Hi Cuba,
Someone posted this a few weeks ago - I found it by typing 'shoulder' in the search bar at the top on the right.
'this is what my consulant told me when he said i had a frozen shoulder.
Muscular and skeletal problems such as yours are virtually universal among people with long-standing, poorly controlled diabetes.
They probably stem from glycosylation of collagen (a protein in tendons).
Collagen fibers normally slide along one another during muscular movement. In glycosylation, they become glued together by glucose. This process can also occur in the skin, which becomes hard and tough (diabetic scleredema).'