VALIDATION AND RELIABILITY OF A GUIDED QUESTIONNAIRE (GQ) FOR TYPE 1 DIABETES MELLITUS (T1DM) CHILDREN AND PARENTS ON PERIODONTAL DISEASE (PD) The prevalence of PD is notably high in individuals with T1DM. Despite this, there is a limited availability of research on the utilization of questionnaires to evaluate self-perceived PD, patient knowledge, and their perception of PD in T1DM patients. Therefore, our objective was to establish validity and reliability of a bilingual (English-Malay) version of the guided questionnaire (GQ) to be used among pediatric T1DM patients attending Universiti Teknologi MARA (UiTM) Sungai Buloh campus and the Universiti Malaya (UM). This questionnaire focused on self-reported periodontal disease (PD), assessing their knowledge, and understanding of the bidirectional relationship between PD and T1DM. The dual-language GQ was adapted from the Self-Reported Questionnaire Malay Modified (SRQMM) to suit the targeted participants. Content validation was carried out among five field experts, and face validation was done among pediatric patients in Dental Faculty UiTM. Reliability testing was administered in T1DM patients attending UiTM and UM. The structure and words of the component in GQ were modified to ensure that it was appropriate for the participants. The item-level Content Validity Index (I-CVI) turned out to be valid with an average of 0.98. The subjective measurement of face validation showed satisfactory results after the second revision. Reliability concerning Cronbach’s alpha (α) values was computed relying on all 21 items, which were acceptable at about 0.777, 0.644, 0.780 in the self-perceived PD assessment domain, knowledge domain and perception domain, respectively. Hence, the adapted dual language paediatrics version of the GQ is a reliable and valid tool for assessing self-perceived PD, knowledge, and perception in T1DM patients on PD and it can be effectively utilized by non-dental healthcare personnel.