Tip of the Iceberg: Are We Missing Undiagnosed MODY Patients?

Understanding MODY: A Hidden Challenge in Diabetes Diagnosis

Maturity Onset Diabetes of the Young (MODY) is the most common genetic form of diabetes, yet it remains underdiagnosed. Affecting around 2–3% of all diabetes patients, MODY is often clinically indistinguishable from Type 1 or Type 2 diabetes, making accurate diagnosis challenging without molecular genetic testing.

Currently, 14 genes have been implicated, and treatment pathways differ depending on the subtype. For example:

• MODY1 and MODY3: Respond well to sulfonylureas.
• MODY2: Often requires no treatment outside of pregnancy.

A Case Study: Diagnostic Delay and its Real-World Impacts

A young woman’s journey to diagnosis highlights systemic gaps:

• Diagnosed at 17 years old with presumed Type 1 diabetes, despite:
  • Negative autoantibodies
  • Stable C-peptide levels
  • Absence of DKA history
• Despite multiple relocations and consultations, requests for MODY testing were dismissed because “it wouldn’t change management.”
• Her MODY Calculator Risk Score was 4.9%.

Finally, through participation in a research trial, genetic testing confirmed a pathogenic HNF1A mutation, diagnosing her with MODY3.

Reflection on the Missed Opportunity

Upon receiving the correct diagnosis, the patient shared:

“The realisation that I could have avoided 28,000 insulin injections and the associated costs, stress, and complications is overwhelming.”

Emerging Evidence: Higher Diagnostic Yields

Preliminary trial findings showed a 21% MODY diagnostic yield among eligible participants, underlining:

• The critical need for clinical guideline development in Australia.
• The opportunity to streamline diagnosis and optimize diabetes management.

• Negative autoantibodies AND:
  • Detectable C-peptide

Why It Matters: Moving Towards Better Patient Outcomes

Accurate MODY diagnosis means:

• Tailored therapy (reducing unnecessary insulin use)
• Improved patient quality of life
• Cost savings for healthcare systems

Australian endocrinology practice must adapt by broadening testing access and awareness — ensuring MODY no longer remains the tip of the iceberg in diabetes care.

Sources: Internal Medicine Journal, 2022​.