Question: how low is low blood sugar for a diabetic?
Answer: A blood sugar level below 70 mg/dL (3.9 mmol/L) is low and can harm you. A blood sugar level below 54 mg/dL (3.0 mmol/L) is a cause for immediate action. You are at risk for low blood sugar if you have diabetes and are taking any of the following diabetes medicines: Insulin.