I think 20mg is the standard dose, to be taken between 1/2 hour and one hour of your major meal of the day. Because of an extreme problem with acid reflux I took as much as 80mg daily for a short amount of time before surgery, but I took 20mg daily for perhaps twenty years with no known side affects.
I think if I were you, I'd check with your doctor about the symtom of cold hands after eating sugar, and do so at once, it sounds like a diabetic issue. That is a classic symptom of the inability of the body to handle glucose. Glucose issues are very serious, it involves every organ in your body. Keep us informed.
I forget to add that it sounds like hypoglycemia. I'd request a test for that condition.