Self‐monitoring of blood glucose in type 2 diabetes mellitus: systematic review of economic evidence

Background Self‐monitoring of Blood Glucose (SMBG) is purported to improve glycaemic control, measured by glycosylated haemoglobin (HbA1c). The effectiveness of SMBG in type 2 diabetes mellitus (T2DM) is well‐documented though no systematic review of the economic evidence surrounding the use of SMBG in T2DM has been performed. Objectives To perform a systematic review of economic evaluations of SMBG in T2DM patients. Inclusion criteria All adult patients suffering from T2DM were included. Outcomes of differing treatment groups, where specified, were also recorded. Studies which examined SMBG as an intervention to control blood glucose were considered. To be included, studies must have made a formal attempt to relate cost to outcome data in a cost‐effectiveness or cost utility analysis. Types of outcomes The main outcomes were in terms of cost‐effectiveness and cost‐utility. Search strategy Extensive electronic searches were conducted. Searching was carried out, for the time period 1990 to January 2009, for full text papers and conference abstracts. Methodological quality Methodological quality of included studies was assessed by two reviewers using the standard critical appraisal tools from the JBI‐Actuari (Joanna Briggs Institute‐Analysis of Cost, Technology and Utilisation Assessment and Review Instrument). Included modelling studies were also assessed using the review criteria of economic models set out by Phillips and colleagues. Data collection Data from included studies were extracted using the JBI‐Actuari extraction tool. Data synthesis Studies were grouped by outcome measure and summarised using tabular and narrative formats. Results Five studies met the review criteria. Three were model‐based analyses assessing long‐term cost‐effectiveness of SMBG, all of which concluded that SMBG was cost‐effective. Two further primary economic evaluations assessed short‐term cost‐effectiveness. Their results found SMBG to be associated with increased cost and no significant reduction in HbA1c. The studies examined subgroups in terms of their treatment protocols and SMBG was considered more likely to be cost‐effective in drug and insulin treated groups compared to diet and exercise groups. Conclusions Economic evidence surrounding SMBG in T2DM remains unclear. For the most part, included studies found SMBG to be cost‐effective though analyses are extremely sensitive to relative effects, time‐frame of analyses and model assumptions. Whilst large uncertainty exists, SMBG may be cost‐effective in certain subgroups e.g. drug and insulin‐treated patients. Implication for practice No strong evidence to recommend the regular use of SMBG in well‐controlled diabetes patients, treated only with diet and exercise programmes, exists. The evidence does offer support for SMBG in drug and insulin treated T2DM. It is recommended that clinicians select appropriate patients for SMBG, from these groups, based on their domain expertise. Implications for research Large‐scale prospective RCTs of SMBG, particularly in drug and insulin treated patients, with well‐conducted economic evaluations performed alongside them, will enable a more accurate estimation of the cost‐effectiveness of SMBG. The optimal frequency and administration of SMBG is still unknown and is another area that warrants further research.