Diabetes has traditionally been viewed as a disease of rich countries. However, estimates of diabetes prevalence presented in this edition of the IDF Diabetes Atlas show that four out of five people with diabetes live in countries classified by the World Bank as low- and middle-income countries. Of the 3.6 billion adults living in low- and middle-income countries in 2011, 291 million have diabetes. 1 This is compared to 75 million adults with diabetes living in high-income countries.
Drivers of the epidemic
The greatest increases in numbers of people with diabetes over the next 20 years will occur in low- and middle-income countries. This is driven by an increase in the adult population, people living longer, and through changes in behaviours associated with rapidly increasing urbanization and development. Key changes in behaviour include reduced physical activity, a shift to higher calorie diets, and the associated increases in obesity. This transition becomes clearer when breaking down middle-income countries further into upper-middle-income and lower-middle-income. The prevalence of diabetes is higher in upper middle-income countries (10.1%) than in lower middle-income countries (8.6%).
The majority of people with diabetes in low- and middle-income countries are under 60 years of age and in the peak of their productive years. This is different from the age distribution found in high-income countries which has many more people with diabetes in older age groups. People with poorly managed diabetes or people who do not have access to proper care and treatment are more likely to miss work due to the consequences of the disease, which can lead to lost productivity. This in turn has a negative effect on the economy in those countries.
Changes as economies develop
Figure 4.2 suggests an alarming scenario for lower middle-income countries in particular. With ageing the prevalence in lower middle-income countries is likely to increase and so be higher across all ages than in high-income countries. Currently, in ages 60 and above, the prevalence of diabetes is lower than it is in high-income countries. However, under the age of 60, the prevalence is currently higher than in high-income countries. As these people in lower middle-income countries age, there is likely to be a rapid increase in the prevalence of diabetes in those over the age of 60, shifting the curve towards a distribution more similar to upper middle-income countries.
Furthermore, as upper middle-income country economies develop into high-income economies, it is unlikely that the prevalence of diabetes in those countries will decrease.
There are nearly as many deaths due to diabetes in low-income countries (492,000) as in high-income countries (544,000), even though low-income countries have the lowest diabetes prevalence (5.6%) and a smaller adult population (509 million) than high-income countries (789 million). This reflects greater mortality due to diabetes in low-income countries compared to high-income. Middle-income countries have by far the largest number of total deaths attributable to diabetes at over 3.5 million deaths.
The comparative mortality rate (20-79 years) due to diabetes in high-income countries (0.51 per 1,000) is less than half of that of low- and middle-income countries (1.22 per 1,000).
Eighty-two percent of all healthcare expenditures due to diabetes are in high-income countries at USD 383.8 billion in 2011. In contrast, just USD 1.1 billion was spent in low-income countries. A lack of investment in the care and treatment of people with diabetes in low-income countries may explain the difference in expenditures as well as the high relative mortality rate.
Differences within countries
It is essential to the understanding of these differences to look at the drivers of disparities between and within countries. A country-level analysis only gives a snapshot of what is driving new cases of diabetes. Different levels of socio-economic status can mean a very different picture for individuals with diabetes living in a particular environment and the next chapter on the Social Determinants of Diabetes explores these relationships in more depth.
1: The World Bank. Country and Lending Groups 2011. http://data.worldbank.org/about/country-classifications/countr-and-lending-groups [Accessed 2011-08-23]