Monogenic diabetes is a rare type of diabetes caused by a change or mutation to a single gene. It differs from type 1 or type 2 diabetes, and often requires genetic testing for an accurate diagnosis.

In monogenic diabetes, insulin production is reduced. This causes glucose (blood sugar) levels to rise. But not all cases of monogenic diabetes require insulin treatment.

There are two main forms of monogenic diabetes:

  • neonatal diabetes mellitus (NDM) occurs in newborns and infants
  • maturity-onset diabetes of the young (MODY) is more common than NDM, and occurs in adolescents and young adults

While monogenic diabetes is a form of diabetes, it does differ from types 1 and 2, which are polygenic. Monogenic diabetes stems from a mutation or change in a single gene. Polygenic types result from mutations to multiple genes.

All cases of type 1 diabetes require insulin treatment, while type 2 diabetes and monogenic diabetes do not always require insulin. Insulin treatment is more likely to be needed as people with monogenic diabetes get older.

Monogenic diabetes is caused by changes or mutations in a single gene. Monogenic types of diabetes are often inherited from just one parent, called an “autosomal dominant” gene. Sometimes the mutation or change happens spontaneously, which means it’s not inherited.

While some types of monogenic diabetes may be temporary, it can sometimes also be a lifelong condition.

Symptoms of monogenic diabetes can vary, depending on which kind it is. Knowing how to recognize possible symptoms of MODY or NDM, especially in a young child, can help you get timely, appropriate treatment.

SymptomsNeonatal diabetes mellitus (NDM)Maturity-onset diabetes of the young (MODY)
frequent urination
rapid breathing
dehydration
thirst
blurry vision
recurrent skin infections
recurrent yeast infections

Blood sugar tests and genetic testing are used to diagnose monogenic diabetes like MODY and NDM. Genetic testing can be done on blood or saliva samples. The DNA is examined for changes in the genes that cause monogenic diabetes.

The National Institutes of Health explains that genetic testing for monogenic diabetes is recommended if:

  • diabetes is diagnosed before 6 months of age
  • diabetes is diagnosed in children or young adults, especially those with a family history of diabetes, or those who don’t have typical features of type 1 or 2
  • there is stable and mild fasting hyperglycemia, especially without obesity

There are at least 14 different genes associated with MODY, and more are still being discovered and researched. The type of gene detected can indicate MODY’s severity or mildness.

The tests are most commonly used to detect the following genes:

  • HNF1A gene (MODY 3)
  • glucokinase gene or GCK (MODY 2)
  • HNF4A gene (MODY 1)
  • HNF1B gene (MODY 5)

For those with MODY, other clinical tests can be used in addition to genetic testing. Per a 2020 overview of clinical screening approaches for MODY, these may include:

  • testing antibodies for type 1 diabetes such as anti-GAD antibodies, or zinc transporter antibodies (which are low in people with MODY)
  • checking the C-peptide level (which indicates whether the body makes insulin)

If a newborn or a baby starts having symptoms of diabetes, it’s often recommended to test for monogenic diabetes. It’s rare for type 1 diabetes to occur in infants, and type 2 diabetes can affect older kids, not babies. NDM could be missed or misdiagnosed without genetic testing.

Treatment depends on the genetic mutation causing monogenic diabetes, and the severity of the condition or type.

Some forms of monogenic diabetes can be managed with diet and exercise, while others require insulin. Treatment with an oral medication called a sulfonylurea agent may also be necessary. Sulfonylurea is an oral medicine that helps the body release more insulin into the blood.

If you notice symptoms of diabetes or monogenic diabetes in your baby, child, or teen, call your doctor. This is especially true if there is a family history of diabetes or monogenic diabetes.

Talk with your doctor about risk factors and what to look out for. You may be referred to a pediatric endocrinologist, a doctor who specializes in diagnosing and treating hormone problems in young people, including diabetes.

Monogenic diabetes is a form of diabetes caused by a single gene mutation rather than multiple. Monogenic diabetes may be managed differently than the more common polygenic types 1 and 2 and doesn’t always require insulin treatment.

Monogenic diabetes is treatable, but an accurate diagnosis is essential to getting the proper care. Knowing your family medical history of diabetes and getting genetic testing done can help confirm the presence of this condition. Knowing what symptoms to watch out for, especially in infants and young adults, can also help identify and treat monogenic diabetes as soon as possible.

Research into this rare type of diabetes is ongoing. Your healthcare team will work with you to figure out the best plan for your sub-type of monogenic diabetes.