Since you have diabetes, you might want to see an endocrinologist. Maybe he or she would see some connection that others have overlooked. Other than that, you might want to try an alternative health care practitioner. Given the complexity of your situation, I'd recommend a naturopath (N.D.) or acupuncturist (L.Ac.). Are you having any other symptoms--even things seemingly not related to your headache or diabetes? Does anything seem to help--or exacerbate--the headache pain? Good luck!