Watershed years and events abound in medicine, and diabetes has been central to many of these defining moments. The identification of insulin in 1922 immediately made it possible to reduce the morbidity and mortality associated with the acute complications of hyperglycemia. However, proving the benefit of better glucose control on chronic microvascular and macrovascular complications has been more difficult.
Demonstration of the benefit of improved glycemic control on the microvascular target organs—the eyes, kidneys, and nerves—was presented in 2 large studies reported in the 1990s. In 1993, the Diabetes Control and Complications Trial (DCCT) provided evidence in a large cohort of patients with type 1 diabetes that intensive glucose control led to an approximate 60% reduction in the risk of disease progression in these organs.1 In 1998, the United Kingdom Prospective Diabetes Study (UKPDS) showed that 10 years of improved glucose control in patients with type 2 diabetes resulted in a 25% reduction in microvascular complications.2 Following publication of these 2 studies, the benefit of improved glucose control on microvascular disease was no longer a debate.