Epidemiology and Morbidity

Diabetes and Impaired Glucose Tolerance

Global Burden: Prevalence and Projections, 2010 and 2030

At a glance

	2010	2030
Total world population (billions)	7.0	8.4
Adult population (20-79 years, billions)	4.3	5.6

Diabetes and IGT (20-79 years)
Diabetes
Global prevalence (%)	6.6	7.8
Comparative prevalence (%)	6.4	7.7
Number of people with diabetes (millions)	285	438

IGT
Global prevalence (%)	7.9	8.4
Comparative prevalence (%)	7.8	8.4
Number of people with IGT (millions)	344	472

Diabetes mellitus (DM) is now one of the most common non-communicable diseases globally. It is the fourth or fifth leading cause of death in most high-income countries and there is substantial evidence that it is epidemic in many economically developing and newly industrialized nations. Complications from diabetes, such as coronary artery and peripheral vascular disease, stroke, diabetic neuropathy, amputations, renal failure and blindness are resulting in increasing disability, reduced life expectancy and enormous health costs for virtually every society. Diabetes is undoubtedly one of the most challenging health problems in the 21st century.

The number of studies describing the epidemiology of diabetes over the last 20 years has been extraordinary. It is now recognized that it is the low- and middle income countries (LMCs) that face the greatest burden of diabetes. However, many governments and public health planners still remain largely unaware of the current magnitude, or, more importantly, the future potential for increases in diabetes and its serious complications in their own countries.

It has been a consistent finding of population-based diabetes studies that a substantial proportion of all people found to have diabetes had not been previously diagnosed. The uncovering of new cases when mass blood testing is undertaken is primarily because of the lack of symptoms associated with the early years of type 2 diabetes, meaning that those with diabetes may be unaware of their condition and therefore not seek medical attention for it.

In addition to diabetes, the condition of impaired glucose tolerance also constitutes a major public health problem, both because of its association with diabetes incidence and its own association with an increased risk of cardiovascular disease.

In this edition of the IDF Diabetes Atlas, the prevalence of diabetes mellitus and IGT has been estimated for each country for the years 2010 and 2030. Data are provided for 216 countries and territories, which have been allocated into one of the seven IDF regions: Africa (AFR), Europe (EUR), Middle East and North Africa (MENA), North America and Caribbean (NAC), South and Central America (SACA), South-East Asia (SEA), and the Western Pacific (WP).

The data presented for adults are for types 1 and 2 diabetes combined, and IGT. Only adults aged from 20 to 79 years are considered because the majority of all people who have diabetes and IGT are adults. Estimates for type 1 diabetes in children and adolescents are presented in the section on Diabetes in the Young [10].

Two sets of prevalence estimates have been provided in this report: the national, regional or global prevalence (the crude prevalence) and the comparative prevalence. The national, regional or global prevalence indicates the percentage of a particular population that has diabetes. It is appropriate for assessing the burden of diabetes for each country or region. The comparative prevalence is used for making comparisons between countries or regions. It has been calculated by assuming that every country or region has the same age profile (the age profile of the world population has been used). This reduces the effect of the differences of age between countries or regions, and makes this figure approriate for making comparisons.

The data presented here should be interpreted cautiously as general indicators of diabetes frequency, and the estimates will need to be revised as new and better epidemiological information becomes available. Comparison of country, regional, and even global prevalence from one report to the next should be performed with extreme caution. Large changes in the prevalence or numbers of people with diabetes from one edition of the IDF Diabetes Atlas to another are usually due to the use of a more recent study rather than a change in the profile of diabetes within that country. Data sources for this edition include 34 new studies. Thus, the inclusion of recent, and more reliable research brings us closer to the actual rates of diabetes, but these limitations need to be always considered. The key purpose of reports such as these is to stimulate action in the form of preventive and management programmes, as well as further research.

The background paper, Diabetes and Impaired Glucose Tolerance, and country by country estimates on which this summary is based are available in the Downloads [11] section.

Diabetes

Diabetes mellitus can be found in almost every population in the world and epidemiological evidence suggests that, without effective prevention and control programmes, diabetes will likely continue to increase globally 1 .

Type 1 diabetes usually accounts for only a minority of the total burden of diabetes in a population but is increasing in incidence in both poor and rich countries. It is the predominant form of the disease in younger age groups in most high-income countries (see Diabetes in the Young [10]).

Type 2 diabetes constitutes about 85 to 95% of all diabetes in high-income countries 1 and may account for an even higher percentage in low- and middle-income countries. Type 2 diabetes is now a common and serious global health problem, which, for most countries, has evolved in association with rapid cultural and social changes, ageing populations, increasing urbanization, dietary changes, reduced physical activity and other unhealthy lifestyle and behavioural patterns 1 .

Gestational diabetes mellitus is common and, like obesity and type 2 diabetes that are related conditions, is increasing in frequency throughout the world. The risk of developing diabetes after GDM is very high. As the prevalence of type 2 diabetes increases within a population so will the prevalence of GDM 2 . The reported prevalence of GDM has varied widely among different populations around the world. Much of the variability is due to differences in diagnostic criteria and detection methods used in different centres. However, it has not been possible to estimate the prevalence of GDM separately as there are very limited population-based studies on GDM. It is recognized that the challenges of GDM have to be addressed and further research is required in this area.

The methods used here to estimate the prevalence of diabetes are conservative and are mostly based on changes in population size and age sturcture. It has not been possible in these projections to take any account of trends in obesity although the projections for LMCs do take into account trends in urbanization. If levels of obesity continue to increase it is possible that the prevalence of diabetes will be even greater than reported here.

Prevalence

It is estimated that approximately 285 million people worldwide, or 6.6%, in the age group 20-79, will have diabetes in 2010, some 70% of whom live in low- and middle-income countries. This number is expected to increase by more than 50% in the next 20 years if preventive programmes are not put in place. By 2030, some 438 million people, or 7.8% of the adult population, are projected to have diabetes. The largest increases will take place in the regions dominated by developing economies (see Figure 2.1)

Age distribution

The 40-59 age group currently has the greatest number of people with diabetes with some 132 million in 2010, more than 75% of whom live in low- and middle-income countries.

By 2030, it is projected that there will be 188 million people with diabetes aged 40-59 years. More than 80% will be found in newly developed or developing countries. There will be even more people in the 60-79 age group, at some 196 million (see Figure 2.2).

Gender distribution

The estimates for both 2010 and 2030 showed little gender difference in the number of people with diabetes. For 2010 there are expected to be about one million more women than men with diabetes (143 million women vs 142 million men). However, this difference is expected to increase to six million by 2030 (222 million women vs 216 million men).

Urban/rural distribution

There are more people with diabetes living in urban than in rural areas. In the LMCs, estimates put the number of people with diabetes in urban areas to be 113 million in 2010, compared to 78 million in rural areas. By 2030 it is expected that this discrepancy will increase to 228 million people with diabetes in urban areas and 99 million in rural communities.

Map 2.1 Prevalence (%) estimates of diabetes (20-79 years), 2010

[17]

Map 2.2 Prevalence (%) estimates of diabetes (20-79 years), 2030

[18]

1: World Health Organization. Prevention of diabetes mellitus. Report of a WHO Study Group. Geneva: World Health Organization; 1994. No. 844. [19]

2: Hunt KJ, Schuller KL. The increasing prevalence of diabetes in pregnancy. Obstet Gynecol Clin North Am 2007; 34 (2): 173-99, vii.

Impaired Glucose Tolerance

Impaired glucose tolerance, along with impaired fasting glucose (IFG), is recognized as being a stage in the transition from normality to diabetes. Thus, individuals with IGT are at high risk of progressing to type 2 diabetes, although such progression is not inevitable, and probably over 30% of individuals with IGT will return to normal glucose tolerance over a period of several years.

The decision to include data on IGT was based on two major factors associated with its presence: it greatly increases the risk of developing diabetes 1 , and it is associated with the development of cardiovascular disease 2 3 . In addition, some of the best evidence we have on the prevention of type 2 diabetes comes from studies in people with IGT.

Prevalence

It is estimated that some 344 million people worldwide, or 7.9% in the age group 20-79, will have IGT in 2010, the vast majority of whom live in low- and middle-income countries. By 2030 the number of people with IGT is projected to increase to 472 million, or 8.4% of the adult population.

Age distribution

As with diabetes, the 40-59 age group is expected to have the greatest number of people with IGT with 138 million for 2010, and this will remain true in 2030 with 186 million as shown in Figure 2.3. It is also of note that nearly one-third of all those who will have IGT for 2010 are in the 20-39 age group (see Figure 2.3).

The prevalence of IGT is generally similar to that of diabetes, but somewhat higher for the African and Western Pacific Regions, and slightly lower in the North America and Caribbean Region.

Map 2.3 Prevalence* (%) estimates of impaired glucose tolerance (20-79 years), 2010

[25]

1: Shaw JE, Zimmet PZ, de Courten M, et al. Impaired fasting glucose or impaired glucose tolerance. What best predicts future diabetes in Mauritius? Diabetes Care 1999; 22 (3): 399-402.

2: Perry RC, Baron AD. Impaired glucose tolerance. Why is it not a disease? Diabetes Care 1999; 22 (6): 883-885.

3: Tominaga M, Eguchi H, Manaka H, et al. Impaired glucose tolerance is a risk factor for cardiovascular disease, but not impaired fasting glucose. The Funagata Diabetes Study. Diabetes Care 1999; 22 (6): 920-924.

Diabetes in the Young: a Global Perspective

At a Glance

	2010
Total child population (0-14 years, billions)	1.9

Type 1 diabetes in children (0-14 years)
Number of children with type 1 diabetes (thousands)	479.6
Number of newly-diagnosed cases per year (thousands)	75.8
Annual increase incidence (%)	3.0

Type 1 diabetes is rapidly increasing in children and adolescents in many countries, and evidence suggests that in a growing number of countries type 2 diabetes is now also being diagnosed in childhood.

Challenges of type 1 diabetes in children

Type 1 diabetes is one of the most common endocrine and metabolic conditions in childhood, and incidence is rapidly increasing especially among the youngest children. Insulin treatment is life-saving and lifelong. Self-discipline and adherence to a balanced diet are necessary if the disease is to be well managed. In many countries, especially in less privileged families, access to self-care tools and also to insulin is limited and this may lead to severe handicap and early death in children with diabetes.

Many children and adolescents find it difficult to cope emotionally with their condition. Diabetes causes them embarrassment, results in discrimination and limits social relationships. It may impact on school performance and family functioning. The financial burden may be aggravated by the costs of treatment and monitoring equipment.

Trends in incidence

Two international collaborative projects, the Diabetes Mondiale study (DiaMond) 1 and the Europe and Diabetes study (EURODIAB) 2 have been instrumental in monitoring trends in incidence through the establishment of population-based regional or national registries using standardized definitions, data collection forms and methods for validation.

The incidence of childhood onset type 1 diabetes is increasing in many countries in the world, at least in the under 15-year age group. There are strong indications of geographic differences in trends but the overall annual increase is estimated to be around 3%. There is evidence that incidence is increasing more steeply in some of the low prevalence countries such as those in central and eastern Europe. Moreover, several European studies have suggested that, in relative terms, increases are greatest in young children. There are clear indications that similar trends exist in many other parts of the world, but in sub-Saharan Africa incidence data are sparse or non–existent. Special efforts must be made to collect data, especially in those countries where diagnosis may be missed or neglected and, as a result, children die because they do not receive insulin.

Prevalence of type 1 diabetes in children

It is estimated that annually some 76,000 children aged under 15 years develop type 1 diabetes worldwide. Of the estimated 480,000 children with type 1 diabetes, 24% come from the South-East Asian Region, but the European Region, where the most reliable and up-to-date estimates of incidence are available, comes a close second (23%) (see Figure 2.4).

The continued mapping of global trends in incidence and prevalence of type 1 diabetes in all age groups, through use of data from existing and new registries, is thus important, and in conjunction with other scientific research may provide a logical basis for intervention studies and future primary prevention strategies which must be the ultimate goal.

The background paper, Diabetes in the Young, and country by country estimates on which the summary on type 1 diabetes in the young is based are available in the Downloads [11] section.

Type 2 diabetes in the young

Type 2 diabetes in children and adolescents is on the increase in all countries, whether poor or rich. As with type 1 diabetes, many children with type 2 diabetes risk developing complications at an early age, which would place a significant burden on the family and society. There is growing recognition that type 2 diabetes in the young is becoming a global public health issue with a potentially serious health outcome 3 , in spite of the paucity of information in this area. A review of studies on type 2 diabetes in the young is available in the Diabetes Atlas, third edition 4 .

Map 2.4 New cases of type 1 diabetes in children, 0-14 years (cases per 100,000 aged 0-14 years per year), 2010

[31]

1: D.I.A.M.O.N.D. Project Group. Incidence and trends of childhood Type 1 diabetes worldwide 1990-1999. Diabet Med 2006; 23 (8): 857-866.

2: Patterson CC, Dahlquist GG, Gyürüs E, et al. Incidence trends for childhood type 1 diabetes in Europe during 1989-2003 and predicted new cases 2005-20: a multicentre prospective registration study. Lancet 2009; 373 (9680): 2027-2033.

3: Fagot-Campagna A, Narayan KM, Imperatore G. Type 2 diabetes in children. BMJ 2001; 322 (7283): 377-378.

4: International Diabetes Federation. The Diabetes Atlas. Third Edition. Brussels: International Diabetes Federation; 2006.