Assessing the psychometric properties of the diabetes illness perception questionnaire and the diabetes illness representation questionnaire for adults with and without ID

Aim: This study compares the psychometric properties of the Diabetes Illness Perception Questionnaire (DIPQ) and Diabetes Illness Representation Questionnaire (DIRQ) in adults with and without ID. Method: Semi-structured interviews were conducted with 188 adults with ID and compared with 755 adults without ID: both with type 2 diabetes across the UK. Statistical analyses were performed to test the psychometric properties of the DIPQ and DIRQ and to examine if there were any mean differences across samples. Results: The factor structure was found to hold for the DIPQ (participants' illness coherence score, perception of the duration of their illness and the perception of their ability to affect the course of their diabetes) for both the adults with and without ID. However, the factor structure was found to be poor for both the adults with and without ID for the DIRQ (participants' perceived seriousness of condition and the perceived impact of diabetes). Conclusions: The DIPQ questionnaire can be used as a secondary outcome measure. Caution must be taken with the DIRQ.