Some of the main causes of headaches for those diagnosed with diabetes are listed below.

Dehydration
Slowly sip 3-5 litres water daily. Replace electrolytes as needed.

Low blood glucose levels, hypoglycemia, numbers approaching 3.9(70) or less.
Bring your blood glucose levels up a bit.

High blood glucose levels, hyperglycemia, numbers above 10.0(180).
Bring your numbers down a bit over time.

There could be other causes that might require medications. So see a doctor.

Good luck.

Greetings I'd like to ask how to treat a diabetic headache at home it's been 3 days now I hardly sleep