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.
Simply so, at what blood sugar level does damage occur?
First, the numbers. “Post-meal blood sugars of 140 mg/dl [milligrams per deciliter] and higher, and fasting blood sugars over 100 mg/dl [can] cause permanent organ damage and cause diabetes to progress,” Ruhl writes.
Secondly, what if my blood sugar is 40?
If hypoglycemia becomes severe, you may not be able to safely swallow food or drink. By this point, your blood glucose level is less than 54 mg/dL—often below 40 mg/dL. You may feel very confused, pass out, or have a seizure. Without prompt treatment, severe hypoglycemia may lead to a coma or even death.