A person’s genes can make them more susceptible to developing type 2 diabetes. However, environmental factors such as diet and exercise can influence whether the genes express and diabetes develops.

According to the National Diabetes Statistics Report 2020, more than 34 million Americans have diabetes (about 1 in 10), and approximately 90–95% of them have type 2 diabetes.

Usually, type 2 diabetes develops in adults over 45 years old, but it is becoming more common among young adults, teens, and children.

Age, inactivity, and having obesity are risk factors of type 2 diabetes, but a person’s genes can also play a role. Type 2 diabetes has a stronger link to family history than type 1 diabetes.

Read on to learn more about the genetic link with type 2 diabetes, which genes it can involve, and how someone might be able to influence whether they develop the disease.

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The American Diabetes Association (ADA) states that type 2 diabetes has a stronger link to family history and lineage than type 1. It goes on to say that studies of twins have shown that genetics play a key role in the development of type 2 diabetes.

The ADA also advises that race can also play a role, and research indicates a higher prevalence among Asian, Black, and Latino people. But this may not be entirely due to genetics.

Learn why there is a higher prevalence of diabetes in African Americans here.

Environmental factors such as diet and lifestyle also influence the risk of developing type 2 diabetes. The ADA notes that it is possible to help prevent type 2 diabetes by exercising and reaching or maintaining a moderate weight.

There can also be a genetic role in obesity, and families often develop similar eating habits. This can put someone with a genetic predisposition at more risk for developing type 2 diabetes.

According to a 2013 review, the following genes can lead to an increased likelihood that a person will develop type 2 diabetes:

  • CAPN10: This gene encodes enzymes that degrade proteins. It was the first gene that scientists confirmed had a definitive link with type 2 diabetes.
  • TCF7L2: This protein-coding gene has the strongest links to type 2 diabetes across all racial groups.
  • ABCC8: This gene may impair the release of insulin.
  • GCGR: This gene is a glucagon receptor.
  • GCK: This is a gene for the enzyme glucokinase, which speeds up glucose metabolism and acts as a glucose sensor.
  • GLUT2: This gene encodes for a glucose transporter, which regulates the entry of glucose into pancreatic beta cells.
  • SLC2A2: This gene regulates the entry of glucose in pancreatic beta cells and triggers insulin secretion.
  • HNF4A: This regulates genes in the liver and pancreas.
  • HNF4A: This is the insulin hormone gene.
  • KCNJ11: This is the gene for the potassium channels that trigger the release of insulin.
  • LPL: This is the enzyme lipoprotein lipase, which breaks down triglycerides (fats).
  • PPARG: This gene regulates fat cell differentiation.
  • PIK3R1: This gene has a role in insulin signaling.

Environmental factors can also influence if someone will develop type 2 diabetes, and we explain this next.

Learn about the importance of genes in the human body here.

A person’s genes interact with their environment to either switch their genes off or on. This process is called epigenetics and can also play a role in the development of type 2 diabetes.

Epigenetics changes do not change the DNA sequence, but instead affect gene expression. In addition, environmental factors such as diet, exercise, and infection can result in epigenetic changes.

For example, a 2020 review indicates that dietary carbohydrates and fiber can be modifiers of some genetic variants in type 2 diabetes. Another example is smoking.

A 2013 review on the genetics of type 2 diabetes suggests the chances of inheriting the disease are as follows:

  • One parent: There is a 40% lifetime risk for someone with one parent who has type 2 diabetes.
  • Both parents: There is a 70% lifetime risk for someone who has both parents with type 2 diabetes.
  • First-degree relative: A person is three times more likely to develop type 2 diabetes if a first-degree relative has the condition. A first-degree relative is someone with whom a person shares 50% of their genes, such as a parent or full sibling.

Diet and behavioral factors can influence whether a person with a genetic predisposition to type 2 diabetes develops the disease.

Dietary factors

Keeping to a moderate weight is essential in reducing the risk of developing type 2 diabetes. But in 2013–2016, 89% of American adults whose doctors had recently diagnosed them with diabetes had overweight or obesity.

For example, a 2020 study published in The Lancet looked at the effect of an intensive lifestyle intervention on young people with early diabetes. The researchers found that a low-energy diet and physical activity led to significant weight loss and diabetes remission in over 60% of participants.

Research from the Diabetes Prevention Program shows that people with obesity may delay or help prevent diabetes by losing 5–7% of their starting weight. Individuals could try eating smaller portions, choosing foods with less fat, and avoiding sweetened drinks.

Additionally, some research indicates that antioxidants in fruits and vegetables and magnesium can lower the risk of developing the disease.

Lifestyle factors

A 2020 review outlines lifestyle factors that studies have associated with the disease and may lead to obesity, oxidative stress, and insulin resistance. A person can reduce or avoid the following to try and lower their risk for developing type 2 diabetes:

Americans can also join a National Diabetes Prevention Program to learn how to make changes to help reverse prediabetes and prevent type 2 diabetes. People can also access the ADA’s Living With Type 2 Diabetes program online.

Learn seven ways to help prevent type 2 diabetes here.

People can carry out a test to determine if they have specific genes that put them at more risk for developing type 2 diabetes. Companies such as 23andMe offer this type of test.

Genetic testing can motivate someone to make changes to their diet and lifestyle habits to help reduce their risk. People can speak to their healthcare professional to find out if genetic testing is suitable for them.

See a list of other tests for diabetes and what to expect with each one here.

Type 2 diabetes has a genetic link that can make people with a family history more at risk for developing the disease. There are several genes involved, and people can find out if they have these with genetic testing.

But because genes can change expression due to environmental factors, people can influence whether they develop type 2 diabetes with diet and lifestyle strategies.

For example, reaching or maintaining a moderate weight, being physically active, and eating a balanced diet can reduce a person’s risk. Other factors such as smoking, stress, and insomnia may also play a role in the risk of developing type 2 diabetes.

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