Illness perceptions and glycaemic control in diabetes: a systematic review with meta-analysis

Aims: The Illness Perception Questionnaire, the Revised Illness Perception Questionnaire and the Brief Illness Perception Questionnaire have been widely used to measure people's beliefs about diabetes. This review aimed to synthesize evidence on the relationship between the dimensions of the Illness Perception Questionnaire, the Revised Illness Perception Questionnaire and the Brief Illness Perception Questionnaire and HbA(1c) level in adults with diabetes.Methods: A systematic literature search was carried out in January 2010 to identify relevant studies. Random-effects model meta-analyses were conducted with cross-sectional data to quantify the relationship between Illness Perception Questionnaire dimensions and HbA(1c) across studies. Randomized controlled trials that targeted Illness Perception Questionnaire perceptions and included HbA(1c) as an outcome measure were discussed in a narrative review.Results: Nine cross-sectional studies and four randomized controlled trials were included. Stronger Identity (r+=0.14), Consequences (r+=0.14), Timeline Cyclical (r+ = 0.26) Concern (r+= 0.21), and Emotional Representations (r+=0.18) perceptions had significant positive associations with HbA(1c.) Greater Personal Control (r+=- 0.12) was negatively associated with HbA(1c) . For all relationships, heterogeneity tests were non-significant, suggesting little variability in effect size estimates. Two of the four randomized controlled trials successfully changed illness perceptions, with one also reporting an intervention group reduction in HbA(1c).Conclusions: Some Illness Perception Questionnaire dimensions had small significant associations with HbA(1c) , although the direction of these associations remains unclear. There was also tentative evidence that illness perceptions can be positively changed through targeted intervention and that these changes may also impact on glycaemic control. Future research could benefit from tailoring intervention content to perceptions that are most highly associated with HbA(1c).