Maturity-Onset Diabetes of the Young (MODY)

MODY (maturity-onset diabetes of the young) is a type of diabetes. A change in one of your genes that affects how you make insulin causes it. For this reason, MODY is classified as a type of monogenic diabetes. Experts believe between 2% and 5% of people with diabetes have MODY. Healthcare providers most often diagnose it in people under 30. It can be mistaken for Type 1 or Type 2 diabetes. But MODY has a different cause from the more common types of diabetes.

Treatment for MODY depends on the type of MODY you have. It could involve lifestyle changes, oral medication or insulin injections.

The term “maturity-onset diabetes of the young” is misleading. When it was first discovered, researchers thought it was a form of Type 2 diabetes affecting young people. Now, they know it’s due to a change in a single gene. Experts are moving towards using the affected gene to specify the form of monogenic diabetes.

Types of MODY

There are at least 14 gene changes that cause MODY. Knowing the subtype you have can help guide your treatment plan. It can also predict how the disease may progress.

The most common subtypes are:

• HNF4-MODY (MODY1): This type leads to progressive loss of insulin. Treatment begins with oral medication, but you may eventually need insulin.
• GCK-MODY (MODY2): This is the second most common cause of MODY. About 3 in 10 people with MODY have MODY2. It leads to mildly high blood sugar (glucose) that may not eventually need treatment. You may not have any symptoms.
• HNF1A-MODY (MODY3): This gene is the most common cause of MODY. Up to 6 in 10 people with MODY have this type. Oral medication can usually manage it.
• PDX1 (MODY4): This type affects your body’s ability to signal that it needs more insulin. It can vary in severity, with symptoms ranging from mild to severe. Treatment varies according to severity. It may include oral medications or insulin.
• HNF1B-MODY (MODY5): This type can cause other problems like kidney disease, an abnormally small pancreas and genital anomalies. You may need insulin with MODY5.

Symptoms of MODY diabetes

Symptoms of MODY are like those of other types of diabetes. Some of them are:

• Being very thirsty
• Needing to pee more often
• Losing weight unexpectedly
• Blurred vision
• Fatigue

Your exact symptoms can vary depending on what gene change causes the condition. Most of the time, the symptoms start slowly.

MODY diabetes causes

A change in just one gene causes monogenic diabetes. You inherit genes from each of your biological parents. With MODY, you inherit a gene from one or both parents that causes the disease.

Your genes provide instructions for making proteins that help your body produce insulin and regulate blood sugar. These proteins play a key role in the cells in your pancreas that release insulin. When these genes change, it makes cells in your pancreas less effective. This means your pancreas can’t produce enough insulin to manage your blood sugar.

Because MODY is inherited, it often affects multiple generations of the same family. Knowing your family history may help you get the correct diagnosis faster.

Complications

There can be complications if you don’t get the right treatment. Having high blood sugar can damage your:

• Kidneys
• Heart and arteries
• Nerves
• Eyes
• Joints

Some forms, like MODY2, usually don’t lead to complications because they’re mild forms.

How doctors diagnose MODY diabetes

Your healthcare provider diagnoses MODY diabetes based on your symptoms, age and family history. First, they’ll confirm you have diabetes with a blood sugar test.

They may suspect MODY if you:

• Are under 30
• Have a strong family history of diabetes
• Have only mildly elevated blood sugar
• Are at a healthy weight

They’ll order additional tests to confirm you have MODY and not another type of diabetes:

• Antibodies test: Providers check a sample of your blood for certain antibodies. If you have MODY, the test should be negative.
• C-peptide test: This test measures how much insulin your body makes. People with MODY still make some insulin.
• Genetic tests: These tests can detect changes to your genes. They’re the only definitive way to diagnose MODY.

How is MODY diabetes treated?

Treatment depends on what type of MODY you have. This is because each type can have different effects on your blood sugar. Options for treatment could include:

• Making changes to what you normally eat and drink
• Taking oral diabetes medication such as sulfonylureas
• Taking insulin injections or using an insulin pump

Your healthcare provider will monitor you to make sure your treatment is still working. They may need to change or adjust your treatment throughout your life. Because the condition is genetic, you’ll have it your whole life.

When should I see my healthcare provider?

Contact a healthcare provider if you have symptoms of diabetes. Be sure to share your complete health history with them, including family history.

What can I expect if I have this condition?

There’s no cure for MODY diabetes. Your provider can help you manage your blood sugar with medication and/or healthy habits. Regular checkups with your healthcare provider and blood sugar monitoring are important. This ensures your treatment plan is working.

There’s a chance you’ll pass MODY to your biological children. You may want to talk to a genetic counselor about the risk of passing MODY to your child.