Adherence to Preventive Medications

Predictors and outcomes in the Diabetes Prevention Program

  1. Elizabeth A. Walker, DNSC, RN1,
  2. Mark Molitch, MD2,
  3. M. Kaye Kramer, BSN, MPH3,
  4. Steven Kahn, MB, CHB4,
  5. Yong Ma, MS5,
  6. Sharon Edelstein, SCM5,
  7. Kellie Smith, RN, MSN6,
  8. Mariana Kiefer Johnson, RN, MS2,
  9. Abbas Kitabchi, MD7,
  10. Jill Crandall, MD1 and
  11. for the Diabetes Prevention Program Research Group
  1. 1Diabetes Center, Albert Einstein College of Medicine, Bronx, New York
  2. 2Northwestern University, Evanston, Illinois
  3. 3University of Pittsburgh, Pittsburgh, Pennsylvania
  4. 4University of Washington, Seattle, Washington
  5. 5Diabetes Prevention Program Coordinating Center, George Washington University Biostatistics Center, Rockville, Maryland
  6. 6Thomas Jefferson University, Philadelphia, Pennsylvania
  7. 7University of Tennessee, Memphis, Tennessee
  1. Address correspondence and reprint requests to Dr. Elizabeth A.Walker, Diabetes Prevention Program, Coordinating Center, George Washington University Biostatistics Center, 6110 Executive Blvd. #750, Rockville, MD 20852. E-mail: dppmail{at}


OBJECTIVE—To evaluate barriers to and strategies for medication adherence and predictors of adherence and the primary outcome in the Diabetes Prevention Program (DPP).

RESEARCH DESIGN AND METHODS—Within a randomized, controlled primary prevention study for type 2 diabetes, we collected data on study medication adherence, its predictors, and health outcomes in 27 clinical centers across mainland U.S. and Hawaii. Medication arm participants included 2,155 adults with impaired glucose tolerance randomly assigned to either metformin or matched placebo treatment arms. Structured interviews were used to promote medication adherence and to collect data regarding adherence. Adherence was measured by pill count. The primary DPP outcome of type 2 diabetes was assessed by fasting plasma glucose and oral glucose tolerance test.

RESULTS—Older age-groups were more adherent than the youngest group (P = 0.01) in the metformin group. The most frequently reported barrier to adherence was “forgetting” (22%). Women reported more adverse effects of metformin (15 vs. 10%, P = 0.002) in the metformin group. Odds of nonadherence increased as participants reported more than one barrier (odds ratio 19.1, P < 0.001). Odds of adherence increased as participants reported multiple strategies to take medication (2.69, P < 0.0001). There was a 38.2% risk reduction for developing diabetes for those adherent to metformin compared with those adherent to placebo (P < 0.0003).

CONCLUSIONS—DPP medication adherence results are unique in primary prevention for a chronic disease in a large multiethnic sample. Our finding that adherence was associated with risk reduction for diabetes supports the development of brief interventions in clinical settings where medication adherence is a challenge.


  • A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances.

    The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C Section 1734 solely to indicate this fact.

    • Accepted June 6, 2006.
    • Received February 27, 2006.
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