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Maturity-onset diabetes of the young (MODY) is a type of diabetes that runs in families. It’s different from type 1 and type 2 diabetes. The name comes from the fact that it looks like adult forms of diabetes, but develops in young people.
Unlike other types of diabetes, MODY is caused by a mutation (change) in a single gene. Since this change can only be found through detailed testing and the symptoms can look like other types of diabetes, it’s often misdiagnosed. Getting the right diagnosis of MODY is important for getting the right treatment.
Read on to learn the key facts about MODY, including how it’s passed down through families, what the symptoms are, and how doctors can tell it apart from other types of diabetes.
MODY includes several inherited forms of diabetes. This means it can be passed down from parent to child. MODY is a rare form of diabetes. Less than 5 percent of people with diabetes have MODY.
If someone in your family has MODY, you may be more likely to get it. MODY often appears across generations — like in a grandparent, parent, and child. Family history is also a risk factor for type 2 diabetes, but MODY is different because it’s caused by a single genetic mutation.
Most of the time, the mutation is passed down in what’s called an autosomal dominant pattern. This means only one parent needs to have the genetic mutation for it to be passed down to their child. If a parent has the mutation, each of their children has a 50 percent chance of getting it.
MODY is most often found in adolescents and young adults, but it can be diagnosed at any age. MODY usually starts between the ages of 10 and 40, and often before age 30.
Symptoms of MODY tend to develop slowly. Many people with MODY might live with high blood sugar for several years without noticing symptoms. Because of this, MODY may go undiagnosed for a long time. MODY symptoms often look like those of other types of diabetes, like type 1 and type 2.
Symptoms of MODY include:
Frequent yeast infections, skin infections, and blurry vision may be early symptoms of MODY, if symptoms appear at all.
The symptoms of MODY are caused by high blood sugar levels. High blood sugar levels in people with MODY happen because the body doesn’t make enough insulin.
MODY is caused by a gene mutation that leads to problems with insulin production. With MODY, the cells that make insulin in the pancreas don’t work properly. As a result, not enough insulin is released from the pancreas, especially after eating. Without enough insulin, blood sugar levels stay too high.
People with type 1 diabetes also don’t make enough insulin. But in type 1 diabetes, the immune system attacks cells in the pancreas. In MODY, the pancreas is not destroyed, but insulin production is reduced and secretion is impaired.
Because symptoms of MODY can look similar to other types of diabetes, misdiagnosis is common. As many as 80 percent of people with MODY are misdiagnosed as having type 1 or type 2 diabetes. This matters because MODY may need different treatment than other types of diabetes.
A blood sugar test is usually the first step in figuring out if someone has MODY. Doctors may also test for certain antibodies found in type 1 diabetes. These antibodies are not present in MODY. Insulin resistance can also be a sign of MODY in people with MODY and obesity, but it’s also a common sign of type 2 diabetes in people with obesity. Someone diagnosed with type 2 diabetes may have MODY. Signs that this might be the case include:
Having a family member with MODY is often the biggest clue that someone has MODY. To be sure that someone has MODY and not a different type of diabetes, doctors may need to order a genetic test. A genetic test can confirm whether someone has MODY and also show the type of MODY they have. However, genetic testing can be expensive and take time. Doctors may try other tests first to decide whether genetic testing is needed.
Different types of MODY are caused by mutations in different genes. The different types of MODY are categorized by the genetic mutation that causes it.
So far, at least 14 genetic mutations have been linked to MODY. The most common types of MODY, listed from most to least common, involve changes in these genes:
MODY 1, MODY 2, and MODY 3 make up about 95 percent of all MODY cases. People who inherit these genetic mutations have a higher risk of developing MODY. For example, about 95 percent of people with the MODY 3 mutation develop diabetes, usually by age 25.
Just like with type 2 diabetes, MODY can lead to complications. In MODY 1 and MODY 3, having uncontrolled high blood sugar levels can cause problems in the eyes and kidneys over time.
A diabetes-related problem in the eyes is called diabetic retinopathy. It can eventually lead to vision loss. Kidney damage from diabetes is called diabetic nephropathy and can lead to kidney failure and end-stage renal disease.
People with MODY 3 may also be more likely to develop noncancerous liver tumors.
MODY 5 may cause both diabetes symptoms and kidney and urinary tract abnormalities, such as kidney cysts. People with MODY 5 may also have problems unrelated to diabetes, such as liver abnormalities or gout. Complications from MODY 2 are very rare.
MODY is a chronic condition, meaning it is lifelong. Because it’s inherited, it can’t be prevented. But healthy lifestyle habits can help people with MODY delay symptoms. For example, staying at a healthy weight, out of the obesity range, through diet and exercise, can help prevent or delay the need for medication.
Treatment will depend on the type of MODY someone has. Some types of MODY are treated with insulin injections and pills, while other forms of MODY may not need treatment at all.
The main treatment for MODY 1 and 3, for example, is lifestyle changes, like eating a low-carbohydrate diet. These types of MODY involve problems with how the body handles glucose, the sugar that comes from carbohydrates. Lifestyle changes are usually the first step, similar to treatment for type 2 diabetes. If blood sugar levels stay high, doctors may prescribe sulfonylureas, a type of oral medicine that helps the body make more insulin.
People with MODY 2 usually don’t need treatment because the risk of complications is very low. In most cases, people with MODY 2 don’t have symptoms. However, if a person with MODY 2 is pregnant, treatment may be needed during pregnancy to protect the baby.
If you have questions about MODY, talk to your healthcare provider. Because MODY is often misdiagnosed, learning how it differs from other types of diabetes can help. If you or someone you know has a family history of MODY, it can be especially helpful to know the signs and talk to a doctor if you’re concerned.
On DiabetesTeam, the social network for people with diabetes and their loved ones, members come together to ask questions, give advice, and share their stories with others who understand life with diabetes.
Do you have experience with MODY? Was MODY ever part of your diabetes diagnosis? Share your comments below, or start a conversation by posting on your Activities page.
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