Background: Ongoing diabetic patient self-management education and support are critical to preventing acute complications and reducing the risk of long-term complications. Their knowledge about these complications could affect their practice toward disease control. Objectives: To assess the level of knowledge about DM complications and identify its determinants among T2DM patients attending Hera diabetic center, September 2019. Subjects and methods: A cross sectional analytic study was conducted at Hera Diabetic Center, MakkahAl-Mukarramah, Saudi Arabia among a sample of type 2 diabetic patients. A self- administered validated questionnaire was used in data collection. It compsed of 3 parts: socio-demographic data, personal history of Diabetes and knowledge About DM complications. Results: Two hundrend and seventy three patients were included in the present study. Their age ranged from 30 to 83 years (mean±standard deviation of 53.6±11 years). More than half of them were males (52.6%). More than half of the participated type 2 diabetic patients (52.7%) had adequate knowledge while 38.5% had inadequate knowledge regarding diabetic complications. Factors significantly associated with patients` knowledge of diabetic complications were marital status (p<0.001), educational level (p=0.029), income (p=0.026), history of referral for funduc examination (0.033) and checking foot anuualy (p=0.029) by physicians, history of diabetic complications among first degree relatives (p=0.001), glycemic control (p=0.011), avoid unhealthy foot/drinks (p=0.005), practicing physical exercise (p=0.005), history of diabetic foot ulcer (p=0.005), and renal problems (p=0.024). Concludion: Knowledge of type 2 diabetic patients regarding diabetic complications is overall acceptable. However, knowledge regarding some important diabetic complications is deficient. Health education for patients and the whole community is urgently needed.