[Proposal] The role of self-regulation in implicit food biases in people with type 1 diabetes

Background

Type 1 diabetes requires daily self-regulation to consistently manage glycaemic control [1]. Significant emphasis is necessitated to be placed on food in type 1 diabetes management, particularly food high in carbohydrates, as the intake of carbohydrates must be compensated by the self-administration of insulin or else blood sugar will rise. This emphasis on food could suggest why people with type 1 diabetes are more likely than their peers to suffer with disordered eating and eating disorders [2]. Some research has indicated the role of depleted self-regulatory capacity in decreased condition management in type 1 diabetes [3], including those with eating disorders [4]. This study will look to assess the role of perceived self-regulatory capacity on implicit food biases, particularly foods high in carbohydrates, and assess differences in these biases between people with type 1 diabetes and controls. However, to our knowledge, this is the first study looking to evaluate the role of self-regulation on implicit food biases in a type 1 diabetes population.

Our hypotheses for this study are as follows:

  • People with type 1 diabetes will demonstrate a greater negative bias towards high-carbohydrate food, as measured through longer reaction times and greater errors in the high-carbohydrate/positive, and low-carbohydrate/negative conditions, regardless of how healthy the foods are.
  • This effect will be larger in people with type 1 diabetes who demonstrate impaired self-regulatory capacity, compared to those with intact capacity.

The results of this research will help to further our understanding of the role self-regulation plays in food biases among people with type 1 diabetes, allowing us to greater appreciate the increased incidences of eating disorders in the population and begin to develop appropriate educational interventions.

Methodology

A pilot study will first be conducted to categorise a selection of 40 stock photograph stimuli into the following: high- vs low-carbohydrate, and healthy vs unhealthy. This pilot will run in questionnaire format and be hosted on Qualtrics. It will require participants to look at one food photograph per page, deciding if the food is high- or low-carbohydrate, and healthy or unhealthy. We anticipate that 10 photographs will be sorted into each category (high-carbohydrate/healthy; high-carbohydrate/unhealthy; low-carbohydrate/healthy; low-carbohydrate/unhealthy).

Participants will then take part in an evaluative priming task, in which they will be presented with a priming photograph, and will then be asked to evaluate a word stimulus as either positive or negative. The priming stimuli will be the 40 stock photograph stimuli categorised in the pilot study. There will four levels: high-carbohydrate/healthy food (e.g. brown rice), high-carbohydrate/unhealthy food (e.g. sweets), low-carbohydrate/healthy food (e.g. cucumber), and low-carbohydrate/unhealthy food (e.g. cheese). The target stimuli will include 40 words derived from SentiWords, which categorised words on a polarity scale between -1 (very negative) and +1 (very positive). Negative words will be selected with polarity scores of <-.7, and positive words will be selected with polarity scores of >.7. Words will be pre-screened for differences in length.

This task will be created using PsychPy. For any given trial, the prime will be presented for 250ms, there will be an interstimulus interval of 50ms, then the target word will be displayed until participants respond. A total of 160 trials will take place in the main study, allowing for all 40 words to be assessed in relation to each of the 4 levels of photographs.

Sample Size & Study Costs

The pilot study recruit 40 general population participants to take part in this pilot, in accordance with Cohen’s recommendation of the population of each cell being greater than 5. We anticipate the study will take approximately 10 minutes. In accordance with Prolific’s fair rate of pay, participants will receive £1.25 for their contribution. The total cost for this pilot is £70.

The main study will recruit 190 participants, 95 with type 1 diabetes, and 95 controls. This is based on the sample size calculation from G*Power (effect size f=.25, α err prob=.05, power=.8, numerator df=2, number of groups = 6 , minimum sample size=158), plus the addition of an extra 20% to account for outliers. We anticipate this study to take approximately 60 minutes. In accordance with Prolific’s fair rate of pay, participants will receive £7.50 for their contribution. The total cost for this pilot is £1995. The cost for the combined studies is therefore £2065.

Preregistration & Open Science

This study will be preregistered on AsPredicted imminently. All materials used in the study, as well as the data obtained will be made openly available on the Lancaster University PURE database, with a Creative Commons Attribution Licence 4.0.

References

[1] Hood, K. K., Peterson, C. M., Rohan, J. M., & Drotar, D. (2009). Association between adherence and glycemic control in pediatric type 1 diabetes: a meta-analysis. Pediatrics , 124 (6), e1171-e1179.

[2] Colton, P., Olmsted, M., Daneman, D., Rydall, A., & Rodin, G. (2004). Disturbed eating behavior and eating disorders in preteen and early teenage girls with type 1 diabetes: a case-controlled study. Diabetes care , 27 (7), 1654-1659.

[3] Berg, C. A., Wiebe, D. J., Suchy, Y., Hughes, A. E., Anderson, J. H., Godbey, E. I., … & White, P. C. (2014). Individual differences and day-to-day fluctuations in perceived self-regulation associated with daily adherence in late adolescents with type 1 diabetes. Journal of Pediatric Psychology , 39 (9), 1038-1048.

[4] Grylli, V., Wagner, G., Berger, G., Sinnreich, U., Schober, E., & Karwautz, A. (2010). Characteristics of self‐regulation in adolescent girls with Type 1 diabetes with and without eating disorders: A cross‐sectional study. Psychology and Psychotherapy: Theory, Research and Practice , 83 (3), 289-301.