Participant characteristics and study features associated with high retention rates in a longitudinal investigation of type 1 diabetes mellitus

Clin Trials. 2012 Dec;9(6):798-805. doi: 10.1177/1740774512458986. Epub 2012 Oct 1.


Background: The Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) Study has sustained an extraordinarily high level of participant involvement for over two decades.

Purpose: In order to identify specific characteristics of EDIC that contributed most strongly to retention, study-designed questionnaires were distributed to 1334 participants.

Methods: Confidential questionnaires were completed during EDIC Years 15-17. Participants were classified as Completely Adherent (completed all visits), Partly Adherent (missed >1 visit or major portion of a visit), or Inactive (did not participate for >5 years). Questionnaire items addressed specific aspects of clinic visits, evaluation procedures, staff-participant relationships, and medical/health-care support provided by EDIC.

Results: The most commonly cited reasons for continuing participation were Cutting Edge Tests to assess diabetes complications (79.3%), Annual Evaluations (67.7%), a desire to Help Others (65.2%), and Better Care for Diabetes (61.6%). Women chose Cutting Edge Tests as their first or second most important reason significantly more often than men, whereas men chose Better Care for Diabetes more frequently. Individuals with at least three diabetes-related complications were more likely than those with fewer complications to choose Annual Evaluations as their first or second reason for continued involvement.

Limitations: The small proportion of individuals who discontinued participation restricted our ability to identify factors associated with suspended involvement. In addition, our analysis is limited to a cohort with type 1 diabetes followed in an observational study after an average participation time of 6.5 years in a randomized trial.

Conclusions: The primary reasons identified by respondents for their long-term commitment are consistent with shorter-term studies and underscore the importance of expert medical care, supportive staff-participant relationships, and involvement with clinically and scientifically meaningful research.

Trial registration: NCT00360815 NCT00360893.

Publication types

  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Analysis of Variance
  • Diabetes Complications / diagnosis
  • Diabetes Complications / prevention & control
  • Diabetes Mellitus, Type 1 / complications
  • Diabetes Mellitus, Type 1 / drug therapy
  • Diabetes Mellitus, Type 1 / therapy*
  • Drug Administration Schedule
  • Drug Monitoring
  • Female
  • Follow-Up Studies
  • Humans
  • Hypoglycemic Agents / therapeutic use
  • Insulin / therapeutic use
  • Male
  • Middle Aged
  • Multivariate Analysis
  • Patient Compliance / psychology*
  • Patient Compliance / statistics & numerical data
  • Professional-Patient Relations
  • Surveys and Questionnaires
  • Young Adult


  • Hypoglycemic Agents
  • Insulin

Associated data