Glycaemic control and macrovascular and microvascular outcomes: A systematic review and meta‐analysis of trials investigating intensive glucose‐lowering strategies in people with type 2 diabetes

AimWe aimed to determine the macrovascular and microvascular outcomes of intensive versus standard glucose‐lowering strategies in type 2 diabetes (T2D) and investigate the relationships between these outcomes and trial arm glycated haemoglobin (HbA1c) reduction.Materials and MethodsIn this systematic review and meta‐analysis, we identified relevant trials from MEDLINE, Embase, the Cochrane Library, and bibliographies up to August 2023. Macrovascular and microvascular outcomes, along with safety outcomes, were evaluated. Pooled study‐specific hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated, and meta‐regression was employed to analyse the relationships between outcomes and HbA1c reduction.ResultsWe included 11 unique RCTs involving 51 469 patients with T2D (intensive therapy, N = 26 691; standard therapy, N = 24 778). Intensive versus standard therapy reduced the risk of non‐fatal myocardial infarction (MI) (HR 0.84; 95% CI 0.75‐0.94) with no difference in the risk of major adverse cardiovascular events (HR 0.97; 95% CI 0.92‐1.03) and other adverse cardiovascular outcomes. Intensive versus standard therapy reduced the risk of retinopathy (HR 0.85; 0.78‐0.93), nephropathy (HR 0.71; 0.58‐0.87) and composite microvascular outcomes (HR 0.88; 0.77‐1.00). Meta‐regression analyses showed modest evidence of inverse linear relationships between HbA1c reduction and the outcomes of major adverse cardiovascular events, non‐fatal MI, stroke and retinopathy, but these were not statistically significant.ConclusionsIn people with T2D, intensive glucose control was associated with a reduced risk of non‐fatal MI and several microvascular outcomes, particularly retinopathy and nephropathy. The lack of an effect of intensive glucose‐lowering on most macrovascular outcomes calls for a more comprehensive approach to managing cardiovascular risk factors alongside glycaemic control.