Man with diabetes checking glucose while wondering how obesity causes diabetes

How Does Obesity Cause Diabetes?

Written on June 27, 2023 by Sendra Yang, PharmD, MBA. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

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Having extra weight is a challenge for many people. In the United States, nearly 1 in 3 adults are overweight, and about 42% are obese.[1] Not only is obesity common, but it is also a very expensive disease for society. In the U.S., the annual medical cost of obesity is estimated to be close to $173 billion in 2019.[2,3] The productivity costs related to absenteeism due to obesity are between $3.38 billion and $6.38 billion annually.[3] Furthermore, annual medical expenses for adults with obesity are around $1,800 higher than costs for people at a healthy weight.[2]

Obesity is a complex, serious chronic disease that occurs when your weight is greater than normal based on your height.[2-4] A common comorbidity of obesity is type 2 diabetes.[3] To understand the connection between obesity and diabetes, and specifically how obesity causes diabetes, let’s initially discuss the causes and other health concerns of obesity, followed by what diabetes is.

Obesity Causes and Associated Health Concerns

Various factors can impact excess weight gain, including an unhealthy diet, limited physical activities, and abnormal sleep habits.[1,4] Your genetics and medications can also influence your weight. Social determinants of health or conditions where we “live, learn, work, and play” is another factor that contributes to weight gain.[1,4,5] Access to healthy food choices and safe recreational areas for exercise are examples of social determinants of health.[1,5]

Many health issues are associated with being overweight and obese.[1,3] The risk of the following medical conditions is increased with adult obesity[3]:

  • High blood pressure or hypertension
  • Elevated cholesterol
  • Heart disease and stroke
  • Asthma
  • Sleep apnea
  • Osteoarthritis and musculoskeletal disorders
  • Gallstones and gallbladder disease
  • Certain types of cancers
  • Depression and anxiety
  • Type 2 diabetes

What is Diabetes?

Diabetes is a chronic condition that results in higher-than-normal blood sugar levels.[6] There are three main types of diabetes: type 1, type 2, and gestational. Gestational diabetes occurs during pregnancy in women with no previous history of diabetes and typically disappears after delivery. Type 1 diabetes is an autoimmune disease where your body no longer makes insulin. The primary treatment for type 1 diabetes is to take insulin injections. Type 2 diabetes is the most common type, and up to an estimated 95% of people with diabetes have type 2.[6,7] Type 2 diabetes is caused by insulin resistance and insufficient insulin production.[7,9,10] Insulin resistance is when your cells no longer respond to insulin, leaving too much blood sugar in your bloodstream. Having prediabetes, being overweight, being age 45 years or more, having a family member (parent, brother, or sister) with type 2, physical inactivity, and a history of gestational diabetes are all risk factors for type 2 diabetes.[8]

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How Does Obesity Cause Diabetes?

Being overweight and obese is a significant risk factor for type 2 diabetes.[8-11] An increase in body mass index or weight is directly proportional to the risk of developing type 2 diabetes.[9,10] Excess body fat prompts metabolic irregularities, including insulin resistance, beta cell dysfunction, and other abnormalities.[9] The exact mechanisms of how obesity causes diabetes are not completely clear, but it is proposed that obesity impacts insulin and beta cell function.[9-11]

Insulin is a hormone that facilitates the uptake of glucose from the bloodstream into cells.[11] Insulin resistance is a critical factor in obesity causing type 2 diabetes.[9-11] Increased fat tissue contributes to insulin resistance because of: inadequate oxygen delivery and increased fat cell oxygen demand, an increase in proinflammatory immune cells, a decrease in the insulin-sensitizing hormone, an increase of free fatty acids into body circulation, and alterations to specific microRNAs derived from adipose tissue macrophages. [9,10]

Beta cells in the pancreas function to produce and secrete insulin.[9] In obese people who do not have type 2 diabetes, the rate of insulin secretion by the beta cells is higher than in lean people.[9-11] The increased secretion rate is able to produce enough insulin to compensate for insulin resistance and normalize the blood sugar concentration level. Over time, the function of the beta cells declines, causing a decrease in glucose control, leading to type 2 diabetes. Additionally, it is proposed that the increased plasma-free fatty acids in the body contribute to causing beta cell dysfunction and death.

Weight Loss in Obesity and Type 2 Diabetes

One of the best ways to improve your overall health if you are obese, have type 2 diabetes, or both is to lose weight.[12] Losing only 5% to 10% of your total body weight can improve your blood glucose levels. Combining a healthy diet with increased exercise can help you lose weight. But having a healthy sleep routine and finding your motivation to lose weight is also important.

Telehealth via Everlywell

Through the Everlywell online weight management program, you can meet with a licensed healthcare provider virtually to discuss your weight loss goals and comorbid conditions. Through the Weight Care+ program, you can schedule one-on-one regular virtual visits with a certified clinician who can help you develop a plan to achieve your health goals.

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  1. Overweight & Obesity Statistics. National Institute of Diabetes and Digestive and Kidney Diseases. Accessed June 14, 2023.
  2. Adult obesity facts. Centers for Disease Control and Prevention. May 17, 2022. Accessed June 14, 2023.
  3. Consequences of obesity. Centers for Disease Control and Prevention. July 15, 2022. Accessed June 14, 2023.
  4. Causes of obesity. Centers for Disease Control and Prevention. March 21, 2022. Accessed June 14, 2023.
  5. Obesity Basics. Centers for Disease Control and Prevention. June 3, 2022. Accessed June 14, 2023.
  6. What is diabetes? Centers for Disease Control and Prevention. April 24, 2023. Accessed June 13, 2023.
  7. Type 2 diabetes. Centers for Disease Control and Prevention. April 18, 2023. Accessed June 14, 2023.
  8. Diabetes risk factors. Centers for Disease Control and Prevention. April 5, 2022. Accessed June 14, 2023.
  9. Klein S, Gastaldelli A, Yki-Järvinen H, Scherer PE. Why does obesity cause diabetes? Cell Metab. 2022;34(1):11-20. doi: 10.1016/j.cmet.2021.12.012
  10. Al-Goblan AS, Al-Alfi MA, Khan MZ. Mechanism linking diabetes mellitus and obesity. Diabetes Metab Syndr Obes. 2014;7:587-91. doi: 10.2147/DMSO.S67400
  11. Wondmkun YT. Obesity, Insulin Resistance, and Type 2 Diabetes: Associations and Therapeutic Implications. Diabetes Metab Syndr Obes. 2020;13:3611-3616. doi: 10.2147/DMSO.S275898
  12. Healthy weight. Centers for Disease Control and Prevention. December 30, 2022. Accessed June 13, 2023.
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