A Target HbA1c Between 7 and 7.7% Reduces Microvascular and Macrovascular Events in T2D Regardless of Duration of Diabetes: a Meta-Analysis of Randomized Controlled Trials

Introduction: The target glycated haemoglobin (HbA1c) at which micro- and macrovascular benefits may be derived in type 2 diabetes (T2D) has never been clearly outlined. This meta-analysis was conducted on 15 randomized controlled trials to highlight the association of HbA1c range with outcomes.

Methods: The association of different HbA1c cluster (intention-to-treat (ITT) and end-of-study [EOS]) ranges (≤ 6.5%, 6.6-7.0%, 7.1-7.7%) with micro- and macrovascular complications and also the combined effect of T2D duration (< 10 years or ≥ 10 years) and HbA1c levels was assessed.

Results: An intensive glucose-lowering strategy resulted in a significant 17% (95% CI: 0.73-0.93, P < 0.01) reduction in retinopathy, 18% reduction in macroalbuminuria (95% CI 0.62-0.83, P < 0.01), 32% reduction in end-stage renal disease (ESRD) (95% CI 0.36-0.92, P = 0.02) and 13% reduction in non-fatal myocardial infarction (NFMI) (95% CI 0.78-0.96, P < 0.01). Based on HbA1c achieved at EOS, a significant 46% reduction in retinopathy, 52% reduction in macroalbuminuria, 36% reduction in (NFS) non-fatal stroke and a 22% reduction in all-cause mortality (ACM) were observed in the group with HbA1c in the 7.1-7.7% range. In the cohort, with diabetes duration ≥ 10 years, reduction of HbA1c to ≤ 7.0% and significant improvements in new-onset retinopathy (24%) and macroalbuminuria (30%) were offset by an increase in ACM (21%) and NFMI (17%).

Conclusion: Contrasting with most recommendations, this meta-analysis including recent studies suggests that the optimal HbA1c range for T2D is 7.1-7.7% regardless of diabetes duration.