Paul Z Zimmet, Dianna J Magliano, William H Herman, Jonathan E Shaw
The number of people with diabetes worldwide has more than doubled during the past 20 years. One of the most worrying features of this rapid increase is the emergence of type 2 diabetes in children, adolescents, and young adults.
Lifestyle changes and globalisation have, during the past five decades, resulted in remarkable changes in societies, political systems, the environment, and human behaviour. The number of people with diabetes and obesity has increased substantially in both developed and developing countries, with the greatest burden tending to fall on socially disadvantaged groups and Indigenous peoples.
Paradoxically, the burden of this so-called western disease, caused by western lifestyles, has the greatest effect on developing countries; more than 80% of the global total of people with diabetes live in these countries.
cInternational health agencies and national governments ignored the rise and rise of diabetes and other noncommunicable diseases until quite recently. Funding for the prevention and control of such diseases (including diabetes) was of low priority compared with funding for the control of communicable diseases.
In 2011, the UN General Assembly made a political declaration on the prevention and control of non-communicable diseases, which was followed by a call by the World Health Assembly to reduce avoidable mortality from non-communicable diseases by 25% by 2025. However, it remains true that, despite global rhetoric and resolutions, noncommunicable diseases are still the least recognised group of conditions that threaten the future of human health and wellbeing.
In 1994, 110 million people worldwide were estimated to have diabetes, and by 2010 the number was predicted to increase to 239 million. In 1998, King and colleagues reported that 135 million people had diabetes in 1995, and predicted that 300 million would have the disease by 2025. A later report suggested that 171 million people had diabetes in 2000, which would increase to 366 million by 2030. However, recent findings suggest that the burden was consistently underestimated.
The latest prediction from the International Diabetes Federation is that 382 million people are lisving with diabetes in 2013 (a number previously forecast for 2030), and that by 2035 the number will be almost 600 million.
“The latest prediction from the International Diabetes Federation is that 382 million people are living with diabetes in 2013 (a number previously forecast for 2030)…”
The global increase in urbanisation and technology has been associated with decreasing physical activity, which might exacerbate the epidemic of type 2 diabetes. Ng and Popkin reported substantial reductions in physical activity and increased sedentary behaviour in a study that used cross-sectional and longitudinal datasets from five countries (Brazil, China, India, the UK, and the USA). The authors noted that reduced activity and increased sedentary behaviour worldwide will represent a major threat to health, as a result of the potential effect on weight gain and other cardiometabolic health risks.
The global epidemiology of diabetes is changing. Type 2 diabetes was traditionally thought of as a disorder of middle-aged and elderly people, and almost exclusively as an adult disorder. However, diabetes has become more common, not only in young adults, but also in adolescents and children. This change has occurred predominantly in Indigenous populations and other high-prevalence groups.
Diabetes in children and adolescents
The highest prevalence of type 2 diabetes in children and adolescents occurs in high-risk ethnic groups, which include Indigenous populations (particularly in North America and Australia), Pacific Islanders, African Americans, Hispanics, and some Asian populations. The incidence of type 2 diabetes is six times higher in Australian Indigenous youth than in Australian young people generally. Australia’s Indigenous people experience a disproportionately high rate of type 2 diabetes, and the most striking feature of the diabetes epidemic in Australia is the premature age of onset.
The incidence of type 2 diabetes is six times higher in Australian Indigenous youth than in Australian young people generally.”
In New Zealand, the incidence of type 2 diabetes in childhood or adolescence increased five-fold between 1995 and 2007. Most patients were of Pacific island or Maori ethnicity. In the SEARCH for Diabetes in Youth Study in the USA, young people aged 15-19 years from ethnic-minority populations had a higher incidence of diabetes than did non-Hispanic whites. Between 1995 and 2007, the annual incidence of type 2 diabetes in children younger than 15 years increased five-fold. As obesity in young people increases in Asian countries such as China and India, without effective intervention strategies to reduce obesity, more people will develop type 2 diabetes at younger ages. Yan and colleagues noted, with concern, that the prevalence of diabetes is already higher in Chinese children than in US children.
Treating young people with diabetes
Management of type 2 diabetes in a child or adolescent is entirely different from that of diabetes in adults. Lifestyle change and adherence to medication are difficult to achieve, and diabetes onset so early in life usually means many years of disease and treatment. In addition to the effect of long duration of diabetes, other factors (such as poor metabolic control) seem to put adolescents with type 2 diabetes at a particularly high risk of development of both microvascular and macrovascular complications. Indeed, investigators of a recent modelling study estimated that type 2 diabetes that develops between the ages of 15 and 24 years will result in a lifetime risk of microalbuminuria of close to 100%, a lifetime risk of blindness of 20%, and 15 years of life lost. Furthermore, therapeutic options during childhood are limited by the lack of safety and efficacy data for treatments other than insulin in this age group.
The costs of care in young adults and the lifetime economic effects on productivity associated with diabetes are future challenges, particularly in developing countries. The magnitude of the probable effect of younger onset of disease is obvious in comparisons of age profiles between high-income and low-income countries. In low-income and middle-income countries, the largest groups of people with diabetes are of working age (40-59 years). This finding differs from the classic age distribution of diabetes in high-income countries, in which most people with diabetes are aged 60-79 years.
“The costs of care in young adults and the lifetime economic effects on productivity associated with diabetes are future challenges…”
The cost of diabetes
The economic effect of diabetes is enormous. In 2010, global health expenditure attributable to diabetes was estimated to be US$376 billion-that is, 12% of all global health expenditure. In the USA in 2012, the direct medical cost of diabetes was $176 billion.
Prevention of diabetes, its complications, and associated disorders, such as cardiovascular disease, should be an essential component of future public health strategies for all countries.