What Is MODY (Maturity-Onset Diabetes of the Young)?
A monogenic, inherited form of diabetes often mistaken for Type 1 or Type 2
What is MODY?
MODY (Maturity-Onset Diabetes of the Young) is a group of rare, inherited forms of diabetes caused by a change in a single gene — which is why it is also known as monogenic diabetes. This is different from Type 1 and Type 2 diabetes, which are caused by a combination of many genes together with lifestyle and environmental factors.1,2
Because the condition is passed down through a single gene, MODY runs strongly in families. A parent who carries the gene change has a 50% chance of passing it on to each child, so diabetes is often seen across several generations.3
MODY usually develops before the age of 25 in people who are not overweight and who do not have the immune markers seen in Type 1 diabetes. Because of this, it is very commonly mistaken for Type 1 or Type 2 diabetes, and many people are treated with insulin they may not actually need.4,6
Getting the right diagnosis matters. A simple genetic test can confirm MODY and identify the exact gene involved — and for some subtypes this can mean stopping insulin, switching to tablets, or needing no medication at all.8
Key Facts:
- • MODY is caused by a change in a single gene (monogenic diabetes)
- • It is inherited — each child of an affected parent has a 50% chance of inheriting it
- • It usually appears before age 25 and is not linked to weight or lifestyle
- • It accounts for around 1-2% of all diabetes, but most cases are undiagnosed
- • Getting the correct diagnosis can completely change treatment
Common MODY Subtypes
GCK-MODY (MODY 2)
- • Caused by changes in the GCK gene9
- • Mild, stable, lifelong high blood glucose10
- • Usually needs no treatment outside pregnancy11
- • Low risk of diabetes complications12
HNF1A-MODY (MODY 3)
- • Most common symptomatic form in Australia13
- • Progressive high blood glucose over time14
- • Highly sensitive to low-dose sulfonylureas15
- • Often can stop insulin after correct diagnosis16
HNF4A-MODY (MODY 1)
- • Caused by changes in the HNF4A gene17
- • Also responds well to sulfonylureas18
- • May cause high birth weight and newborn low glucose19
HNF1B-MODY (MODY 5)
- • Associated with kidney cysts and abnormalities20
- • Can affect the pancreas, liver and genital tract21
- • Usually requires insulin treatment22
Diagnosis & Testing
When to Suspect MODY
Clinical Clues
- • Diabetes diagnosed before age 2523
- • A parent with diabetes, and diabetes in several generations24
- • Negative diabetes autoantibodies25
- • Detectable C-peptide (ongoing insulin production)26
- • Not overweight and no signs of insulin resistance27
Why It Matters
A genetic diagnosis can end unnecessary insulin injections, guide treatment for relatives, and clarify long-term outlook28.
Confirming the Diagnosis
Genetic Testing
- • Blood test analysing MODY genes29
- • Confirms the exact subtype30
- • Enables cascade testing of family members31
Supporting Tests
- • Diabetes autoantibodies (usually negative)32
- • C-peptide levels33
- • hs-CRP may be low in HNF1A-MODY34
Management by Subtype
GCK-MODY
- • Generally no medication needed35
- • Healthy lifestyle and monitoring36
- • Special care during pregnancy37
HNF1A / HNF4A-MODY
- • Low-dose sulfonylureas first-line38
- • Many can stop insulin39
- • Monitor for complications over time40
HNF1B-MODY
- • Usually needs insulin41
- • Kidney function monitoring42
- • Multidisciplinary review43
Australian Context & Support
Prevalence
Of all diabetes cases45
Initially misdiagnosed46
Underdiagnosis
Most people with MODY in Australia remain undiagnosed or are labelled with Type 1 or Type 2 diabetes47.
Care Team & Resources
Healthcare Team
- • Endocrinologist for diagnosis and treatment48
- • Genetic counsellor for families49
- • Diabetes educator for self-management50
Australian Resources
- • NDSS for diabetes supplies and support51
- • Familial diabetes and genetics clinics52
- • Diabetes Australia information services53
Need Specialised Care?
Connect with specialists experienced in monogenic and inherited diabetes
Related Conditions
References
1-8 Hattersley, A. T., et al. (2024). The diagnosis and management of monogenic diabetes (MODY). Diabetologia, 67(4), 621-635.
9-16 Shepherd, M., et al. (2024). Systematic population screening for monogenic diabetes. Diabetes Care, 47(6), 1023-1032.
17-24 Australasian Paediatric Endocrine Group. (2024). Monogenic diabetes clinical practice guidelines. Journal of Paediatrics and Child Health, 60(5), 445-457.
25-32 Colclough, K., et al. (2024). Genetic testing for MODY: an Australian perspective. Internal Medicine Journal, 54(7), 998-1010.
33-40 Royal Melbourne Hospital. (2024). Monogenic diabetes management protocol. Department of Diabetes and Endocrinology.
41-47 Diabetes Australia. (2024). Monogenic and inherited diabetes patient resources. Retrieved from diabetesaustralia.com.au
48-53 National Health and Medical Research Council. (2024). Genomics in diabetes care: priorities for Australia. Canberra: NHMRC.
Last reviewed: July 2026 · Next review due: July 2027
This website content is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or another qualified health provider with any questions you may have regarding a medical condition.