How Do Your Genetics Affect Your Risk for Diabetes?

There are many factors that can affect your risk of developing prediabetes or diabetes — and some of them are genetic. In the U.S., more than 97 million people have prediabetes, the precursor to diabetes. But 8 out of 10 people may not even know they have it. And this is a big deal because prediabetes raises someone’s risk for Type 2 diabetes.

About 300,000 kids and 1.7 million adults in the U.S. have Type 1 diabetes. Although both Type 1 and Type 2 diabetes cause high blood sugar, the causes are different. 

So, let’s walk through the risk factors and genetics of these types of diabetes. That way, you can understand your own risk as well as what you can do about it.

Is diabetes genetic?

There are two types of diabetes: Type 1 and Type 2. Each type has different causes, but you can inherit a predisposition to either condition. Researchers are trying to understand how genetic inheritance affects someone’s risk for diabetes. They’ve found several genes connected to Type 1 and Type 2 diabetes.

But it’s still not clear how the data can be applied to measure a person’s risk. Some studies have looked at whether simply having the gene is a risk factor, or whether other risk factors are more important. Read on to learn about how your family history of diabetes affects your risk.

The genetics of prediabetes, Type 1 diabetes, and Type 2 diabetes

Let’s go through each type of diabetes to look at how family history and genetics contribute to the condition.

Prediabetes genetics

You may have prediabetes if your blood sugar levels are higher than normal, but not high enough for a diagnosis of Type 2 diabetes. The CDC’s prediabetes test can help you figure out your risk. It considers prediabetes risk factors, such as:

• Having a family history of Type 2 diabetes, especially in a parent or sibling

• Having higher body weight 

• Being over 45 years old

• Exercising less than 3 times a week

• Giving birth to a baby weighing more than 9 lbs

• Having gestational diabetes (diabetes while pregnant) or polycystic ovary syndrome (PCOS) 

• Being part of a certain racial and ethnic group (including being African American, Hispanic/Latino, American Indian, Pacific Islander, and Asian American)

Ultimately, understanding your risk for prediabetes is similar to understanding your risk for Type 2 diabetes. This is because prediabetes is a precursor to Type 2 diabetes. So, let’s explore the genetics behind Type 2 diabetes a little more closely.

EXPERT PICKS: WHAT TO READ NEXT

• Type 1 vs. Type 2 diabetes: Most people with diabetes have Type 2 diabetes. Learn the key differences between Type 1 and Type 2 diabetes.

• You can reverse prediabetes. There are steps you can take to help prevent Type 2 diabetes from developing, if you have high blood sugar.

• Preventing long-term complications: If you have diabetes, managing your blood sugar levels can help prevent more health issues down the road.

Type 2 diabetes genetics

Someone with Type 2 diabetes has high blood sugar because their body doesn’t make enough insulin, or it can’t use the insulin properly. The risk factors for Type 2 diabetes are similar to those for developing prediabetes:

• Family history of diabetes

• Greater body weight

• Age over 45 years

• Non-alcoholic fatty liver disease (NAFLD)

• Racial and ethnic group (as above)

But it may surprise you to learn that genetics play a stronger role in Type 2 diabetes than Type 1. Researchers often use identical twin studies to understand genetic risk factors. This is because identical twins share the same genes but often have different lifestyles. Research shows that if one twin has Type 2 diabetes, the other twin has a 75% chance of also developing it. This suggests there’s a large genetic component — but that genes aren’t the whole story.

At this time, it’s unclear whether genetic predisposition alone can lead to Type 2 diabetes later in life. You may inherit a genetic predisposition from your family, but you may also share dietary or lifestyle habits that raise your risk of developing diabetes. This contributes to the idea that diabetes “runs” in families who share both genetics and lifestyle.

Type 1 diabetes genetics

Type 1 diabetes is less common. Less than 10% of all people with diabetes have Type 1. It’s one of many autoimmune diseases that are often linked to specific genes (HLA-DR3 or HLA-DR4), which are more common in white people. But it seems to be more complicated than that.

Researchers use identical twin studies to study Type 1 diabetes, just like they do with Type 2. If one twin develops Type 1 diabetes, the other only has a 25% to 50% chance of also developing it. This means that there’s a hereditary factor, but it isn’t the only driver. In most cases of Type 1 diabetes, people need to inherit risk factors from both parents plus have environmental factors that contribute to the development of the disease.

Studies have evaluated several possibilities in terms of environmental risk factors. These include:

• Cow’s milk

• Breastmilk

• Vitamin D deficiency

• Gluten

The evidence has been mixed so far, but it does suggest that certain viral infections could play a role. Research is ongoing.

Monogenetic diabetes

Monogenetic diabetes is a rare type of diabetes due to a single gene change. It affects the way the pancreas (where insulin is made) forms or works, leading to diabetes. Genetic counseling is an option for someone with monogenetic diabetes to determine if it could be passed on.

Is diabetes more likely to be inherited from the mother or father?

How likely you are to pass on Type 1 diabetes genetically depends on your sex and age:

• If you’re genetically male and have Type 1 diabetes, the odds of your child developing diabetes are 1 in 17. 

• If you’re genetically female and have Type 1 diabetes, your child’s risk of developing diabetes is less. It also depends on your age when you become pregnant. 

• If you’re younger than 25 during pregnancy, the risk is 1 in 25. 

• If you’re older than 25, the risk is 1 in 100.

More research is needed to figure out the exact risks for those with Type 2 diabetes. 

Can you prevent diabetes, even if your genes put you at risk?

Yes, the good news is that prediabetes is reversible with lifestyle changes. And specific lifestyle changes can help lower your risk of developing prediabetes and Type 2 diabetes. 

Recommended changes include the following:

• Adding healthy food choices into your diet

• Maintaining a healthy weight for your body

• Starting a regular exercise routine

• Quitting smoking

Ask your healthcare team for help or guidance when you need it.

If you’re at risk for or have prediabetes or diabetes, it can be easy to feel scared or overwhelmed. But remember that you can take action to keep yourself healthy and lower your risk of developing diabetes or diabetes complications. It all starts with one step.

Currently, there’s not a way to prevent Type 1 diabetes. But researchers are working on ways to catch it in early stages (before it causes symptoms) and prevent its progression. 

When should you get screened for diabetes?

Testing for diabetes usually involves one or more of a handful of tests that can diagnose Type 2 diabetes. The American Diabetes Association (ADA) recommends screening for:

• All adults age 35 years and older, regardless of risk factors

• Any adult with a BMI of 25 or higher and at least one risk factor for diabetes

Some people with a family history of Type 1 diabetes may be eligible for a screening test. Your primary care provider can discuss your options or refer you to a specialist for further testing, if needed.

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Written by:

Nicole Andonian, MD

Nicole Andonian, MD, is a private practice anesthesiologist in Orange County, California. Her focus is in general anesthesia, regional anesthesia, and acute pain management.

Edited by:

Sophie Vergnaud, MD

Sophie Vergnaud, MD, is the Senior Medical Director for GoodRx Health. A pulmonologist and hospitalist, she practiced and taught clinical medicine at hospitals in London for a decade before entering a career in health education and technology.

Reviewed by:

Farah Naz Khan, MD

Farah Naz Khan, MD, is a board-certified physician at the UW Medicine Diabetes Institute and a clinical assistant professor of metabolism, endocrinology, and nutrition at the University of Washington.

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