Evidence:

• Five randomized controlled trials have compared health outcomes in groups of patients with type 2 diabetes that differ with respect to glycemic control (77; 78; 79; 80; 81; 82; 83; 84; 85; 86; 87). Four of these studies were small and lacked power to detect clinically important differences between groups (79; 80; 81; 82; 83; 84; 85; 86; 87).
• Two of these smaller studies found reductions in progression of albuminuria and retinopathy with tight glycemic control (85; 87), and one study that included tight glycemic control as part of a multifactorial intervention found a significant reduction in severe visual impairment (83).
• The UKPDS was the longest and largest study, with 3867 UK residents with newly diagnosed type 2 diabetes randomly assigned to intensive vs. conventional glycemic control (77; 78).
• After 10 years of follow-up in the UKPDS, there was a significant reduction in microvascular complications with tight glycemic control (average HbA_1c 7.0% vs. 7.9%), but the benefit was almost entirely due to a reduction in need for retinal photocoagulation. Furthermore, the intervention was not blinded; therefore, outcomes that involved clinical judgment could have been biased (77).
• The primary UKPDS analysis found a nonsignificant trend toward a reduction in MI in the group with tight glycemic control (relative risk, 0.84 [CI, 0.71 to 1.0], P = 0.052), and found no benefit on mortality rates, progression to renal failure, loss of vision, amputation, stroke, or quality of life (77).
• It should be noted that all of these studies were conducted in patients with clinically diagnosed diabetes, and only 31.2% of patients in the UKPDS were diagnosed at an asymptomatic stage (through opportunistic testing) (88).

Comments:

• None.