Question: is 3.9 blood sugar too low?
Answer: A blood sugar level of between 3.3 or 3.9 mmol/L (60 to 70 mg/dL) is generally considered the lower limit for blood glucose. However, symptoms of hypoglycemia do not usually manifest until levels have reached a low of between 2.8 to 3.0 mmol/L (50 to 54 mg/dL).