• Research Review
• Journal Review

Authors: King H, Aubert RE, Herman WH

Reference: Diabetes Care 1998 (September); 21: 1414-1431

Reviewer: Elizabeth Lawler

Problem addressed: What is the global prevalence of diabetes, and how can it be expected to change until 2025?

Purpose of study: The purpose of this study was to provide numerical estimates and projections for the frequency of diabetes in all countries as a primary source of information and as a tool for health care planners.

Methods: Estimates of the number of people with diabetes in 35 countries at three points in time (1995, 2000, 2025) were drawn from an  earlier WHO study, and additional survey data was included from several other countries.

Separate urban and rural estimates were generated for developing nations based on previous observations of different risk factors for diabetes among urban vs rural populations in developed countries. Estimates of urbanization patterns were utilized to predict future population trends. When only urban or rural estimates of diabetes were available, the urban rate was assumed to be twice the rural rate. For countries without valid estimates of diabetes, extrapolation to the most similar country was used, based on ethnicity and socioeconomic status.

Results:

(Only global and regional results are reported in this article summary, with the exception of India and China which are considered regions according to the World Developing Report classification.)

Population Trends: Among developed countries, population size should remain relatively stable over the next 30 years. The estimated population in 1995 is approximately 857 million, 883 million in 2000, and 953 million in 2025.  Developing countries will have a much larger population increase of 80% from 2.5 billion in 1995, 2.8 billion in 2000, to more than 4 billion in 2025.  This increase would contribute to a global population increase of about 60% over 30 years from more than 3 billion to more than 5 billion.

Trends in Diabetes Prevalence: The prevalence of diabetes is higher among developed countries: 6% in 1995, 6.2% in 2000, and 7.6% in 2025. The developing world has a lower estimated prevalence: 3.3% in 1995, 3.5% in 2000, and 4.9% in 2025. This trend represents a 48% increase in prevalence.

Estimates of the diabetic population: The three countries with the greatest number of people with diabetes are, and will continue to be, India, China and the US. There will be a 42% increase in developed countries from 51 million to 72 million.  The increase in developing nations will be 170%, from 84 million to 228 million by the year 2025. By the year 2025 over 75% of all people with diabetes will be living in developing countries.

Age Specific Population Estimates:  Worldwide, the majority of diabetics are aged 45-64 (58.7 milllion) and this trend will continue, with an increasing majority of diabetics aged 45-64 in 2025 (141 million).  The majority of diabetics in developing countries is aged 45-64. This trend will continue in the year 2025. Regions which will follow a similar trend of an increasing majority of diabetics aged 45-64 are: Middle Eastern Crescent, Sub-Saharan Africa, India, China, Other Asian Countries and Islands, and Latin America and the Caribbean.  The most diabetics in developed nations are older >65 years, and this age-group will experience the greatest increase in numbers by the year 2025. The regions projected to follow this trend of an increasing majority of diabetics aged >65 are Established Market Economies and Former Socialist Europe.

Gender:  Worldwide there were more females than males with diabetes (73 vs 62 million) in 1995. This gap in the female vs male burden of disease is greater in developed countries (31 vs 21 million), with an equal burden of disease in developing nations 42 million for each). -The global trend is expected to reduce the female to male excess burden of disease by 2025 (159 vs 141 million).

Urban and Rural Trends:  For developing nations, with the exception of China and Sub-Saharan Africa, there were as many cases in urban as in rural regions in 1995. However, the trend is toward an excess of diabetes in urban areas. For developing countries the urban to rural excess is expected to rise from 1.6 in 1995 to 3.3 in 2025. Over the next 30 years, a 12-fold excess of diabetes is predicted for urban areas of Latin America and the Caribbean, a 4-fold excess in the Middle Eastern Crescent, and a 3-fold excess in India

Table 1: Estimated and projected prevalence (by percentage) of diabetes for 1995, 2000 and 2025

 

Table 2: Estimated and projected number of diabetics (in millions) for 1995, 2000 and 2025

Conclusions: The results suggest that for the world as a whole the prevalence of diabetes will increase between the years of 1995 to 2025, the adult population will increase by 64% and the prevalence of diabetes will increase by 35%, the number of people with diabetes by 122%.  Developing nations will have the greatest increases 82% population growth, 48% increase in the prevalence of diabetes and 170% increase in the number of diabetics.

The greater number of middle-aged diabetics, greater numbers of women than men with diabetes, and the increasing concentration of diabetes in urban areas are important findings and should be considered by public health officials when planning future health care systems and interventions.

Comments:  Because of lack of suitable data many extrapolations were necessary (all of the Sub-Saharan Africa estimates were based on data from Tanzania) and not all surveys were nationally representative or current. The emphasis should not be on estimates for individual countries, but trends in regions.

This study provides a startling picture of future trends in the prevalence and future global distribution of diabetes. It brings to the forefront the importance of diabetes as a health care issue, particularly for those regions where diabetes treatment and prevention has not been a public health priority.

Short of surveying the age-specific diabetes rates of every country, this study provides a reasonable recent approximation of the global trend in diabetes for the coming years. The epidemic trends presented are compelling and should receive careful attention, when there is still time to plan the allocation of scarce health care resources.