What level of blood sugar is dangerous?

Blood sugar levels become concerning when they are significantly above or below the healthy range. A fasting blood sugar level of 70–99 mg/dL is generally normal, while 100–125 mg/dL suggests prediabetes, and ≥126 mg/dL may indicate diabetes. For a random (non-fasting) blood sugar reading, a value of ≥200 mg/dL, particularly with diabetes symptoms, may indicate diabetes. A blood sugar level below 70 mg/dL is considered low, while levels around 300 mg/dL or higher can be dangerous and need prompt medical attention. Extremely high or low blood sugar can cause symptoms such as dizziness, confusion, or loss of consciousness if left untreated. If your reading reaches these levels, seek medical advice rather than waiting for it to settle.