Increasing the use of electronic health records could hold the key to determining whether metformin reduces the risk of cardiovascular disease among people with type 2 diabetes, according to new research.
Metformin is the most-prescribed oral medication to lower blood glucose worldwide. Yet previous systematic reviews have raised doubts about its effectiveness in reducing the risk of cardiovascular disease, the most costly complication of type 2 diabetes.
Researchers from the School of Clinical Medicine at the University of Cambridge carried out a study to systematically identify and pool randomised trials reporting cardiovascular outcomes in which the effect of metformin was ‘isolated’ through comparison to diet, lifestyle or placebo.
The study saw the researchers perform an electronic literature search of MEDLINE, EMBASE and the Cochrane Library, manually screening the reference lists of previous meta-analyses of trials of metformin identified through a MEDLINE search.
The team included randomised controlled trials of adults with type 2 diabetes comparing any dose and preparation of oral metformin with no intervention, placebo or a lifestyle intervention and reporting mortality or a cardiovascular outcome.
The results, published in Diabetologia, are based on 10 articles reporting 13 trials (including a total of 2,079 individuals with type 2 diabetes allocated to metformin and a similar number to comparison groups) of which only four compared metformin with placebo and collected data on cardiovascular outcomes.
Researchers said: “There remains uncertainty about whether metformin reduces risk of cardiovascular disease among patients with type 2 diabetes, for whom it is the recommended first-line drug. Although this is mainly due to
“Although this is mainly due to absence of evidence, it is unlikely that a definitive placebo-controlled cardiovascular endpoint trial among people with diabetes will be forthcoming.
“Alternative approaches to reduce the uncertainty include the use of electronic health records in long-term pragmatic evaluations, inclusion of metformin in factorial trials, publication of cardiovascular outcome data from adverse event reporting in trials of metformin and a cardiovascular endpoint trial of metformin among people without diabetes.”