There's another way. If you get a reading like that, go to A & E, and when you see the doctor, tell them your GP won't refer you to the diabetic clinic. The A&E can refer you too, I believe.
Also, see this NHS page about your care. It's practically the first sentence on the page that you will see a specialist:
http://www.nhs.uk/conditions/diabetes-type1/Pages/Treatment.aspx
I think it would be a good idea to print this off and take it to your GP, if that doesn't convince them them tell them you'll write to your local MP.
Good luck
