I was diagnosed with frozen shoulder in 1995 after going through 5 years of pain. Little did I or the doctors know then about this condition. There have been a lot of articles since the mid nineties about frozen shoulder and diabetes.
According to most articles / research the incidence of frozen shoulder in Type 1 diabetics can vary between 15% and 55%. The incidence of frozen shoulder in Type 2 diabetics can be between 25% and 75%.
So if you get pain in your shoulder when you comb your hair, lift something heavy or when you lie down to sleep, this may be the cause. Also if you have stiffness in the shoulder this can also be a sign. Don't just blame it on old age or arthritis.
The important thing is to get it diagnosed early. Frozen shoulder in diabetics, if not treated early, can become resistant to treatment. Anti inflammatory drugs and physio exercises which you can do yourself at home can prevent the condition getting worse and even cure it in most cases.
If you put frozen shoulder and diabetes into your search engine there are plenty of articles to read.