Patients under study originally participated in the DCCT, a recently concluded NIKKD clinical trial that demonstrated dramatic reductions in microvascular complications with intensive glucose control. The DCCT, conducted from 1983 to 1993 in 1,441 insulin dependent diabetes mellitus subjects at 209 medical centers, showed that keeping blood sugar levels as close to normal as possible slows the onset and progression of eye, kidney, and nerve diseases cause by diabetes.