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 (I2 = 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.