Data sources PubMed, EMBASE and China National Knowledge Infrastructure. Manual review of reference list of included studies.Study selection Cross-sectional studies or the first evaluation of longitudinal studies that were conducted on patients (<18 years old) with a known diagnosis of type 1 diabetes mellitus (DM). The primary outcome was prevalence of dental caries.Data extraction and synthesis Selection of studies, data extraction and risk of bias assessment was performed, independently, by two members of the review team. Inter-rater reliability (kappa = 0.68) was provided. Disagreements were resolved by consensus. The modified Newcastle-Ottawa scale, modified specifically to this review, was used to assess study quality and bias. Where appropriate, data was pooled and analysed using a random-effects model. Subgroup analyses were carried out where possible.Results Four hundred and eighty-eight potential articles were screened; 83 full-text articles were reviewed, with ten (involving a total of 538 patients) included in the meta-analysis. Seven studies were adjudged to be of high quality and three of low quality using the modified Newcastle-Ottawa scale. Overall, pooled prevalence of dental caries, among children and adolescents with type 1 DM, was 67% (95%CI: 0.56-0.77%; I2 = 83%; p<0.01). Subgroup analyses (geographic location and diabetic control) highlighted pooled prevalence was highest at 84% (95%CI: 0.67-0.94%; I2 = 49%; p = 0.16) in South America and 66% (95%CI: 0.43-0.83%; I2 = 87%; p<0.01) in those with bad diabetic control.Conclusions Caries prevalence is high among children and adolescents with type 1 DM. Diabetic children and adolescents need to be regularly screened for dental disease. Consistent preventive measures are required, from all healthcare professionals involved in the care of these patients, to ensure a balance in struck between optimum oral health and diabetic control for these patients.