Diabetic patients can detect the presence of diabetes mellitus by observing whether they have symptoms such as excessive drinking, excessive eating, excessive urination, weight loss, etc., and by monitoring their own blood glucose. 1. Drinking, eating and urinating: Diabetic patients have high sugar content in urine, which will produce osmotic diuresis, thus causing polyuria; diabetic patients with high blood glucose and high blood osmolality will stimulate the thirst center, resulting in polydrinking; as glucose can not be properly utilized, it will cause energy deficiency, and in order to maintain the body’s activities, it will cause polydipsia. 2. Weight loss: Since blood glucose cannot be utilized, it will decompose fats and proteins to supply energy for the body, and the decomposition of fats will lead to weight loss. 3. Self-testing: You can buy a blood glucose meter and measure the peripheral blood to check your blood glucose. However, you need to consult a doctor for a standardized test in order to make a clear diagnosis. If you are suspected of having diabetes, you need to consult a doctor for a clear diagnosis to avoid delaying your condition.