What blood glucose level indicates hypoglycaemia?

Hypoglycaemia is commonly defined as a blood glucose level that falls below 4.0 mmol/L. In this context, a blood glucose level of 3.5 mmol/L indicates hypoglycaemia because it is below the threshold that is generally accepted by medical standards for determining low blood sugar. This level could lead to various symptoms, including confusion, irritability, weakness, or even loss of consciousness if not addressed promptly.

The other levels listed (3.9 mmol/L, 4.0 mmol/L, and 5.0 mmol/L) either meet or exceed the threshold of hypoglycaemia, thus not qualifying as indicators of this condition. Understanding these values helps in responding appropriately in a clinical setting or emergency situation.