• Scientists have identified specific genes that increase the risk of type 1 diabetes .
• You have a higher risk of developing type 1 diabetes if your parents or siblings have been diagnosed with the condition.
• People at high genetic risk for type 1 diabetes may be eligible for a type 1 diabetes screening test.

Type 1 diabetes is a condition where the body’s immune system mistakenly attacks and damages the cells responsible for making insulin. Insulin is a hormone that helps regulate the level of glucose (sugar) in your blood by allowing your cells to take in and use glucose for energy. People diagnosed with type 1 diabetes have higher levels of sugar in their blood, which means they need to take insulin through shots or a special pump. They also have to measure their blood sugar levels throughout the day to manage their condition properly.

Type 1 diabetes begins before you start noticing any symptoms, and it goes through three stages. In the first two stages, most people don’t experience any symptoms, and they’re usually diagnosed in the third stage.

If someone in your family is diagnosed with type 1 diabetes, it may cause worry about what this diagnosis means for other family members. Although those family members likely carry a higher risk, they will not necessarily develop type 1 diabetes. You may be surprised to know that there are screening tests and breakthrough medications for those at high risk of developing type 1 diabetes.

Keep reading to learn more about the genetic risk factors, testing, and available therapy for people at increased risk for type 1 diabetes.

Which Genetic Factors Cause Type 1 Diabetes?

Scientists have proved that certain genes are associated with the development of type 1 diabetes. These genes provide the directions for making proteins that play a crucial role in how our immune system works.

HLA Genes

The human leukocyte antigen (HLA) genes are a group of genes that help the body’s immune system understand which proteins are from the body and which are from other organisms that should be removed. Each person’s HLA system is organized in a way that is specific to that individual. In autoimmune diseases, like type 1 diabetes, the immune system gets confused and mistakes its own cells for harmful, foreign cells.

High-Risk HLA Gene Types

HLA-DRB1 comes in various forms, and this variety helps your immune system identify and respond to different types of foreign cells that shouldn’t be there. Certain versions of the HLA-DRB1 gene are associated with type 1 diabetes:

• HLA-DR3
• HLA-DR4
• HLA-DR7
• HLA-DR9

According to the American Diabetes Association (ADA), the majority of white people with type 1 diabetes have the HLA-DR3 or HLA-DR4 gene. There is less research about genetic risk factors in other racial/ethnic groups. However, the HLA-DR7 gene is suspected to be a genetic risk factor for the development of type 1 diabetes in African Americans. The ADA has also found that the HLA-DR9 gene puts Japanese people at an increased risk of type 1 diabetes.

How Do These High-Risk Genes Lead to the Development of Type 1 Diabetes?

HLA genes are inherited. People get half of their HLA genes from their mother and the other half from their father. To get type 1 diabetes, you need to inherit genetic risk factors from both parents. Still, most people who have high-risk genes don’t end up developing type 1 diabetes.

Scientists believe that high-risk genes need to be combined with other factors for type 1 diabetes to develop. These other factors are often called environmental triggers. Eating habits during childhood and certain viral infections can make you more likely to get type 1 diabetes. In a person with high-risk genes, these environmental triggers destroy the insulin-making beta cells of the pancreas leading to the development of type 1 diabetes.

Does Type 1 Diabetes Run in the Family?

Genetic diseases tend to run in families, and type 1 diabetes is no different. Specifically, having a first-degree relative with type 1 diabetes increases the risk of other family members developing it. First-degree relatives include parents and siblings.

If you’re a parent with type 1 diabetes, the risk of your child getting it depends on several factors. These factors include:

• Your sex/gender
• Your age when you developed type 1 diabetes
• How old you were when your child was born (if you are a mom with type 1 diabetes)
• Whether your partner (your child’s other parent) also has type 1 diabetes

According to the ADA, the child of a father with type 1 diabetes has a 1 in 17 (5.9 percent) chance of developing it.

For mothers with type 1 diabetes, the risk of their child developing the condition depends on how old they were when they had the baby. The risk is higher if you had your baby at a younger age. The risk is 1 in 25 (4 percent) if you had your baby before age 25. If you were older than 25 years old when you had your baby, the risk of your child having type 1 diabetes is 1 in 100 (1 percent).

Your child’s risk of developing type 1 diabetes also depends on how old you were when you were diagnosed. Being diagnosed with type 1 diabetes before turning 11 years old doubles your child’s risk.

The ADA reports that if both parents have type 1 diabetes, the child’s risk is somewhere between 10 percent and 25 percent. This is a wide range, so remember that these numbers are just estimates, and nothing is for sure.

Additionally, if one child has type 1 diabetes, their siblings’ risk of developing it ranges from 3 percent to 8 percent.

If You Have a Family Member With Type 1 Diabetes, Can You Find Out Your Risk?

Family members of people living with type 1 diabetes have a few options for determining their risk. These tests for high-risk individuals can detect the condition before you experience symptoms.

Young people whose siblings are diagnosed with type 1 diabetes are eligible for a type 1 diabetes risk test. This testing may include checking for autoantibodies, which are proteins made by the immune system that attack the body’s own cells. These proteins can attack the body’s cells, and their presence could suggest an autoimmune disease.

In type 1 diabetes, the immune system targets and destroys beta cells in the pancreas. These pancreatic beta-cells produce insulin.

The autoantibodies blood test for type 1 diabetes may look for include:

• Insulin autoantibodies (proteins produced by the immune system that interfere with the way insulin works)
• Autoantibodies to islet cells (cells in the pancreas that produce hormones)
• Antibodies against glutamic acid decarboxylase (an enzyme found in the body, including beta cells of the pancreas)

High levels of these autoantibodies may suggest that a young person is at an increased risk of type 1 diabetes. Regularly monitoring the levels of these autoantibodies in people at higher risk can help doctors pinpoint those who might benefit from steps to prevent type 1 diabetes or take action early to manage their risk.

Certain people with a family history of type 1 diabetes may also be able to take a free type 1 diabetes risk test. These free tests are done through a research study called the TrialNet Pathway to Prevention study.

Talk to your pediatrician or endocrinologist (a doctor who specializes in conditions related to your hormones) to find out if you are eligible for the autoantibodies blood test or qualify for a clinical trial.

The Benefits of Type 1 Diabetes Risk Screening

Taking a screening test can help catch type 1 diabetes early and may provide other benefits like:

• Lowering the chance of needing to go to the hospital or experiencing complications
• Helping determine if you can participate in clinical trials or studies related to type 1 diabetes
• Allowing you to develop a type 1 diabetes care plan with your doctor early
• Helping determine if you are eligible for therapy to prevent symptoms

Medication for People at Increased Risk for Type 1 Diabetes

The U.S. Food and Drug Administration (FDA) approved a medication called teplizumab-mzwv (Tzield) in November 2022. This medication can now be used to delay the start of clinical type 1 diabetes in certain high-risk individuals, especially those who already show symptoms of diabetes. Tzield is the first FDA-approved medication that can delay the progression to clinical type 1 diabetes.

Teplizumab-mzwv is for people with two or more type 1 diabetes autoantibodies and abnormal glucose levels, but no symptoms. It’s available to people 8 years of age and older.

Follow Up With Your Doctor

Talk to your doctor if you have a family history of type 1 diabetes and have any questions about type 1 diabetes risk screenings or tests. They can help determine if risk testing is right for you and your family.

Talk With Others Who Understand

On myT1Dteam, the site for people with type 1 diabetes and their loved ones, people come together to gain a new understanding of type 1 diabetes and share their stories with others who understand life with the condition.

Are you or a family member living with type 1 diabetes? Do you have experience with risk testing for type 1 diabetes? Share your thoughts in the comments below.