Cost-of-illness studies of diabetes mellitus: A systematic review

Background: Diabetes mellitus (DM) is recognised as a major health problem. Objectives: 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. Conclusion: 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.