Oral Health-Related Quality of Life, Behaviours and Oral Manifestations in a Paediatric Population with Type I Diabetes Mellitus: A Comparative Cross-Sectional Study

<b>Introduction:</b> Type 1 diabetes mellitus (DM1) can influence oral health, increasing susceptibility to various oral manifestations. <b>Objectives:</b> This study aimed to characterise oral health-related quality of life (OHRQoL), reported oral symptoms, and oral health behaviours in paediatric individuals with DM1, and compare them with those without DM1; as well as to identify factors associated with OHRQoL in both groups. <b>Methods:</b> A cross-sectional study was conducted using an online questionnaire completed by caregivers of Portuguese children with or without DM1. The questionnaire collected information on sociodemographic, oral health behaviours, perceived oral health, reported oral manifestations, and OHRQoL using the Early Childhood Oral Health Impact Scale (ECOHIS). Descriptive statistics were calculated, along with chi-square tests and negative binomial regression analyses (α = 0.05). <b>Results:</b> The sample included 235 individuals (115 with DM1 and 120 without). No significant differences were observed in overall OHRQoL between the groups, although children with DM1 had slightly higher ECOHIS total scores (4.38 vs. 4.02). Oral health behaviours were comparable in both groups. Children with DM1 reported significantly more xerostomia (<i>p</i> < 0.001). Within the DM1 group, better OHRQoL was significantly related to the following variables: female sex, absence of caries, absence of gingivitis, and no taste changes. In contrast, in the non-DM1 group, OHRQoL was associated with different conditions: the caregiver perception, frequent sugar intake, recurrent aphthous stomatitis, burning mouth sensations, and age. <b>Conclusion:</b> Although OHRQoL levels and oral health behaviours were similar between children with and without DM1, the factors influencing these outcomes varied considerably, emphasising the need for targeted oral health strategies tailored to the specific context of this chronic condition.