Effects of intensive blood pressure reduction on myocardial infarction and stroke in diabetes: a meta-analysis in 73 913 patients

OBJECTIVE: Guidelines generally recommend intensive lowering of blood pressure (BP) in patients with type 2 diabetes. There is uncertainty about the impact of this strategy on case-specific events. Thus, we generated estimates of the effects of BP reduction on the risk of myocardial infarction (MI) and stroke in diabetic patients. METHODS: We selected studies which compared different BP-lowering agents and different BP intervention strategies in patients with diabetes. Outcome measures were MI and stroke. We abstracted information about study design, intervention, population, outcomes, and methodological quality for a total of 73,913 patients with diabetes (295,652 patient-years of exposure) randomized in 31 intervention trials. RESULTS: Overall, experimental treatment reduced the risk of stroke by 9% (P = 0.0059), and that of MI by 11% (P = 0.0015). Allocation to more-tight, compared with less-tight, BP control reduced the risk of stroke by 31% relative risk (RR) 0.61, 95% confidence interval (CI) 0.48-0.79, whereas the reduction in the risk of MI approached, but did not achieve, significance odds ratio (OR) 0.87, 95% CI 0.74-1.02. In a meta-regression analysis, the risk of stroke decreased by 13% (95% CI 5-20, P = 0.002) for each 5-mmHg reduction in SBP, and by 11.5% (95% CI 5-17, P < 0.001) for each 2-mmHg reduction in DBP. In contrast, the risk of MI did not show any association with the extent of BP reduction (SBP: P = 0.793; DBP: P = 0.832). CONCLUSION: In patients with diabetes, protection from stroke increases with the magnitude of BP reduction. We were unable to detect such a relation for MI.