Written by Jasmine Lobo, Edited by Emily Begnel, MPH; Edited by Courtney Coleman
Introduction
There are approximately 462 million people living with type II diabetes worldwide, which is about 6% of the world’s population (1). Because type II diabetes is so common, it substantially contributes to morbidity and mortality, and it is estimated to be the ninth most common cause of death worldwide (1). In the United States, 37 million people have diabetes, and 90% of these cases are type II diabetes (2). Type II diabetes is also associated with an increased risk of other chronic conditions, including heart disease, high blood pressure, neuropathy, damage to the eyes, and kidney disease (3).
Causes
Type II diabetes is caused by the body becoming resistant to insulin, a hormone that helps regulate blood sugar levels. Glucose is a sugar that is the cell’s main source of energy. In people without diabetes, insulin facilitates the entry of glucose into the cell from the bloodstream, reducing blood sugar levels back to normal levels(3). Although the exact cause of insulin resistance is unknown, genes that are linked to the development of insulin resistance have been identified. Excess body fat and physical inactivity may also contribute to insulin resistance(4). When cells are less responsive to insulin in type II diabetes, there is a buildup of glucose in the bloodstream, and not enough insulin can be produced by the pancreas to keep up with rising glucose levels (5).
Symptoms and Risk Factors
The following symptoms are the most common symptoms of type II diabetes: increased thirst, frequent urination, increased hunger, unintended weight loss, fatigue, blurred vision, slow-healing sores, frequent infections, numbness or tingling in the hands or feet, and areas of darkened skin in the armpits and neck (3).
There are many factors that can contribute to the development of type II diabetes, including lifestyle, environmental, and genetic factors. Obesity and physical inactivity are linked to insulin resistance (6). Examples of environmental factors that can contribute to physical inactivity and obesity are living in cities that are not walkable, or that have limited access to supermarkets, which can make people more dependent on unhealthy foods from convenience stores or fast food restaurants (7). In addition, risk for type II diabetes increases with age (3).
Treatment and Prevention
Without management of glucose levels in the bloodstream, type II diabetes can increase the risk for many comorbidities, such as heart disease, kidney disease, and dementia (3). Treatment for type II diabetes often focuses on adjustments to behavior and lifestyle, such as increased exercise and reduction of excess fat. Dietary changes often include avoiding highly processed carbohydrates and artificial sweeteners, consuming unsaturated fats instead of trans fats, and decreasing consumption of red meat (8). These lifestyle changes can help to increase sensitivity to insulin, and in turn, lower blood glucose levels (4). People living with type II diabetes are also commonly prescribed medication that decreases their blood glucose levels. Some people with type II diabetes need to take insulin if other treatments do not help to sufficiently decrease blood glucose levels (9).
Type II diabetes can be prevented through proactive lifestyle changes similar to those used for treatment, such as exercise and dietary changes. Other preventative measures are to stop smoking and reduce alcohol consumption, as these are also risk factors for type II diabetes (8).
Works Cited
Khan MA, Hashim M, King J, Govender RD, Mustafa H, Kaabi JA. Epidemiology of Type 2 Diabetes – Global burden of disease and Forecasted Trends. Journal of Epidemiology and Global Health. 2020;10(1):107. doi:10.2991/jegh.k.191028.001
Type 2 Diabetes. Centers for Disease Control and Prevention. https://www.cdc.gov/diabetes/basics/type2.html. Published April 18, 2023. Accessed October 24, 2023.
Type 2 diabetes - Symptoms and causes - Mayo Clinic. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/type-2-diabetes/symptoms-causes/syc-20351193#:~:text=Diabetes%20is%20associated%20with%20an,can%20damage%20or%20destroy%20nerves. Published March 14, 2023. Accessed October 24, 2023.
Professional CCM. Insulin resistance. Cleveland Clinic. https://my.clevelandclinic.org/health/diseases/22206-insulin-resistance. Published December 16, 2021. Accessed November 23, 2023.
The Insulin Resistance–Diabetes connection. Centers for Disease Control and Prevention. https://www.cdc.gov/diabetes/basics/insulin-resistance.html. Published June 20, 2022. Accessed October 24, 2023. (4 → 5)
Insulin Resistance & Prediabetes. National Institute of Diabetes and Digestive and Kidney Diseases. https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes/prediabetes-insulin-resistance#insulinresistance. Published June 7, 2023. Accessed October 24, 2023. (5 → 6)
Dendup T, Feng X, Clingan S, Astell-Burt T. Environmental risk factors for developing Type 2 diabetes mellitus: a systematic review. International Journal of Environmental Research and Public Health. 2018;15(1):78. doi:10.3390/ijerph15010078
Simple steps to preventing diabetes. The Nutrition Source. https://www.hsph.harvard.edu/nutritionsource/disease-prevention/diabetes-prevention/preventing-diabetes-full-story/. Published March 2, 2021. Accessed October 24, 2023. (7 → 8)
Type 2 diabetes. Johns Hopkins Medicine. https://www.hopkinsmedicine.org/health/conditions-and-diseases/diabetes/type-2-diabetes. Published June 24, 2022. Accessed October 24, 2023. (6 → 9)
This post is not a substitute for professional advice. If you believe that you may be experiencing a medical emergency, please contact your primary care physician, or go to the nearest Emergency Room. Results from ongoing research is constantly evolving. This post contains information that was last updated on March 14, 2024.
Jasmine Lobo is a second year majoring in public health at UC Berkeley.
Emily Begnel, MPH is a third year PhD candidate in epidemiology at the University of Washington in Seattle, where she also completed her MPH in 2017.
Courtney Coleman is a master's degree candidate in biology at Harvard and Co-President of Students vs Pandemics.