The development of self-efficacy and outcome expectation measures regarding glycaemic load and the nutritional management of type 2 diabetes

OBJECTIVE: Traditionally, carbohydrate has been the largest contributor to energy intake among people with diabetes, yet different carbohydrate foods produce different glycaemic responses. Glycaemic load represents the total glycaemic effect of the diet and influences glycaemic control. Adequate self-efficacy and outcome expectations are needed to change carbohydrate intake and to evaluate relevant interventions. The purpose of this research was to develop and test instruments regarding self-efficacy and outcome expectations for the adoption of a lower glycaemic load diet. DESIGN: Participants completed each instrument at their convenience and mailed the instruments to the investigators. SETTING/SUBJECTS: A community sample of individuals 21-75 years of age with type 2 diabetes for >or= 1 year (n = 108) was recruited. RESULTS: Principal components analysis revealed three factors on the self-efficacy questionnaire: glycaemic index, negative food selection and self-regulation efficacy which accounted for 62% of the variance in these items. The outcome expectations instrument yielded three factors: barriers to dietary change and glycaemic control, and family support expectations which accounted for 48% of the variance. Coefficient alpha for each construct was >0.70 and coefficient H for each construct was >or= 0.80. CONCLUSIONS: The two instruments developed for this study can provide important insights about the self-efficacy and outcome expectations regarding the quantity and quality of carbohydrate consumed and self-monitoring performed for diabetes management. Future research is needed to evaluate the relationship among these constructs, dietary intake and glycaemic control.