Hypoglycaemia or low blood sugar occurs when a patient with diabetes mellitus suffers an imbalance between carbohydrate/glucose intake and insulin dosage. If there is more insulin than is needed to help metabolise the available carbohydrate, it causes a range of symptoms such as sweating, trembling, pounding heartbeat, anxiety, hunger, nausea, tiredness and headache. If the situation is not quickly remedied by taking oral sugar or, if severe, giving glucose by injection the patient may become confused, drowsy and uncoordinated, finally lapsing into a coma. Hypoglycaemia is infrequent in people whose diabetes is controlled with diet and oral hypoglycaemic agents.