Excessive thirst is a major symptom of high blood sugars. Other major symptoms include dry mouth, increased hunger (especially after eating), frequent urination, fatigue, unexplained weight loss, blurred vision, and headaches. These symptoms are all caused by high blood sugar. Other symptoms of type 2 diabetes may include slow-healing wounds, itching, numbness and tingling of the hands and feet, weight gain, frequent yeast infections, and impotency.