title: Global estimates of undiagnosed diabetes in adults.
abstract: OBJECTIVE
  The prevalence of diabetes is rapidly increasing worldwide. Type 2 diabetes may remain undetected for many years, leading to severe complications and healthcare costs. This paper provides estimates of the prevalence of undiagnosed diabetes mellitus (UDM), using available data from high quality representative population-based sources.
  
  
  METHODS
  Data sources reporting both diagnosed and previously undiagnosed diabetes were identified and selected according to previously described IDF methodology for diabetes in adults (aged 20-79). Countries were divided into 15 data regions based on their geographic IDF Region and World Bank income classification. The median UDM proportion was calculated from selected data sources for each of data region. The number of UDM cases in 2013 was calculated from country, age and sex-specific estimates of known diabetes cases and data region-specific UDM proportion.
  
  
  RESULTS
  Of 744 reviewed data sources, 88 sources representing 74 countries had sufficient information and were selected for generation of estimates of UDM. Globally, 45.8%, or 174.8 million of all diabetes cases in adults are estimated to be undiagnosed, ranging from 24.1% to 75.1% across data regions. An estimated 83.8% of all cases of UDM are in low- and middle-income countries. At a country level, Pacific Island nations have the highest prevalence of UDM.
  
  
  CONCLUSIONS
  There is a high proportion of UDM globally, and especially in developing countries. Further high-quality studies of UDM are needed to strengthen future estimates.
authors.affiliation: International Diabetes Federation, Brussels, Belgium. Electronic address: jessica.beagley@oxon.org.
authors.forename: Jessica
authors.initials: J
authors.lastname: Beagley
authors.affiliation: International Diabetes Federation, Brussels, Belgium.
authors.forename: Leonor
authors.initials: L
authors.lastname: Guariguata
authors.affiliation: International Diabetes Federation, Brussels, Belgium.
authors.forename: Clara
authors.initials: C
authors.lastname: Weil
authors.affiliation: Department of Diabetes and Endocrinology, School of Clinical Medicine, University of KwaZulu-Natal, Durban South Africa.
authors.forename: Ayesha A
authors.initials: AA
authors.lastname: Motala
mesh_terms: D000328:Adult; D000368:Aged; D003906:Developing Countries; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis* / Q000453:epidemiology*; D005260:Female; D014943:Global Health / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D055815:Young Adult
keywords: Epidemiology; Health systems; Prevalence; Type 2 diabetes; Undiagnosed diabetes