China: The Not-So-Sweet Rise of Type II Diabetes

BY MICHAEL MARCEL

In 1987, KFC brought its signature fried chicken to Beijing, becoming the first Western fast food chain to open its doors in Mainland China. By 2011, the number of KFCs in China had grown to over 3,000 across 650 cities, with one new restaurant opened per day.¹ McDonalds, Pizza Hut, and other American fast food joints are now ubiquitous in many Chinese cities and are one of the many signs of the rapid economic development that has occurred over the past several decades. However, recent changes in diet and lifestyle have also brought about a sharp increase in the prevalence of many chronic diseases. As the country with the world’s largest population (over 1.3 billion), such changes have serious financial and structural implications.

The meteoric rise in the prevalence of type II diabetes in China is particularly striking. While only 1% of the population was reported to have type II diabetes in 1980, the prevalence rose to 11.6% as of 2010; China now has the largest number of individuals with diabetes in the world.² Alarmingly, 50.1% of the population is estimated to have prediabetes – a veritable ticking-time bomb without intervention.² Over the course of China’s transition from a centrally planned economy to a market economy, the country has had extraordinary successes in health system reforms, especially in the fields of infectious disease, child and maternal mortality, and infrastructure. However, efforts to curb the rise of diabetes and other non-communicable diseases have been relatively slow. Alarmingly, representative samples suggest only 30.1% of those with diabetes are diagnosed and are aware that they have the disease.³ Furthermore, while type II diabetes continues to affect the growing elderly population, it is increasingly affecting young people and marginalized groups, which will undoubtedly be detrimental to quality of life, productivity, and health-care systems. Costs associated with diabetes are projected to reach 360 billion RMB (almost 60 billion USD) by 2030.⁴

Type II diabetes is a metabolic disorder characterized by hyperglycemia, or high blood sugar levels, and insulin resistance, as well as relatively lower levels of insulin production. Normally, beta-cells in the pancreas produce the hormone insulin in response to higher than normal levels of blood sugar right after a meal. Insulin is dual-purposed, it not only maintains blood sugar levels within a non-toxic range, but also allows cells to metabolize glucose for energy production. However, in patients with type II diabetes, this system does not function harmoniously. In most patients, insulin resistance first develops before the onset of type II diabetes and is strongly linked to obesity. Insulin resistance is a physiological condition in which the cells in the body become less sensitive to the action of insulin, therefore reducing the blood glucose lowering effects of insulin, and forcing the pancreas to produce more and more insulin in an effort to reduce high blood sugar levels. Insulin resistance transitions into type II diabetes when beta-cell dysfunction also occurs, which means that these pancreatic cells can no longer produce enough insulin to compensate for the high levels of blood sugar. Type II diabetes can cause a number of complications over a person’s lifetime, including increased risk of cardiovascular disease, lower limb amputation, blindness, dementia, and frequent infections, as well as higher rates of hospitalization.^{5, 6, 7} Typically, type II diabetes is associated with a ten-year-shorter life expectancy.⁵

China’s economic transition has created what many call an “obesogenic environment,”⁸ in which rapidly changing lifestyle habits manifest themselves in weight gain and disease, such as type II diabetes. Prevailing theories on the creation of an obesogenic environment highlight how the mismatch between human biology and societal modernization can have negative consequences for human health. As the story goes, humans evolved in a physically strenuous world where food was scarce and pathogens were prevalent; as such, our genes and traits have optimized efficient energy storage and swift stress and inflammatory responses. However, in modernizing societies characterized by food abundance, psychosocial stress, and physical inactivity, these genetic features may actually put us at risk of diabetes, obesity, and other chronic illnesses.⁹ China’s economic boom and assimilation to western culture over the past several decades seem to follow this story. While traditionally, the Chinese lifestyle involved arduous physical activity and a low-calorie diet rich in carbohydrates and low in animal fat, globalization after economic reform in 1978 has led to increased consumption of sugar-sweetened beverages, animal products, and high-fat foods.¹⁰ However, east-west exchange is far from the only cause: high rates of tobacco use, increased consumption of refined rice and salt in recent decades, and increased use of cars associated with urbanization and modern lifestyle have also contributed to the creation of an obesogenic environment in many areas of China.¹⁰ Interestingly, the average daily caloric intake has not changed in past decades, implicating physical inactivity and dietary changes as the main drivers of obesity.¹¹ The prevalence of overweight and obesity increased by 4.1 times in China from 1982 to 2002, and these statistics are only continuing to increase.^{12, 13}

While the broader societal trends fueling the diabetes epidemic in China seem to resemble the narrative in other rapidly modernizing countries, the pathophysiology of type II diabetes in Chinese and other East Asian populations is also of interest. A nationwide study in China concluded that the Chinese population is especially susceptible to type II diabetes, developing the disease at a considerably lower BMI than European populations.¹⁴ This means that while, on average, most Westerners developing diabetes are overweight or obese, most Chinese people developing type II diabetes are actually considered to be normal weight. This increased risk of diabetes at lower BMI has been partly attributed to the fact that East Asian populations, including the Chinese, have a tendency to accumulate fat viscerally, or in the abdominal region, compared to other ethnic groups.¹⁵

However, the biological intricacies of type II diabetes in the Chinese population do not stop there; the pathological conditions that lead to type II diabetes in the Chinese population are also distinct from those seen in other ethnic populations. In type II diabetes patients, the proportion of insulin resistance versus beta-cell dysfunction causing the disease differs. This means that some patients have insulin resistance and only a slight defect in beta-cell insulin production, while others have minor insulin resistance and beta-cell dysfunction is the main driver of their disease. In most westerners, insulin resistance is the initial and primary cause of type II diabetes. However, compared to other ethnic populations, Chinese patients have worse beta-cell deterioration in the early stages of their disease.¹⁵

Considering these unique trends and the nature of the type II diabetes epidemic in China, it is important that strategies to prevent, manage, and treat this disease are not taken directly from other countries– in other words, China must write its own prescription in its fight against diabetes. The Chinese Ministry of Health has already made efforts to address this escalating public health crisis. In 2012, the China National Plan for Non-Communicable Disease Prevention and Treatment (2012-15) was formulated, proposing a long-term strategy to use public measures, inter-sector collaboration, and social participation to promote a healthier environment, integrate prevention with treatment, and reform the healthcare system. Initiatives targeted specifically at diabetes might include identifying and reaching out to high-risk individuals (prediabetics), and promoting self-management through education and support, with a specific eye toward maximizing the potential of new technologies that can allow for greater doctor-patient interaction and communication between healthcare providers.¹⁶ In the meantime, more research will be needed to understand the specific risk factors affecting Chinese populations in order to create the optimal policy approach.

Michael Marcel is a senior in Ezra Stiles College majoring in Molecular, Cellular, and Developmental Biology. He can be contacted at michael.marcel@yale.edu.

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References

1. Starvish, M. (2011). KFC’s explosive growth in China. HBS Working Knowledge. Retrieved from http://hbswk.hbs.edu/item/6704.html.
2. Diabetes in China: mapping the road ahead. (2014). The Lancet Diabetes & Endocrinology, 2(12), 923. Retrieved from http://dx.doi.org/10.1016/S2213-8587(14)70189-5.
3.  Xu, Y., Wang, L., He, J., Bi, Y., Wang, T. Jiang, Y., … & Ning, G. (2013). Prevalence and control of diabetes in Chinese adults. JAMA, 310(9), 948-59. Retrieved from http://dx.doi.org/10.1001/jama.2013.168118.
4. Wang, W., McGreevey, W.P., Fu, C., Zhan, S., Luan, R., Chen, W., & Xu, B. (2009). Type 2 diabetes mellitus in China: a preventable economic burden. American Journal Management Care, 15(9), 593–601.
5.  Melmed, S., Polonsky, K.S., Larsen, P.R., & Kronenberg, H.M. (2011). Williams textbook of endocrinology (12th ed.). Philadelphia: Elsevier/Saunders, 1371–1435.
6. Pasquier, F. (2010). Diabetes and cognitive impairment: how to evaluate the cognitive status? Diabetes & Metabolism, 36(Suppl 3: S100–5). Retrieved from http://dx.doi.org/ 10.1016/S1262-3636(10)70475-4.
7. Ripsin C.M., Kang H., & Urban R.J. (2009). Management of blood glucose in type 2 diabetes mellitus. American Family Physician, 79(1), 29–36.
8. Chan, J.C.N., Zhang, Y., & Ning, G. (2014). Diabetes in China: a societal solution for a personal challenge. The Lancet Diabetes & Endocrinology, 2(12), 969-979. Retrieved from http://dx.doi.org/10.1016/S2213-8587(14)70144-5.
9. Ji, C.Y., & Tsung O.C. (2008). Prevalence and geographic distribution of childhood obesity in China in 2005. International Journal of Cardiology, 131(1), 1-8. Retrieved from http://dx.doi.org/10.1016/j.ijcard.2008.05.078.
10. Ma, R.C., Lin, X., & Jia, W. (2014). Causes of type 2 diabetes in China. Lancet Diabetes Endocrinology, 2(12), 980-991. Retrieved from http://dx.doi.org/10.1016/S2213-8587(14)70145-7.
11. Yang, G., Kong, L., Zhao, W., Wan, X., Zhai Y., Chen, L.C., & Koplan, J.P. (2008). Emergence of chronic non-communicable diseases in China. Lancet, 372(9650), 1697-705. Retrieved from http://dx.doi.org/10.1016/S0140-6736(08)61366-5.
12.  Asia Pacific Cohort Studies Collaboration. (2007). The burden of overweight and obesity in the Asia-Pacific region. Obesity Reviews, 8(3), 191–196.
13.  Gordon-Larsen, P., Wang, H., & Popkin, B.M. (2014). Overweight dynamics in Chinese children and adults. Obesity Reviews, 15(Suppl 1), 37–48. Retrieved from http://dx.doi.org/10.1111/obr.12121.
14.  Nettleton, J.A., Lutsey, P.L., Wang, Y., Lima, J.A., Michos, E.D., & Jacobs D.R. (2009). Diet soda intake and risk of incident metabolic syndrome and type 2 diabetes in the Multi-Ethnic Study of Atherosclerosis (MESA). Diabetes Care, 32(4), 688–694. Retrieved from http://dx.doi.org/10.2337/dc08-1799.
15.  Nazare, J.A., Smith, J.D., Borel, A.L., Haffner, S.M., Balkau, B., Ross, R., … & Despres, J.P. (2012). Ethnic influences on the relations between abdominal subcutaneous and visceral adiposity, liver fat, and cardiometabolic risk profile: the International Study of Prediction of Intra-Abdominal Adiposity and Its Relationship with Cardiometabolic Risk/Intra-Abdominal Adiposity. American Journal of Clinical Nutrition, 96(4), 714–726.
16. China national plan for NCD prevention treatment (2012-2015). (2012). Chinese Center for Disease Control and Prevention. Retrieved from http://www.chinacdc.cn/en/ne/201207/t20120725_64430.html.