The global
burden
Diabetes and
impaired glucose
tolerance
Diabetes is one of the most common non-communicablediseases (NCDs). It is the fourth or fifth
leading cause of death in most high-income countriesand there is substantial evidence that it isepidemic in many economically developing andnewly industrialised countries.
Diabetes is undoubtedly one of the most challenginghealth problems of the 21st century.
The number of studies describing the possiblecauses and distribution of diabetes over the last
20 years has been extraordinary. These studiescontinue to confirm that it is the low- and middleincomecountries that face the greatest burdenof diabetes. However, many governments and
public health planners remain largely unaware ofthe current magnitude of and future potential forincreases in diabetes and its serious complications.Population-based diabetes studies consistentlyshow that a substantial proportion of those foundto have diabetes had not been previously diagnosed.Many people remain undiagnosed largelybecause there are few symptoms during the earlyyears of type 2 diabetes, or those symptoms maynot be recognised as being related to diabetes.
In addition to diabetes, impaired glucose tolerance(IGT), in which blood glucose levels are higher thannormal but not as high as in diabetes, is also amajor public health problem. People with IGT havea high risk of developing diabetes as well as anincreased risk of cardiovascular disease.
Prevalence and projections
In this edition of the IDF Diabetes Atlas, theprevalence of diabetes and IGT are estimated for
the years 2013 and 2035. Data are provided for219 countries and territories, grouped into the
seven IDF Regions: Africa (AFR), Europe (EUR),Middle East and North Africa (MENA), North
America and Caribbean (NAC), South and CentralAmerica (SACA), South-East Asia (SEA), and the
Western Pacific (WP).
Full details of the methods used to generate theprevalence estimates for diabetes in adults and theproportion undiagnosed, including how the datasources were evaluated and processed, can befound in the journal Diabetes Research and Clinical
Practice and on the IDF Diabetes Atlas website:
Complications
Complications due to diabetes (Chapter 1) are amajor cause of disability, reduced quality of life,and death. Diabetes complications can affectvarious parts of the body, manifesting in differentways in different people.There are no internationally agreed standards for
diagnosing and assessing diabetes complications.Due to the variety of methods of these studies, itis difficult to make comparisons between differentpopulations. However, it is clear that diabetescomplications are very common, with at leastone present in a large proportion of people withdiabetes (50% or more in some studies) at the time
of diagnosis.
In this edition of the IDF Diabetes Atlas, estimatesof complications were not included due to the lackof available comparable data. International standardsfor measuring complications are essentialto provide accurate estimates of this major causeof disability.
2.1 Diabetes
Diabetes can be found in every country. Withouteffective prevention and management programmes,
the burden will continue to increase worldwide.1Type 2 diabetes accounts for 85% to 95% of all
diabetes in high-income countries and may accountfor an even higher percentage in low- and middleincomecountries.1 Type 2 diabetes is a commoncondition and a serious global health problem.In most countries diabetes has increased alongsiderapid cultural and social changes: ageingpopulations, increasing urbanisation, dietarychanges, reduced physical activity and unhealthybehaviours.1Type 1 diabetes, although less common than type 2diabetes, is increasing each year in both rich andpoor countries. In most high-income countries, the
majority of diabetes in children and adolescentsis type 1 diabetes.
Gestational diabetes is common and, like obesityand type 2 diabetes, is increasing throughout theworld.2 The risk of developing type 2 diabetes ishigh in women who have had gestational diabetes.The reported prevalence of gestational diabetesvaries widely among different populations aroundthe world. Much of the variability is due to differencesin diagnostic criteria and study populations.
Prevalence
Some 382 million people worldwide, or 8.3% ofadults, are estimated to have diabetes. About
80% live in low- and middle-income countries. Ifthese trends continue, by 2035, some 592 millionpeople, or one adult in 10, will have diabetes. Thisequates to approximately three new cases every10 seconds, or almost 10 million per year. Thelargest increases will take place in the regionswhere developing economies are predominant.
Age distribution
Almost half of all adults with diabetes are betweenthe ages of 40 and 59 years. More than 80% of the184 million people with diabetes in this age grouplive in low- and middle-income countries.This age group will continue to comprise the greatestnumber of people with diabetes in the coming years.By 2035, it is expected that the number will increaseto 264 million. Again, more than 86% will be livingin low- and middle-income countries.
Gender distribution
There is little gender difference in the globalnumbers of people with diabetes for 2013 or
2035. There are about 14 million more menthan women with diabetes (198 million men vs
184 million women). However, this difference isexpected to increase to 15 million (303 million menvs 288 million women) by 2035.
Urban/rural distribution
There are more people with diabetes living inurban (246 million) than in rural (136 million)
areas although the numbers for rural areasare on the increase. In low- and middle-income countries, the number of people with diabetes inurban areas is 181 million, while 122 million livein rural areas. By 2035, the difference is expectedto widen, with 347 million people living in urbanareas and 145 million in rural areas.
2.2 Undiagnosed
diabetes
IDF estimates that as many as 175 million peopleworldwide, or close to half of all people with
diabetes, are unaware of their disease. Most ofthese cases are type 2 diabetes. The earlier a
person is diagnosed and management of diabetesbegins, the better the chances of preventing
harmful and costly complications. The need todiagnose and provide appropriate care to people
with diabetes is therefore urgent.
Disparities by region
No country has diagnosed every person that hasdiabetes. In sub-Saharan Africa, where resources
are often lacking and governments may notprioritise screening for diabetes, the proportion
of people with diabetes who are undiagnosed isas high as 90% in some countries.1 Even in highincomecountries, about one-third of people withdiabetes have not been diagnosed. The South-EastAsia Region (35.1 million) and the Western PacificRegion (74.7 million) together account for over 60%of all people with undiagnosed diabetes. Globally,84% of all people who are undiagnosed live in lowandmiddle-income countries.
Complications
A person with type 2 diabetes can live for severalyears without showing any symptoms. But duringthat time high blood glucose is silently damagingthe body and diabetes complications may bedeveloping. The complications associated withdiabetes are so varied that even when symptoms
do exist, diabetes may not be recognised as thecause unless accurate and appropriate testing is
carried out. Those who are undiagnosed will not betaking steps to manage their blood glucose levelsor lifestyle. Studies have found that many peoplewith undiagnosed diabetes already have complications,such as chronic kidney disease and heartfailure, retinopathy
and neuropathy.have long-standing undiagnosed diabetes,the potential benefits of early diagnosis and treatmentare lost. Furthermore, the costs related toundiagnosed diabetes are considerable. One studyfrom the USA found that undiagnosed diabeteswas responsible for an additional USD 18 billionin healthcare costs in one year.5
Identifying people
with diabetes
Opportunistic identification of people with riskfactors for undiagnosed type 2 diabetes is feasibleand cost-effective.6 Risk scores and ‘tick tests’listing risk factors have been developed in manycountries based on epidemiological surveys ofthe local populations, and are widely available.While undiagnosed diabetes is a substantialproblem, population-wide screening for diabetesis not appropriate. Countries must first develophealth systems that can meet the needs ofpeople living with the disease. Priority shouldbe given to providing good care and treatment topeople already identified with diabetes. Targetedscreening for those at high risk of undiagnoseddiabetes may be considered once a working systemfor care is in place.
Estimating undiagnosed
diabetes
Population-based studies provide the basis for estimatingundiagnosed diabetes. A sample of peopleliving in a particular area is tested for diabetes,which identifies both known and previously undiagnosedcases. The IDF Diabetes Atlas estimatesundiagnosed diabetes using representative population-based studies reporting the proportion ofpreviously undiagnosed cases. The findings fromthese studies are then combined by Region andincome group to generate an estimate that is laterapplied to the prevalence estimates. Full detailsof the methods and results are available in thepublished paper at
2.3 Impaired glucose
tolerance
Impaired glucose tolerance (IGT), along withimpaired fasting glucose (IFG), is recognised as
being a stage preceding diabetes when bloodglucose levels are higher than normal. Thus,
people with IGT are at high risk of developingtype 2 diabetes, although all people with IGT do
not always go on to develop the disease. In morethan one-third of people with IGT, blood glucoselevels will return to normal over a period of severalyears.1
Data on IGT are included in this report becauseIGT greatly increases the risk of developing type 2diabetes1 and it is linked with the development ofcardiovascular disease.2,3 In addition, some of thebest evidence on the prevention of type 2 diabetescomes from studies involving people with IGT.
Prevalence
Some 316 million people worldwide, or 6.9% ofadults, are estimated to have IGT. The vast majority(70%) of these people live in low- and middleincomecountries. By 2035, the number of peoplewith IGT is projected to increase to 471 million, or8.0% of the adult population.
Age distribution
The majority of adults with IGT are under the ageof 50 (153 million) and, if left untreated, are athigh risk of progressing to type 2 diabetes laterin life. This age group will continue to have thehighest number of people with IGT in 2035, risingto 198 million, as shown in Figure 2.3. It is importantto note that nearly one-third of all those whocurrently have IGT are in the 20 to 39 year agegroup, and are therefore likely to spend many years
at high risk – if indeed they do not go on to developdiabetes.
The prevalence of IGT is generally similar to thatof diabetes, but somewhat higher in the Africa andEurope Regions and lower in the South-East AsiaRegion.
2.4 Diabetes
in young people
Type 1 diabetes is one of the most common endocrineand metabolic conditions in childhood.
The number of children developing this form ofdiabetes every year is increasing rapidly, especiallyamong the youngest children. In a growingnumber of countries, type 2 diabetes is also beingdiagnosed in children.
The challenges
In type 1 diabetes, insulin therapy is life-savingand lifelong. A person with type 1 diabetes needsto follow a structured self-management plan,including insulin use and blood glucose monitoring,physical activity, and a healthy diet. Inmany countries, especially in low-income families,access to self-care tools, including self-managementeducation, as well as to insulin, is limited.This leads to severe disability and early death inchildren with diabetes.
Many children and adolescents may find it difficultto cope emotionally with their disease. Diabetescan result in discrimination and may limit socialrelationships. It may also have an impact on achild’s academic performance. The costs of treatmentand monitoring equipment, combined withthe daily needs of a child with diabetes, may place a serious financial and emotional burden on thewhole family.
Incidence and prevalence
Three major collaborative projects, the DiabetesMondiale study (DIAMOND),1 the Europe and
Diabetes study (EURODIAB),2 and the SEARCH forDiabetes in Youth study3 have been instrumental
in monitoring trends in incidence (the number ofpeople developing a disease in a year). This hasbeen done by setting up population-based regionalor national registries using standardised definitions,data collection forms, and methods forvalidation.
The incidence of type 1 diabetes among children isincreasing in many countries, particularly in childrenunder the age of 15 years. There are strongindications of geographic differences in trendsbut the overall annual increase is estimated tobe around 3%.1,2 Evidence shows that incidenceis increasing more steeply in some Central andEastern European countries, where the diseaseis less common. Also, several European studieshave suggested that, in relative terms, increasesare greatest among younger children.There is also evidence that similar trends exist inmany other parts of the world, but in sub-SaharanAfrica incidence data are limited or non-existent.Special efforts must be made to collect more data,especially in those countries where diagnoses maybe missed.
Some 79,100 children under 15 years are estimated to develop type 1 diabetes annually worldwide. Of the estimated 497,100 children living with type 1 diabetes, 26% live in the Europe Region, where the most reliable and up-to-date estimates of incidence are available, and 22% in the North America and Caribbean Region.
Type 2 diabetes inyoung people
There is evidence that type 2 diabetes in children and adolescents is increasing in some countries.However, reliable data are sparse.4 As with type 1diabetes, many children with type 2 diabetes riskdeveloping complications in early adulthood, which would place a significant burden on the familyand society. With increasing levels of obesity and
physical inactivity among young people in many countries, type 2 diabetes in childhood has the
potential to become a global public health issue leading to serious health outcomes. More informationabout this aspect of the diabetes epidemic isurgently needed.
2.5 Hyperglycaemiain pregnancy
High blood glucose, or hyperglycaemia, is one ofthe most common health problems of pregnancy.1
Hyperglycaemia in pregnancy can be a result ofeither previously existing diabetes in a pregnant
woman, or the development of insulin resistancelater in the pregnancy in a condition known as
gestational diabetes. Unlike diabetes in pregnancy,gestational diabetes resolves once the pregnancyends. Hyperglycaemia in pregnancy is categorized as either diabetes in pregnancy or
gestational diabetes, depending on blood glucosevalues obtained during screening.
Risks and complications
Any unmanaged hyperglycaemia in pregnancycan result in birth complications that can affect
both mother and child including: increased riskof preeclampsia, obstructed labour due to fetalmacrosomia and hypoglycaemia at birth forthe infant.
As the prevalence of both obesity and diabetes inwomen of childbearing age continue to rise in allregions, so will the prevalence of hyperglycaemiain pregnancy. In addition, women who developgestational diabetes have an increased lifetimerisk of developing type 2 diabetes.2 Babies born tomothers who have hyperglycaemia in pregnancyare also at an increased risk of developing type 2diabetes later in life.
Prevalence
IDF estimates that 21.4 million or 16.8% of livebirths to women in 2013 had some form of hyperglycaemiain pregnancy. An estimated 16% of thosecases were due to diabetes in pregnancy and wouldrequire careful monitoring during the pregnancy
and follow-up post-partum.There are some regional differences in the prevalence
(%) of hyperglycaemia in pregnancy, with theSouth-East Asia Region having the highest prevalenceat 25.0% compared to 10.4% in the NorthAmerica and Caribbean Region. A staggering91.6% of cases of hyperglycaemia in pregnancywere in low- and middle-income countries, where
access to maternal care is often limited.The prevalence of hyperglycaemia in pregnancyincreases rapidly with age and is highest in womenover the age of 45 (47.7%), although there arefewer pregnancies in that age group. This explainswhy just 23% of global cases of hyperglycaemia inpregnancy occurred in women over the age of 35,
even though the risk of developing the conditionis higher in these women.
Estimating prevalence
There is great diversity in the methods and criteriaused for identifying women with hyperglycaemia inpregnancy, which increases the difficulty of makingcomparisons between studies and generatingestimates on prevalence.2 However, the recentpublication of a guideline from the World HealthOrganization on diagnosing hyperglycaemia inpregnancy will contribute to a standard approachto estimating prevalence.3Data on hyperglycaemia in pregnancy from studies
were available for 34 countries across all IDFRegions. Although each of the Regions was represented,the majority of the studies were carriedout in high-income countries. More informationis available on the methods used to generateused to generate theestimates at
2.6 Mortality
Diabetes and its complications are major causesof early death in most countries. Cardiovascular
disease (see Chapter 1) is one of the leadingcauses of death among people with diabetes. It can
account for 50% or more of deaths due to diabetesin some populations. Estimating the number ofdeaths due to diabetes is challenging because onthe one hand, more than a third of countries donot have any data on diabetes-related mortality;and on the other, because existing routine healthstatistics underestimate the number of deaths dueto diabetes. To provide a more realistic estimate ofmortality, the IDF Diabetes Atlas uses a modeling approach to estimate the number of deaths thatcan be attributed to diabetes.1
Burden of mortality
Approximately 5.1 million people aged between 20and 79 years died from diabetes in 2013, accountingfor 8.4% of global all-cause mortality amongpeople in this age group. This estimated numberof deaths is similar in magnitude to the combineddeaths from several infectious diseases that aremajor public health priorities,* and is equivalentto one death every six seconds. Close to half (48%)of deaths due to diabetes are in people under theage of 60. The highest number of deaths due todiabetes occurred in countries with the largestnumbers of people with the disease: China, India,USA, and the Russian Federation.
Gender distribution
There is very little difference between men andwomen in the total number of deaths due to
diabetes. However, there are important differencesin the distribution of these deaths.
In all but the Middle East and North Africa, andWestern Pacific Regions, diabetes accounts for
a higher proportion of deaths in women than inmen, representing up to a quarter of all deaths
in middle-aged women. This disparity is likely tobe due to higher rates of mortality in men fromother causes.
Trends
The number of deaths attributable to diabetes in2013 showed an 11% increase over estimates for
2011.1,2 This increase was largely due to rises inthe number of deaths due to the disease in theAfrica, Western Pacific, and Middle East and NorthAfrica Regions. This can be explained in part by arise in diabetes prevalence in some highly populatedcountries in each Region. While there hasbeen a documented decline in mortality from someNCDs in some countries,3 no such decline has beenreported for diabetes.