Hi, thanks for using healthcare magic
Extremely high or low blood sugar
can cause seizures.
The seizure that your cousin experienced is likely as a result of his severe hyperglycaemia. The high blood is thought to result in increase excitability of the neurons or nerve
cells in the brain which can then result in a seizure.
Seizures related to high blood sugar would respond best to medication to lower the sugar level and to fluids to rehydrate the body.
I hope this helps