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What Causes Type 2 Diabetes?

Updated on October 18, 2021
Medically reviewed by
Robert Hurd, M.D.
Article written by
Kelly Crumrin

Type 2 diabetes develops when the body becomes resistant to insulin, the hormone that allows cells to take in blood glucose and use it as fuel. Without glucose, the cells begin to starve, and blood glucose levels rise, causing damage to nerves, blood vessels, and organs.

Risk Factors for Type 2 Diabetes

While researchers have established that both hereditary and environmental factors influence a person’s risk for developing type 2 diabetes, no one is certain why some people get diabetes and some people don’t. Most scientists believe diabetes is most likely caused by a combination of inherited and environmental factors.

People age 45 or older are more likely to develop type 2 diabetes than are younger people, although children and younger adults can develop the condition too. Type 2 diabetes becomes more common with age. In women who have gestational diabetes during pregnancy, there is a 50 percent risk for developing type 2 diabetes later on.

Hereditary Factors

If you have parents or siblings with type 2 diabetes, your risk for developing the condition is higher than in people with no family history of diabetes. Diabetes risk is not inherited in a clear pattern. For instance, among identical twins, if one twin develops type 2 diabetes, the other twin has a 75 percent chance of developing the condition. However, researchers have had difficulty separating genetic factors for diabetes from other family-related factors such as shared diet, sedentary habits, or genes that promote obesity.

Environmental Factors

Lifestyle factors such as obesity, diet, and lack of physical activity have a huge amount of influence over who develops type 2 diabetes. In fact, many researchers believe that obesity promotes the development of diabetes more than any other factor, accounting for as much as 80 percent to 85 percent of the risk for type 2 diabetes. Abdominal fat is thought to release chemicals that raise the level of inflammation in the body, desensitizing it to insulin. Another theory is that obesity leads to changes in the body’s metabolism, the way it makes, stores, and uses energy. These metabolic changes lead to prediabetes, which sometimes progresses to type 2 diabetes. Many obese people never develop type 2 diabetes, so genetic predisposition for diabetes may also be key in who develops the condition.

Exercise increases the body’s sensitivity to insulin and lowers blood glucose. Lack of exercise seems to promote the development of insulin resistance. Studies have proven that even modest daily exercise significantly reduces the risk for developing type 2 diabetes.

Diet can contribute to the development of type 2 diabetes. For instance, people who drink one or two cans of soft drinks each day are 26 percent more likely to develop type 2 diabetes. Beverages with similarly high sugar content can include sports or energy drinks, sweet tea, and even many fruit juices. High-calorie diets that contain large proportions of fat and carbohydrates also promote obesity, which is thought to be a leading risk factor for the development of type 2 obesity.

Condition Guide

References

  1. Risk Factors — Centers for Disease Control and Prevention
  2. Diabetes and Obesity — Diabetes.co.uk
  3. Symptoms and Causes of Diabetes — National Institute of Diabetes and Digestive and Kidney Diseases Health Information Center
  4. Diabetes — Mayo Clinic
  5. Type 2 Diabetes Causes — EndocrineWeb
  6. Family Health History and Diabetes — Centers for Disease Control and Prevention
  7. Genetics of Diabetes — American Diabetes Association
  8. Preventing Diabetes — John Muir Health
  9. Diabetes Myths — American Diabetes Association
  10. Soft Drinks and Disease — Harvard School of Public Health

All updates must be accompanied by text or a picture.
Robert Hurd, M.D. is a professor of endocrinology and health care ethics at Xavier University. Review provided by VeriMed Healthcare Network. Learn more about him here.
Kelly Crumrin is a senior editor at MyHealthTeam and leads the creation of content that educates and empowers people with chronic illnesses. Learn more about her here.

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