Diabetes mellitus is a group of metabolic diseases characterized by elevated blood glucose levels than is typically required. The level of knowledge on Diabetes should be high in all diabetic patients because high knowledge has the requisite power to improve patient self-care management and hence, good glucose outcomes necessary to increase the life span of people with Diabetes. The study assessed the level of knowledge on Diabetes among adult diabetic patients at the Bono Regional Hospital-Sunyani. This cross-sectional study utilized purposive and convenience sampling techniques in selecting 75 diabetic patients for the study at the Diabetes Clinic of the Bono Regional Hospital. The study found that only 40% of respondents had high knowledge following the diabetes knowledge test conducted. In comparison, the majority of the respondents (60%) had low-level knowledge of their condition. The study recommends that healthcare providers should intensify diabetes education across all diabetes centers in the country. Other researchers are also encouraged to conduct similar studies in other health facilities to have a comprehensive picture of diabetes knowledge among people with Diabetes in Ghana.