Background: Sarcopenia shares risk factors with various other age-related diseases. This meta-analysis aimed to determine the prevalence of sarcopenia as a comorbid disease. Methods: Medline, EMBASE and Cochrane databases were searched for articles from inception to 8th June 2018, reporting the prevalence of sarcopenia in individuals with a diagnosis of cardiovascular disease (CVD), dementia, diabetes mellitus or respiratory disease and, if applicable their controls. No exclusion criteria were applied with regards to definition of sarcopenia, individuals' age, study design and setting. Meta-analyses were stratified by disease, definition of sarcopenia and continent. Results: The 63 included articles described 17,206 diseased individuals (mean age: 65.3 ± 1.6 years, 49.9% females) and 22,375 non-diseased controls (mean age: 54.6 ± 16.2 years, 53.8% females). The prevalence of sarcopenia in individuals with CVD was 31.4% (95% CI: 22.4–42.1%), no controls were available. The prevalence of sarcopenia was 26.4% (95% CI: 13.6–44.8%) in individuals with dementia compared to 8.3% (95% CI: 2.8–21.9%) in their controls; 31.1% (95% CI: 19.8–45.2%) in individuals with diabetes mellitus compared to 16.2% (95% CI: 9.5–26.2%) in controls; and 26.8% (95% CI: 17.8–38.1%) in individuals with respiratory diseases compared to 13.3% (95% CI: 8.3–20.7%) in controls. Conclusions: Sarcopenia is highly prevalent in individuals with CVD, dementia, diabetes mellitus and respiratory disease.