Hello,
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Headache with diabetes can be due to various reasons as low sugar levels,high blood pressure,glaucoma(raised intraocular pressure i.e.eye pressure),tension headache,cerebrovascular causes,stress etc.
It requires a proper examination of eyes,blood sugar levels,sinus etc and investigations.Since I am not examining you it is very difficult to comment on net.Kindly visit a Physician soon for proper evaluation.
Take Care!