Diabetes caused by mutations in the HNF1-alpha gene (encoding hepatocyte nuclear factor-1 alpha) is one of the most common types of MODY. This gene contains is a blueprint for a transcription factor that is important in for the normal development of beta cells.


MODY 3 is typically diagnosed before 30 years of age and is often misdiagnosed as Type 1 diabetes mellitus. MODY 3 usually manifests with symptoms associated with high blood sugars. These include increased frequency of urination (polyuria), increased thirst (polydipsia), and weight loss.

Mutations can occur spontaneously but usually are passed on from a parent to a child. If a parent has MODY 3 there is a 50% chance that a child will inherit the mutation and be at risk of developing diabetes at a young age.

Distinguishing MODY 3 from Type 1 diabetes can be difficult. Features that make us suspect MODY 3 include

  • Negative antibody testing
  • Persistently detectable C-Peptide
  • 2 or 3 generations of diabetes diagnosed at a young age
  • High sensitivity to sulfonylurea medications
  • No history of diabetic ketoacidosis


Many patients with MODY 3 can be successfully treated for years with low doses of sulfonylurea medications. Diagnosing somebody with MODY 3 can sometimes allow a change in treatment with some patients changing from insulin therapy to tablets (sulfonylurea medications).


Finding an HNF1A mutation in a patient’s family may have implications for other family members- who may be carriers as well. An affected person’s child will each be at a 50% risk of inheriting the mutation and developing diabetes.


If you or a family member have MODY 3 or suspect yourself or a family member of having MODY 3 then please contact us to learn more about our studies.