title: Cost-of-illness studies of diabetes mellitus: a systematic review.
abstract: BACKGROUND
  Diabetes mellitus (DM) is recognised as a major health problem.
  
  
  OBJECTIVE
  The aims of this study are two-fold: (1) to describe the methods used in the identified cost-of-illness (COI) studies of DM and (2) to summarise their study findings regarding the economic impact of DM.
  
  
  METHODS
  This is a systematic review of MEDLINE and Scopus journal articles reporting the cost of type 1 and/or 2 DM that were published in English from 2007 to 2011. Costs reported in the included studies were converted to US dollars.
  
  
  RESULTS
  The systematic search yielded 30 articles. The studies varied considerably in their study design, perspective and included cost categories. Estimates for the total annual costs of DM ranged from US$141.6 million to US$174 billion; direct costs ranged from US$150 to US$14,060 per patient per year (pppy) whereas indirect costs ranged from US$39.6 to US$7,164 pppy. Inpatient cost was the major contributor to direct cost in half of the studies that included inpatient costs, physician services and medications.
  
  
  CONCLUSIONS
  There is a considerable economic burden associated with DM. Future research should focus on improving methods of estimating costs, enhancing the interpretation of study findings and facilitating comparisons between studies.
authors.affiliation: Department of Pharmacy, Faculty of Science, National University of Singapore, Singapore, Singapore.
authors.forename: Charmaine S
authors.initials: CS
authors.lastname: Ng
authors.affiliation: Department of Pharmacy, Faculty of Science, National University of Singapore, Singapore, Singapore.
authors.forename: Joyce Y C
authors.initials: JY
authors.lastname: Lee
authors.affiliation: Information Management, Corporate Development, National Healthcare Group, Singapore, Singapore; Saw Swee Hock School of Public Health, National University of Singapore and National University Health System, Singapore, Singapore.
authors.forename: Matthias Phs
authors.initials: MP
authors.lastname: Toh
authors.affiliation: Department of Pharmacy, Faculty of Science, National University of Singapore, Singapore, Singapore. Electronic address: nancykotw@gmail.com.
authors.forename: Yu
authors.initials: Y
authors.lastname: Ko
mesh_terms: D017281:Cost of Illness; D003920:Diabetes Mellitus / Q000191:economics*; D017048:Health Care Costs / Q000639:trends*; D006801:Humans
keywords: Cost analysis; Cost of disease; Cost-of-illness; Diabetes; Economic burden; Healthcare costs