Diabetes
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Randomized Controlled Trial Multicenter Study Clinical Trial
The absence of a glycemic threshold for the development of long-term complications: the perspective of the Diabetes Control and Complications Trial.
The Diabetes Control and Complications Trial (DCCT) demonstrated a reduction in the development and progression of the long-term complications of IDDM with intensive therapy aimed at achieving glycemic control as close to the nondiabetic range as possible. The DCCT subsequently showed that the total lifetime exposure to glycemia was the principal determinant of the risk of retinopathy and that there was a continuous nonlinear relationship between this risk and the mean level of HbA1c (DCCT Research Group, Diabetes 44:968-993, 1995). In contrast, other authors, based on a retrospective study (Krolewski et al., N Engl J Med 332:1251-1255, 1995), have suggested that a glycemic threshold for microabuminuria and for retinopathy exists at an HbA1c level of approximately 8%, below which there is no further appreciable reduction in risk. ⋯ These extensive prospective DCCT data do not support the conjecture that a glycemic threshold for the development of complications exists at an HbA1c of 8% or that an HbA1c goal of 8% is maximally beneficial. In the DCCT, as HbA1c was reduced below 8% there were continuing relative reductions in the risk of complications, whereas there was a slower rate of increase in the risk of hypoglycemia. Therefore, the DCCT continues to recommend implementation of intensive therapy with the goal of achieving normal glycemia as early as possible in as many IDDM patients as is safely possible.