Objective: Fibrinogen is a key mediator of thrombosis and it has been implicated in the pathogenesis of
atherosclerosis. Because metformin has shown a potential protective effect on different atherothrombotic risk
factors, we assessed in this meta-analysis its effect on plasma fibrinogen concentrations.
Methods: A systematic review and meta-analysis was carried out to identify randomized placebo-controlled trials
evaluating the effect of metformin administration on fibrinogen levels. The search included PubMed-Medline,
Scopus, ISI Web of Knowledge and Google Scholar databases (by June 2, 2017) and quality of studies was performed
according to Cochrane criteria. Quantitative data synthesis was conducted using a random-effects model
and sensitivity analysis by the leave-one-out method. Meta-regression analysis was performed to assess the modifiers
of treatment response.
Results: Meta-analysis of data from 9 randomized placebo-controlled clinical trials with 2302 patients comprising
10 treatment arms did not suggest a significant change in plasma fibrinogen concentrations following metformin
therapy (WMD: -0.25 g/L, 95% CI: -0.53, 0.04, p = 0.092). The effect size was robust in the leave-one-out sensitivity
analysis and remained non-significant after omission of each single study from the meta-analysis.
Conclusion: No significant effect of metformin on plasma fibrinogen concentrations was demonstrated in the