Reducing the health risks of diabetes: how self-determination theory may help improve medication adherence and quality of life

Abstract

Purpose: The purpose of this study is to apply the self-determination theory (SDT) model of health behavior to predict medication adherence, quality of life, and physiological outcomes among patients with diabetes.

Methods: Patients with diabetes (N = 2973) receiving care from an integrated health care delivery system in 2003 and 2004 were identified from automated databases and invited to participate in this study. In 2005, patients responded to a mixed telephone-and-mail survey assessing perceived autonomy support from health care providers, autonomous self-regulation for medication use, perceived competence for diabetes self-management, medication adherence, and quality of life. In 2006, pharmacy claims data were used to indicate medication adherence, and patients' non-high-density lipoprotein (HDL) cholesterol, A1C, and glucose levels were assessed.

Results: The SDT model of health behavior provided adequate fit to the data. As hypothesized, perceived autonomy support from health care providers related positively to autonomous self-regulation for medication use, which in turn related positively to perceived competence for diabetes self-management. Perceived competence then related positively to quality of life and medication adherence, and the latter construct related negatively to non-HDL cholesterol, A1C, and glucose levels.

Conclusions: Health care providers' support for patients' autonomy and competence around medication use and diabetes self-management related positively to medication adherence, quality of life, and physiological outcomes among patients with diabetes.

Figure 1

The structural equation model, with parameter estimates, examining the structural relations among the self-determination theory model of health behavior, quality of life, medication adherence, and physiological outcomes among patients with diabetes. Notes. Latent variables were used to represent Medication Adherence and Glycemic Control, and the path coefficients are standardized estimates. Each squared multiple correlation (R²) value represents the proportion of variance in an endogenous variable that is explained by the predictors of that particular endogenous variable. The covariances (specified in the text) between the residual variances were omitted from the figure for clarity. DP = Pharmacy-report anti-diabetic medication, CP = Pharmacy-report lipid-lowering medication, DS = Self-report anti-diabetic medication, CS = Self-report lipid-lowering medication, HbA1c = glycosylated hemoglobin. ***p < .001