Effect of Prior Intensive Therapy in Type 1 Diabetes Mellitus on 10-year Progression of Retinopathy in the DCCT/EDIC: Comparison of Adults and Adolescents

  1. Neil H. White (White_N{at},
  2. Wanjie Sun2,
  3. Patricia A. Cleary2,
  4. William V. Tamborlane3,
  5. Ronald P. Danis4,
  6. Dean P. Hainsworth5 and
  7. Matthew D. Davis4
  1. 1. Washington University, Saint Louis, Missouri
  2. 2. The George Washington University, The Biostatistics Center, Rockville, Maryland
  3. 3. Yale University, School of Medicine, New Haven, Connecticut
  4. 4. University of Wisconsin – Madison, Madison, Wisconsin
  5. 5. University of Missouri, Columbia, Missouri


Objective: To examine differences between adolescents and adults in persistence of the benefits of intensive therapy 10 years after completion of the Diabetes Control and Complications Trial (DCCT).

Methods: During the Epidemiology of Diabetes Interventions and Complications (EDIC) study, progression of retinopathy from DCCT closeout to EDIC year 10 was evaluated in 1,055 adults and 156 adolescents.

Results: During 10 years of follow-up, glycosylated hemoglobin (HbA1c) was similar between the original intensive (IT) and conventional (CON) groups and between the former adolescents and adults. At EDIC year 10, adults in the former IT group continued to show slower progression of diabetic retinopathy than those in the CON group (adjusted hazard reduction (HR): 57%, P<.0001); whereas in adolescents this beneficial effect had disappeared (adjusted HR: 32%, P=.13). Seventy-nine percent of observed differences in the prolonged treatment effect between adults and adolescents at year 10 were explained by differences in mean HbA1c during DCCT between adolescents and adults (8.9% vs 8.1%), particularly between IT adolescents and IT adults (8.1% vs. 7.2%).

Conclusion: Prior glycemic control during DCCT is vital for the persistence of the beneficial effects of IT therapy ten years later. Lowering HbA1c to as close to normal as safely possible without severe hypoglycemia and starting as early as possible should be attempted for all subjects with type 1 diabetes. These results underscore the importance of maintaining HbA1c at target values for as long as possible since the benefits of former IT treatment wane over time if HbA1c levels rise.


    • Received August 14, 2009.
    • Accepted February 1, 2010.