What Could Cold And Headache In Diabetics Suggest?

I have had type 2 diabetes for 10 years.Last Friday I had a couple of drinks (2 pints of cider) and some pizza before going home. When I went to bed I felt cold, very cold, even though my flat was not cold. I put the heating on all night and still found myself shivering uncontrollably for 30 minutes or so. In the morning I had a headache which went away gradually. Any idea what this means?