Objectives: The aim of this study was to assess subclinical changes in right ventricular volumes and function in subjects with prediabetes and diabetes and controls without a history of cardiovascular disease. Methods: Data from 400 participants in the KORA FF4 study without self-reported cardiovascular disease who underwent 3-T whole-body MRI were obtained. The right ventricle was evaluated using the short axis and a four-chamber view. Diabetes was defined according to WHO criteria. Associations between glucose tolerance and right ventricular parameters were assessed using multivariable adjusted linear regression models. Results: Data from 337 participants were available for analysis. Of these, 43 (13%) had diabetes, 87 (26%) had prediabetes, and 207 (61%) were normoglycaemic controls. There was a stepwise decrease in right ventricular volumes in men with prediabetes and diabetes in comparison with controls, including right ventricular end-diastolic volume (β = −20.4 and β = −25.6, respectively; p ≤ 0.005), right ventricular end-systolic volume (β = −12.3 and β = −12.7, respectively; p ≤ 0.037) and right ventricular stroke volume (β = −8.1 and β = −13.1, respectively, p ≤ 0.016). We did not observe any association between prediabetes or diabetes and right ventricular volumes in women or between prediabetes or diabetes and right ventricular ejection fraction in men and women. Conclusions: This study points towards early subclinical changes in right ventricular volumes in men with diabetes and prediabetes. Key Points: • MRI was used to detect subclinical changes in right ventricular parameters.• Diabetes mellitus is associated with right ventricular dysfunction.• Impairment of right ventricular volumes seems to occur predominantly in men.