How Much Evidence Do We Need to Change Practices in Which We Firmly Believe?

Should the glycosylated hemoglobin (HbA_1c) level goal in patients with long-standing type 2 diabetes be 7%? 6.5%? Lower? Although many clinicians believe in tight control for patients with type 2 diabetes, recent studies suggest that this practice is not beneficial. Several recently published commentaries cite evidence that challenges current beliefs and practices.

In the first major trial (done in the 1960s) of tight glucose control in patients with type 2 diabetes, oral glucose-lowering agents were associated with higher cardiovascular mortality and no differences in microvascular complications compared with placebo.1 Insulin also was not associated with clinical benefit.

In three recent large randomized trials (ACCORD,2 ADVANCE,3 and VADT4…