Purpose To determine the level of knowledge of patients with diabetes and health care professionals who are specialized in diabetes or diabetes care regarding diabetic eye disease, their treatment and prevention.Methods The Eye-Q questionnaire ((c) National Eye Institute) was translated into German and supplemented with questions about optical coherence tomography (OCT) and intravitreal drugs. 810 patients with diabetes, recruited in secondary diabetes care centers, answered the adapted questionnaire within a cross-sectional study (NCT02311504). In addition, 190 diabetes specialists and 90 diabetes advisors answered the same questions while attending the 49th congress of the German Diabetologic Society (DDG).Results The mean score of the persons with diabetes was 4.9 (of 9 possible points for the Eye-Q questionnaire). In contrast, health professionals had a specific advantage in knowledge (all: 6.8, specialist physician: 7.5, specialists for internal medicine: 7.2, primary care physicians: 7.0, diabetes counselors: 5.8, diabetes assistants 5.7). A considerable number of patients (272 of 805) did still expect early warning signs with the occurrence of any retinopathy. Less obvious effects of diabetes on the eye like dry eye syndrome, cataract and glaucoma were clearly underestimated in the survey among persons affected as well as by caregivers. Questions regarding the use of OCT (38 %) and treatment with intravitreal drugs (16 %) were answered correctly only by a minority of the diabetes specialists.Conclusions Health care professionals were found to have a superior knowledge in contrast to the persons affected. However, some complications in the diabetic eye are not so well known. Relevant gaps in knowledge exist about modern diagnostic and therapeutic modalities. The quite sobering results should encourage better interdisciplinary exchange and education programs.