Epidemics and pandemics have been evolving with humans throughout history. You might have heard about the Spanish flu, H1N1 swine flu, poliomyelitis, and the most recent one, COVID-19. But do you know that there is this silent global epidemic affecting a significant portion of the global population? This epidemic is so common that we barely notice its existence. This epidemic is called diabesity. Diabesity is a combination of two closely related conditions—diabetes and obesity. How many people do you know have diabetes? How about obesity? A couple of names might come to mind.
Diabetes
Diabetes is a complex disease that negatively affects the overall health outcome of a person. In 2014, the WHO recorded 422 million cases globally, and in the U.S., 32.3 million Americans were affected in 2018. It is evident why the United Nations General Assembly declared diabetes as an international health issue in 2006. Diabetes is a chronic metabolic condition that impairs the body’s ability to turn food into energy.[1] When you eat food, that food is then broken down into sugar. The sugar is then released into the bloodstream.[2] When your blood sugar goes up, a hormone called insulin is released by the pancreas. Insulin then moves the sugar to your cells where it is stored or used.[3] If you are diagnosed with diabetes, that means your body either does not make enough insulin or cannot use the insulin effectively. If left untreated and unmanaged, it can lead to blindness, heart diseases, stroke, amputation, nerve, and organ damage.[4]
There are three different types of diabetes. Gestational diabetes occurs in women during pregnancy. This is because the body becomes less sensitive to insulin during pregnancy.[5] Type 1 diabetes is caused by an autoimmune reaction where your body stops making insulin. Approximately 5-10% of people who have diabetes have type 1 diabetes. Type 2 diabetes is caused by your body’s inability to use insulin correctly. It can still make insulin, but it cannot use it effectively. About 90-90% of people who have diabetes have type 2 diabetes. The prevalence of type 2 diabetes makes it a grave health concern especially since it affects people of all ages—from children to seniors.[6]
Obesity
According to the WHO, obesity is the “abnormal excessive fat accumulation that may impair health.”[7] In adults, body mass index (BMI) is used to classify obesity. For example, an adult with a BMI greater than or equal to 30 would be classified as obese. Children are classified differently from adults.[8]
Obesity happens because of over consuming calories than the body can burn. Over time, the extra calories add up and cause weight gain. Obesity can also be caused by genetics, aging, not getting enough sleep, and pregnancy. Health conditions like PCOS and hypothyroidism may lead to obesity.[9] Obesity causes major risks for non-communicable diseases such as cardiovascular diseases, type 2 diabetes, infertility, arthritis, and some cancers.[10]
The World Health Organization reported that the cases of obesity today are thrice as much as there were in 1975.[11] There were 1.9 million people who were overweight in 2016, and 650 million of them are already considered obese. Obesity used to be an issue in high-income countries, but today, this problem starts to affect even the middle-income, developing, and even underdeveloped countries. Obesity is common. The CDC estimated that 42.4% of American’s 20 years old and older were obese in 2017-2018.[12][13] What’s worse is more people die of obesity than being underweight.
Diabesity—Understanding the link
A modern epidemic, diabesity is the coexistence of diabetes and obesity. But how exactly does diabetes relates to obesity? Diabesity speaks about the combined health effects of diabetes and obesity.[14] Diabesity is considered the leading cause of chronic disease, strokes, dementia, and cancer. As obesity and T2D are closely linked, it is important to identify the genetic link between these two complex diseases.[15] This could help in understanding the driving factors to this epidemic. These two related conditions have a complicated relationship. Data has shown that severe obesity is a strong determinant of type 2 diabetes (T2D). Most T2D patients are also obese, which suggests a causal relationship between the two. However, when the population of obese individuals is considered, surprising statistics are revealed. Among obese people, only a small fraction develops T2D which complicates the initial causal assumptions.
Three hypotheses have been developed to explain the molecular mechanisms of diabesity:
- Inflammation Hypothesis: states that obesity represents a state of chronic inflammation. These inflammatory processes are theorized to trigger obesity-related insulin resistance and T2D.[16]
- Lipid overflow hypothesis/adipose tissue expandability hypothesis: Predicts that the “capacity for an individual to expand their fat mass store lipid is a more important determinant of obesity.”[17] This is due to the limited space of adipose tissue to store fat in a person who is obese. When the tissue reaches capacity, it overflows to other tissues like the liver and pancreas which are not equipped to store fat. As a result, the fat accumulates within the liver and pancreas, thus inhibiting insulin signals. The lipid hypothesis sees T2D as a disorder of lipid metabolism.[18]
- Adipokine Hypothesis: states how adipose cells function as an endocrine organ, which releases a variety of hormones. When fat storage increases, they “can trigger a dysfunctional release of endocrine factors.”[19] This causes metabolic damage of insulin target tissues, which results in the eventual failure of insulin-producing cells.[20]
Conclusion
Diabesity is a global health issue. It is the lead cause of strokes, chronic diseases, cancer, and dementia. It is thus important to understand how to treat it. More studies should focus on both gene-gene interactions and how genetics interact with environmental risk factors. Such studies may help with the early detection of the effects of diabesity on the body.
Reference
Chadt, A., Scherneck, S., Joost, H., & Al-Hasani, H. (2018). Molecular links between Obesity and Diabetes: “Diabesity”. In: Feingold KR, Anawalt B, Boyce A, et al., (ed). South Dartmouth (MA): MDText.com, Inc.; 2000-. https://www.ncbi.nlm.nih.gov/books/NBK279051
Centers for Disease Control and Prevention. (2020). What is diabetes? Centers for Disease Control and Prevention. https://www.cdc.gov/diabetes/basics/diabetes.html
Falck, S. (2020). An overview of diabetes types and treatments. Medical News Today. https://www.medicalnewstoday.com/articles/323627
Moores, D. (2020). Obesity. Healthline. https://www.healthline.com/health/obesity
Ng, A. C. T., Delgado, V., Borlaug, B. A., & Bax, J. J. (2021). Diabesity: the combined burden of obesity and diabetes on heart disease and the role of imaging. Nature Reviews Cardiology, 18. https://doi.org/10.1038/s41569-020-00465-5
S, U. K., Rajan, B., D, T. K., V, A. P., Abunada, T., Younes, S., Okashah, S., Ethiraj, S., C, G. P. D., & Zayed, H. (2020). Involvement of essential signaling cascades and analysis of gene networks in diabesity. Genes, 11(11). Retrieved from http://dx.doi.org/10.3390/genes11111256
Virtue, S., & Antonio Vidal-Puig, A. (2008). It’s not how fat you are, it’s what you do with it that counts. PLOS Biology, 6(9). doi: 10.1371/journal.pbio.0060237
Watson, S. (2020). Everything You Need to Know About Diabetes. Healthline. https://www.healthline.com/health/diabetes
World Health Organization. (2020). Obesity and overweight. World Health Organization. https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight
