At the University of Exeter, investigators evaluated a type 1 genetic risk score—developed at Exeter—for use alongside routine MODY gene panel testing. The score is introduced as a cheap, simple tool that considers all known genetic risk factors for type 1 diabetes. Applied after a negative MODY result, it is intended to provide an additional route to diagnosis within existing laboratory pathways.

In a study of more than 1,100 insulin-treated individuals referred for MODY testing, approximately 80% received a negative genetic result with no clear explanation. Among those with negative results, the score indicated that 16%—around 180 people—had atypical type 1 diabetes. Incorporating the score into routine testing could enable genetic laboratories to issue a type 1 diabetes diagnosis for patients who previously would have received no explanation, and the approach will now be adopted as part of NHS testing.

The work was published in Diabetes Care on August 18, 2026. The study and clinical translation were supported by the Exeter Genomics Laboratory at the Royal Devon University Healthcare NHS Foundation Trust. Additional clinical perspectives were provided by Gloucestershire Hospitals NHS Foundation Trust and Diabetes UK.

“In clinic, it’s extremely challenging to distinguish between MODY and type 1 diabetes, yet getting the right diagnosis is crucial to getting the right treatment. We found that applying the type 1 genetic risk score to patients who tested negative for MODY is effective in identifying patients with type 1 diabetes, reducing the need for expensive further testing and providing answers to patients,” said Kashyap Patel, associate professor at the University of Exeter and consultant physician in diabetes and endocrinology.

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