Main complaint you are having is itching... generalised pruritus
Remember, there are many causes.
you do not have rash
It means that the cause is some internal.
As you said, you are having alcohol addiction, pre diabetic stage,some kedne or ureteric problems.. it may be stone or infection.
All the the things can cause generaliged pruritus.
Now, what you have to do? hear..
You just go to dermatologist
Have the investigations to find out all the diseases you have.
and then after you take treatment.
But, my humble request, for god sake you stop alcohol.. you may have good health and there would be prevention of many diseases.
Antihistaminics woukd be helpful to prevent itching.
I hope you got myanswer.
Dr. Ilyas Patel MD