how do i know if my blood sugar is low

Low blood sugar, also called hypoglycemia, is typically defined as a blood sugar level below 70 mg/dL (3.9 mmol/L). Symptoms to watch for include feeling weak or tired, shaking, sweating, headache, hunger, anxiety or nervousness, irritability, trouble thinking clearly, blurry vision, and a fast or pounding heartbeat. Severe low blood sugar can cause seizures, fainting, or unconsciousness. For people with diabetes, it is best to check blood sugar levels with a glucose meter if symptoms appear, especially if below 4 mmol/L (about 72 mg/dL) as immediate action may be needed. Some individuals may have low blood sugar without obvious symptoms, a condition called hypoglycemic unawareness, where continuous glucose monitoring can help detect and prevent dangerously low levels.