Diabetics rely on injected insulin or tablets to keep their blood sugar at normal levels.
Occasionally they can inject too much insulin or because they don’t eat at the right time the tablets or insulin lower the blood sugar too much, causing loss of consciousness.
The patient may complain of sweating, anxiety and heart palpitations before lapsing into unconsciousness. If they are diabetic they will usually know they are going "hypo" and will take some food.
If they are unconscious the first aider can smear glucose gel onto the gums and must get them to an Emergency Centre as soon as possible. Low blood glucose is life threatening.