Background and aim: In patients with type 2 diabetes mellitus, the relationship between lowering glycated hemoglobin (HbA(1c)) and macrovascular complications is not clear and therefore lowering the level of HbA(1c) is controversial.
Methods and results: We searched for all randomized controlled trials comparing the effects of intensive and standard glycemic control on vascular events in patients with type 2 diabetes mellitus. The primary endpoint was combined macrovascular complications, including cardiac events, stroke and peripheral vascular disease. Fixed and random effect models were used to analyze the results. Eight studies were included according to selection criteria. The results showed no benefits of intensive glycemic control on macrovascular and microvascular complications (P>0.1), but a higher rate of severe hypoglycemia (P<0.00001) in the intensive control group when the target HbA(1c) level was <7.0%. When the target HbA(1c) level was lowered to 7.0-7.9%, intensive glycemic control showed benefits on the reduction of microvascular events (P<0.05) without increasing the risk of severe hypoglycemia (P=0.74), but no influence on macrovascular complications (P>0.1).
Conclusion: The results of this analysis suggest that a target HbA(1c) level of 7.0-7.9% may be a better glycemic control target than that of <7.0% in patients with established type 2 diabetes mellitus.