Relationship between improvement of glycaemic control and reduction of major cardiovascular events in 15 cardiovascular outcome trials: A meta-analysis with meta-regression

Aim In order to disclose relations between reduction of haemoglobin A1c (HbA1c) levels and risk of major cardiovascular events (MACE), we performed a meta-analysis with metaregression of all cardiovascular outcome trials (CVOTs) so far published in patients with type 2 diabetes (T2D). Materials and Methods An electronic search up to February 10, 2020 was conducted to determine eligible trials. Pooled summary estimates and 95% confidence intervals (CI) were calculated according to the random effects model using the Paule-Mandel method; restricted maximum likelihood estimators were used to estimate model parameters in the metaregression. Results The 15 CVOTs included evaluated 138,250 patients. In the pooled analysis, the risk of MACE was significantly reduced by 9% (hazard ratio, HR = 0.91, 0.87-0.95, P <0.001) as compared with placebo, with significant heterogeneity between trials (I-2 = 44%, P = 0.060) There was a robust relation between the reduction in achieved HbA1c at the end of the trial and the HR reduction for MACE (beta = -0.3169, P = 0.029), explaining most (78%) of the between-study variance; this relation was totally driven by the risk reduction of non-fatal stroke only, which explained 100% of between-study variance, and apparently restricted to the class of glucagon-like peptide 1 receptor agonists (GLP-1RAs). There was no relation between the reduction in achieved HbA1c and the HR for heart failure (variance explained = 0%) or all-cause mortality (variance explained = 6%). Conclusion The blood glucose reduction observed in CVOTs may play some role in reducing the risk of non-fatal stroke, at least during treatment with GLP-1RAs, without affecting the other two components of MACE.