HbA1c variability and macrovascular benefits of intensive blood pressure control in patients with type 2 diabetes

Abstract Background Hypertension is the most common and manageable cardiovascular risk factor in patients with type 2 diabetes. However, the optimal target for blood pressure (BP) control in patients with type 2 diabetes remains a subject of debate. Purpose The aim of this study was to classify levels of haemoglobin A1c (HbA1c) variability using a machine learning algorithm and to investigate the impact of HbA1c variability on the effectiveness of intensive BP control. Methods Data from the Action to Control Cardiovascular Risk in Diabetes Blood Pressure (ACCORD-BP) trial were utilised. K-means clustering was utilised to group patients into three categories with low, medium, and high HbA1c variability levels, based on the HbA1c variability score and baseline HbA1c values. The primary outcome was a composite of non-fatal myocardial infarction (MI), stroke, or death from cardiovascular causes. The secondary outcome was all-cause mortality. Results In patients with low HbA1c variability rather than medium or high HbA1c variability, intensive BP control significantly reduced the risk of the primary outcome on a relative scale (HR: 0.60, 95%CI: 0.40-0.90, P interaction was 0.03), non-fatal MI (HR: 0.61, 95%CI: 0.37-1.00, P interaction was 0.04), and stroke (HR: 0.19, 95%CI: 0.05-0.64, P interaction was 0.02) or absolute scales. Regardless of the variability group, intensive BP control did not reduce the risk of cardiovascular death or all-cause mortality (P interaction > 0.05) both on relative and absolute risk scales. Conclusions Patients with type 2 diabetes who have low HbA1c variability may benefit from intensive BP control, particularly in significantly reducing the risk of non-fatal MI and stroke.