Glycemic Control, Preexisting Cardiovascular Disease, and Risk of Major Cardiovascular Events in Patients with Type 2 Diabetes Mellitus: Systematic Review With Meta-Analysis of Cardiovascular Outcome Trials and Intensive Glucose Control Trials

Background-The value of glycemic control and preexisting cardiovascular disease in determining the risk of major cardiovascular events (MACE) in type 2 diabetes mellitus is uncertain. Intensive glucose control trials suggest that the 9% lower risk of MACE associated with intensive glycemic control, as compared with conventional glycemic control, is only driven by patients with type 2 diabetes mellitus without cardiovascular disease at baseline. Methods and Results-We did a meta-analysis of cardiovascular outcome trials dividing patients with or without preexisting cardiovascular disease; we found that the lower risk of MACE is confined to patients with cardiovascular disease at baseline. Compared with placebo, the use of both glucagon-like peptide-1 receptor agonists and sodium-glucose cotransporter-2 inhibitors was associated with a significant 14% lower MACE risk in patients with preexisting cardiovascular disease and with a nonsignificant 2% higher MACE risk in those without preexisting cardiovascular disease (P for interaction=0.021). The meta-regression analysis of all 12 trials demonstrated a significant (P=0.002) association between reductions of glycated hemoglobin in glycated hemoglobin A(1C). Accordingly, the reduction of MACE expected if all cardiovascular outcome trials had achieved a 0.9% glycated hemoglobin reduction would have been 33%. Routine clinical care data complement the results of cardiovascular outcome trials but with some differences: the lower risk of MACE with sodium-glucose cotransporter-2 inhibitor use is evident in patients with type 2 diabetes mellitus with or without preexisting cardiovascular disease. Conclusions-Sodium-glucose cotransporter-2 inhibitors and glucagon-like peptide-1 receptor agonists should be included in the therapeutic plan of patients with type 2 diabetes mellitus and overt cardiovascular disease, with due attention paid to improvement of glycemic control, which may amplify their benefit on MACE.