Objective To conduct a meta‐analysis investigating the prevalence of type two diabetes mellitus (T2DM) in people with schizophrenia compared to controls. Method Systematic review of electronic databases from inception till November 2014. Articles reporting the prevalence of T2DM in people with schizophrenia and healthy controls (without mental illness) were included. Two independent authors conducted searches and extracted data. A random effects relative risks (RR) meta‐analysis was conducted. Results Twenty‐five studies including 145 718 individuals with schizophrenia (22.5–54.4 years) and 4 343 407 controls were included. The prevalence of T2DM in people with schizophrenia was 9.5% (95% CI = 7.0–12.8, n = 145 718) and 10.75% (95% CI 7.44–14.5%, n = 2698) in studies capturing T2DM according to recognized criteria. The pooled RR across all studies was 1.82 (95% CI = 1.56–2.13; = 4 489 125). Subgroup analyses found a RR of 2.53 (95% CI = 1.68–3.799, n = 17 727) in studies ascertaining T2DM according to recognized criteria and RR 1.65 (95% CI = 1.34–2.03, n = 4 243 389) in studies relying on T2DM determined through medical records. Conclusion People with schizophrenia are at least double the risk of developing T2DM according to recognized T2DM criteria. Proactive lifestyle and screening programmes should be given clinical priority.