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October 2015

Long-term Contributions From the Diabetes Control and Complications Trial Cohort

Author Affiliations
  • 1currently in private practice, Waban, Massachusetts
  • 2National Eye Institute, Bethesda, Maryland
JAMA Ophthalmol. 2015;133(10):1107-1108. doi:10.1001/jamaophthalmol.2015.2735

The publication from the Diabetes Control and Complications Trial (DCCT) and Epidemiology of Diabetes Interventions and Complications (EDIC) study group1 continues to show differences by treatment groups that were randomly assigned 3 decades ago. This demonstrates how valuable the long-term follow-up of a clinical trial cohort can be, both for assessing treatment effects and the natural history of disease worsening.1 With the original DCCT study taking place so long ago, it is worthwhile to review where we were then and where we are now.2 It may be difficult to remember that prior to the DCCT results, there was great controversy as to whether tight blood glucose level control would reduce the secondary complications of diabetes mellitus, particularly, microvascular complications, including diabetic retinopathy. The DCCT investigators wrestled with how to randomly assign participants to different levels of blood glucose control in a large-scale multicenter clinical trial. They decided that specific control targets based on the newly available hemoglobin A1c (HgbA1c) test might be difficult to achieve in the intensive group while asking participants in the standard group to worsen their control to reach a specific level seemed unethical. The intensive group was instructed to use the newly available home glucose level monitoring, the most modern algorithms for multiple daily insulin injections, and insulin pumps for some participants to lower their HgbA1c levels as close as possible to the upper limit of normoglycemia. Most participants reached this level but, generally, this only could be maintained for limited amounts of time. Conventional therapy was focused on alleviating symptoms of diabetes mellitus, mainly signs of high or low blood glucose levels. Although testing urine was considered standard at that time, home glucose level monitoring was required for the intensive group at least 4 times daily. Conventionally treated patients were not encouraged to modify their regimens based on blood tests as long as they were asymptomatic. Both groups were encouraged to partake in an appropriate diabetic diet and received nutritional counseling.

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