- Design
- Diagnostic laboratory cohort with genetic risk score
- Population
- 1,129 insulin-treated people referred for MODY testing
- Primary outcome
- Estimated type 1 diabetes prevalence and score discrimination
- Effect
- About 20% type 1; AUC 0.60 overall, 0.83 under age 10
A UK genetics laboratory study looked at 1,129 insulin-treated people referred for MODY gene panel testing, all of whom also had ten variants measured to give a type 1 diabetes genetic risk score. Comparing the scores with reference populations, the authors estimated that about 20% (14.9–25.2%) of referrals actually had type 1 diabetes.
Among those whose MODY panel was negative, the enrichment rose to about 26%, and was highest in children. Age-specific thresholds flagged 16.1% of the genetically unsolved group as probable type 1 diabetes. Used before testing, the score discriminated poorly overall (AUC 0.60) but well in children under 10 (AUC 0.83), where more than half of tests could have been avoided without missing a MODY case.
The practical point is that a negative MODY panel is not the end of the diagnostic question. Antibodies, C-peptide and, where available, a genetic risk score help decide whether a young insulin-treated person is better managed as type 1.
- Check islet autoantibodies and C-peptide before a MODY referral in an insulin-treated young person.
- Treat a negative MODY panel as unsolved, not as proof of type 2 diabetes.
- In children under 10, a type 1 genetic risk score, where offered, can help avoid unnecessary panels.
- In adults the score discriminates poorly; rely on the clinical picture and biochemistry.
Why it matters
A negative MODY result can leave a person with type 1 diabetes labelled with something else.
The statistics, in plain English
An AUC of 0.5 is a coin toss and 1.0 is perfect. At 0.60 overall the score barely helps; at 0.83 in young children it separates groups well.
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