High blood sugar, or hyperglycemia, can lead to a range of health issues, most notably diabetes. Prolonged elevated blood sugar can damage blood vessels, nerves, and organs, increasing the risk of heart disease, kidney damage, and eye complications. Additionally, individuals might experience symptoms such as increased thirst, frequent urination, and fatigue. High blood sugar can also impair cognitive function and contribute to feelings of irritability or anxiety. Maintaining healthy blood sugar levels through diet, exercise, and medication is crucial for preventing these potentially severe health ramifications.