The number of people in a given group or population who is reported to have a disease at any point in time.
Diabetes mellitus
Impaired glucose tolerance
Estimates of the prevalence of diabetes and impaired glucose tolerance (IGT) for the years 2003 and 2025 are available for 212 countries and territories, which have been allocated into one of the seven IDF regions: Africa (AFR), Eastern Mediterranean and Middle East (EMME), Europe (EUR), North America (NA), South and Central America (SACA), South-East Asia (SEA) and Western Pacific (WP).
Rates for each country have not been age-standardized, but are presented as the crude rates for the specific country and region according to the number of persons aged 20-79 years for that national or geographical entity. Furthermore as the emphasis is on numbers of persons with diabetes and IGT for each country, prevalence rates are markedly affected by the population age distribution so that those countries with older age distributions will inevitably have higher crude prevalences for the 20-79 year age group.
The consequence of applying current age and gender specific prevalence rates to estimate 2025 prevalences and number of cases is that only changes in the age and urban/rural distribution of the population will affect the estimates. Since it is likely that the age specific prevalence rates (the prevalence at any given age) will rise due to increasing obesity, the figures are probably underestimates.
Type 2 diabetes in children and adolescents is acknowledged as a very important and growing problem, and a review of studies in this area is available on the e-Atlas.
The principal aspects of the determination of prevalence were:
Although the tables on prevalence estimates contain data listed to one decimal point, it should not be inferred that this indicates the degree of precision, but rather to facilitate calculations and the appearance of the tables. In general, no predictions of diabetes or IGT numbers should be taken as having reliability of more than one significant figure.
Further details of methodology and discussion of results are available in the Diabetes Atlas, second edition.
The global burden of diabetes has been estimated several times. In 1994, the International Diabetes Federation Directory5International Diabetes Federation. Triennial Report (1991-1994) and Directory. International Diabetes Federation, Brussels, 1994. contained type 1 and type 2 diabetes estimates supplied by member nations. Using these data IDF estimated that over 100 million people worldwide had diabetes. Also in 1994, McCarty et al6McCarty D, Zimmet P. Diabetes 1994 to 2010: Global Estimates and Projections. International Diabetes Institute, Melbourne, 1994. used data from population-based epidemiological studies and estimated that the global burden of diabetes was 110 million in 1994 and that it would likely more than double to 239 million by 2010.
WHO1King H, Aubert R, Herman W. Global burden of diabetes, 1995-2025. Prevalence, numerical estimates and projections. Diabetes Care 1998; 21:1414-1431. also produced a report using epidemiological information and estimated the global burden at 135 million in 1995, with the number reaching 299 million by the year 2025. In 1997, Amos et al7Amos A, McCarty D, Zimmet P. The rising global burden of diabetes and its complications: Estimates and projections to the year 2010. Diabet Med 1997; 14:S1-S85. estimated the global burden of diabetes to be 124 million people, and projected that this would increase to 221 million people by the year 2010. Despite using different methodologies, and at times showing large differences in country-specific estimates, these reports have arrived at remarkably similar global figures of diabetes.