IDF estimates that globally as many as 183 million people, or half of those who have diabetes, are unaware of their condition. Most of these have type 2 diabetes. The earlier a person is diagnosed and management of diabetes begins, the better the chances of preventing harmful and costly complications. The urgent need for diagnosing and providing appropriate care to people with diabetes is therefore very high.
Disparities by region
No country has diagnosed every person that has diabetes. In sub-Saharan Africa, where resources are often lacking and governments may not prioritize screening for diabetes, the proportion of people with diabetes who are undiagnosed can reach up to 90% in some countries. 1 Even in high-income countries, about one-third of people with diabetes have not been diagnosed. The South-East Asia Region (36.2 million) and the Western Pacific Region (73.5 million) together account for over 60% of all people with undiagnosed diabetes. Globally, 85% of all people who remain undiagnosed with diabetes are in low- and middle-income countries.
A person with diabetes can live for several years without showing any symptoms, during which time high blood glucose is silently damaging the body and diabetes complications may be developing. The complications associated with diabetes are so varied that even when symptoms do exist, diabetes may not be thought to be the cause unless accurate and appropriate testing is carried out. Those who are undiagnosed will not be taking steps to manage their blood glucose levels or lifestyles. Studies have found that many people with undiagnosed diabetes already have complications such as chronic kidney disease and heart failure, retinopathy and neuropathy. 2 3 4
The costs associated with diabetes include increased use of health services, lost productivity, and disability which can be a considerable burden to the individual, to families and to society. When people have undiagnosed diabetes the opportunities and potential benefits of early diagnosis and treatment are lost. Furthermore, the costs related to undiagnosed diabetes are considerable. One study from the USA found that undiagnosed diabetes was responsible for an additional USD 18 billion in healthcare costs in one year. 5
Identification of people with diabetes
Opportunistic identification of people with risk factors for undiagnosed type 2 diabetes is feasible and cost effective. Risk scores and ‘tick tests’ listing risk factors for undiagnosed diabetes have been developed in many countries based on epidemiological surveys of the local populations and are widely available. While undiagnosed diabetes is a substantial problem, population-wide screening for diabetes is not appropriate. Countries must first develop health systems that can meet the needs of people living with diabetes. Priority should be given to providing good care and treatment to those already identified with diabetes, and targeted screening for those at high risk of undiagnosed diabetes may be considered once a working system for care is in place.
Estimating undiagnosed diabetes
Population-based studies provide the basis for estimating undiagnosed diabetes. A sample of people living in a particular area is tested for diabetes, which identifies both known and previously undiagnosed cases. The IDF Diabetes Atlas estimates undiagnosed diabetes using representative population-based studies reporting the proportion of undiagnosed cases. These findings from these studies are then combined by region and income group to generate an estimate that is later applied to the prevalence estimates for diabetes (Generating the numbers). Full details of the methods and results are available in the published paper at www.idf.org/diabetesatlas/papers.
1: Evaristo-Neto AD, Foss-Freitas MC, Foss MC. Prevalence of diabetes mellitus and impaired glucose tolerance in a rural community of Angola. Diabetol Metab Syndr 2010; 2: 63.
2: Plantinga LC, Crews DC, Coresh J, et al. Prevalence of chronic kidney disease in US adults with undiagnosed diabetes or prediabetes. Clin J Am Soc Nephrol 2010; 5 (4): 673-682.
3: Flores-Le Roux JA, Comin J, Pedro-Botet J, et al. Seven-year mortality in heart failure patients with undiagnosed diabetes: an observational study. Cardiovasc Diabetol 2011; 10: 39.
4: Spijkerman AMW, Dekker JM, Nijpels G, et al. Microvascular complications at time of diagnosis of type 2 diabetes are similar among diabetic patients detected by targeted screening and patients newly diagnosed in general practice: the hoorn screening study. Diabetes Care 2003; 26 (9): 2604-2608.
5: Agency for Healthcare Research and Quality. Treating Americans With Diabetes Cost Hospitals $83 Billion 2010. http://www.ahrq.gov/news/nn/nn081310.htm. [Accessed 2011-08-23]