Maturity Onset Diabetes of the Young (MODY)

What is MODY?

Maturity Onset Diabetes of the Young (MODY) is a rare form of diabetes caused by changes in the DNA that are passed down in families.

People with MODY tend to develop diabetes a younger age (usually before age 30), however the condition is often not recognized and can be misdiagnosed as type 1 or type 2 diabetes.

Making the diagnosis of MODY is important because it may impact treatment.

What causes MODY?

Mutations in certain genes cause MODY. Clinical genetic testing is available for the genes that most commonly cause the disease, which include HNF1A, GCK, HNF4A, PDX1, and HNF1B.

What are the risk factors for MODY?

Risk factors for MODY include:

• Age, typically onset of diabetes before age 30
• Strong family history of diabetes (often a parent affected)
• Normal weight (as compared to patients with type 2 diabetes often being overweight)
• Negative diabetes antibody results (as compared to type 1 diabetes)
• Detectable C-peptide many years after diagnosis
• Chronic mildly elevated fasting blood sugars (100-140 mg/dl)

What are the symptoms of MODY?

Symptoms of MODY may include:

• Symptoms of type 1 or type 2 diabetes
• Many individuals with MODY have no symptoms at all. Particularly those with mutations in GCK MODY may never develop any symptoms.

How is MODY diagnosed?

MODY is diagnosed with a blood test that looks for alterations in the genes that most commonly cause the disease, including HNF1A, GCK, HNF4A, PDX1, and HNF1B.

Genetic testing is offered at the Mass General Diabetes Genetics Clinic. Since MODY is rare and genetic testing is expensive, it is recommended that patients be assessed by a clinician familiar with the condition before testing is pursued.

How is MODY treated?

Your health care provider will recommend treatment based on which gene is causing the condition:

• GCK MODY: No treatment is necessary. Blood sugars remain mildly elevated, but it is not thought to be dangerous or lead to typical diabetic complications.
• HNF1A and HNF4A MODY: Patients often respond well to a pill called a sulfonylurea. If a patient is already on insulin, sometimes the insulin can be stopped, and instead the patient’s sugars can be controlled with the sulfonylurea pill.

What are the complications of MODY?

Except for GCK MODY, all other forms of MODY have the same complications as type 1 and type 2 diabetes. GCK MODY is not thought to cause any clinically important complications.

Key points

• MODY is a rare form of diabetes that typically develops before age 30.
• It is often misdiagnosed as type 1 or type 2 diabetes.
• It is diagnosed with a blood test sent for genetic testing.
• A diagnosis can impact treatment.

Learn more

The following websites provide more information on MODY:

• National Institute of Diabetes and Digestive and Kidney Diseases
• Diabetes Genes
• University of Chicago

• Email Dr. Miriam Udler at mudler@partners.org