I was waiting for your reply.
There can be different causes for the headache.
But when you are about to black out from it,
I would suggest to get an examination by doctor without delay.
You need to rule out any brain or vascular issues.
CT scan or MR angio can be taken if doctor feels after examination.
Fasting sugar of that level would not cause such headache.
Your blood pressure is running high.
That needs an evaluation too.
I hope this information helps.
I will be happy to assist, if you need any clarification.
Please feel free for any follow up query.