Evaluation of the transtheoretical model with regard to eating - Diabetes - Author Abstract

Nutrition Research Newsletter, June, 2003

Behavioral self-care has long been important in managing diabetes, due to the complex, modifiable factors involved. To achieve optimal blood glucose control, an individual must engage in a number of behaviors consistently and throughout his or her lifetime. Unless individuals are in a motivated state of mind, traditional action-oriented interventions with the help of healthcare professionals do not work. The Transtheoretical Model (TTM) of behavior change has been effective to those interested in enhancing motivation for self-care. This model is comprised of five distinct motivation stages: precontemplation; contemplation; preparation; action and maintenance. Individuals in the first three stages are considered to be in the preaction stages, whereas those in the last two stages are considered to be in the action stages. Currently, there is little research validating this model for healthy eating in individuals with diabetes.

In a recent study, researchers examined the relationship of stages of change for healthy, low-fat eating in overweight diabetic individuals to demographic variables, eating-related factors, healthcare utilization, and psychosocial factors. The data were obtained from a large randomized clinical trial titled Diabetes Stages of Change. The intervention, called Pathways to Change Diabetes (PTC), was based on the TTM and was compared to treatment as usual (TAU). The design was a multifactorial split-plot, with two randomized among-subjects factors: treatment (PTC and TAU) and strips (free strips and no strips) and one within-subject factor (pre- and post-treatment). Participants were stratified into insulin oral agents only groups and then randomized into PTC/TAU and free test strips/no strips groups.

Subjects included 768 obese individuals who were staged on readiness to adopt a healthy, low-fat diet. All subjects had a BMI greater than or equal to 27 kg/[m.sup.2] and had either type-1 or type-2 diabetes. Subjects received a full assessment at intake and at 1-year follow-up. These assessments included biomedical evaluation (Hb[A.sub.1c], serum blood glucose, lipids [total, HDL, and LDL cholesterol and triglycerides], and BMI), psychosocial functioning, healthcare utilization, and TTM constructs for healthy eating. The TTM constructs for each target behavior were assessed at intake and quarterly. An expert/system-generated, individualized report that provided stage-matched feedback on the processes of change, pros and cons, situational temptations, and additional strategies to help facilitate movement through the stages was produced and provided to the subjects. Additionally, stage-matched phone counseling was provided quarterly. Finally, PTC participants received regular stage-based newsletters focusing on dietary issues.

The independent variable in this study was the stage of readiness to adopt healthy, low-fat eating habits. The dependant variables were grouped into four categories: demographic, eating-related, healthcare utilization, and psychosocial factors.

Stage-based differences were observed for type-1 diabetic participants on percent of calories from fat and number of daily vegetable servings. For type-2 diabetic subjects, sex, disease-specific quality of life, percent calories from fat, and number of daily vegetable servings differed across stages. Those individuals found to be in the action stages were more likely to be female and have a better quality of life and healthier eating habits. Type-2 diabetic insulin-requiting subjects in action stages were more likely to be married. Social support was highest for those in the contemplation stage and lowest for those subjects in the action stage. Type-2 diabetic individuals on oral therapy in the action stages were older, had a lower BMI, ate more fruit, were nonsmokers, recently attended diabetes education, had a better quality of life and social support, and had less stress. There was one anomalous finding for type-2 diabetic subjects: individuals in the pre-contemplation stage scored similarly to those in the action stages.

The investigators feel that these data validate the TTM, as those in the action stages displayed healthier eating. They also note that individuals in the precontemplation stage are a heterogeneous group and may need individually tailored interventions.

M. Vallis, L. Ruggiero, G. Greene, et al, Stages of change for healthy eating in diabetes. Diabetes Care (26, 1468-1474, May, 2003). Correspondence: Michael Vallis, PhD., Diabetes Management Centre, Room 330, Bethune Bldg., Queen Elizabeth II Health Sciences Centre, 1278 Tower Rd., Halifax, Nova Scotia B3H 2Y9, Canada. E-mail: tvallis@is.dal.ca