Background: This meta-analysis aims to: (i) describe the pooled prevalence of diabetes in people with intellectual disabilities, (ii) investigate the association with demographic, clinical and treatment-related factors and (iii) compare the prevalence versus age- and gender-matched general population controls. Methods: PubMed, Embase and CINAHL were searched until 01 May 2021. Random effects meta-analysis and an odds ratio analysis were conducted to compare rates with controls. Results: The trim- and fill-adjusted pooled diabetes prevalence amongst 55,548 individuals with intellectual disabilities (N studies = 33) was 8.5% (95% CI = 7.2%-10.0%). The trim- and fill-adjusted odds for diabetes was 2.46 times higher (95% CI = 1.89-3.21) (n = 42,684) versus controls (n = 4,177,550). Older age (R[superscript 2] = 0.83, p < 0.001), smoking (R[superscript 2] = 0.30, p = 0.009) and co-morbid depression (R[superscript 2] = 0.18, p = 0.04), anxiety (R[superscript 2] = 0.97, p < 0.001), and hypertension (R[superscript 2] = 0.29, p < 0.001) were associated with higher diabetes prevalence rates. Conclusions: Our findings demonstrate that people with intellectual disabilities are at an increased risk of diabetes, and therefore routine screening and multidisciplinary management of diabetes is needed.