I don't recall saying that Diana had Sjogren's but gave her the information she needed to decide what she should do. If you don't have dry mouth, then it's highly unlikely that it's Sjogren's. There is a known reason for the disease.....it's autoimmune and if you go long enough with undiagnosed Celiac, your autoimmune system never calms down and you start to develop other AI problems. The root of all disease is inflammation and that's how the AI system runs out of control, along with certain genetic factors.
I don't know of any imbalances that cause reduced tear production. Some medications cause dry eye but when you are being assessed for Sjogen's, they do not test for other issues as you mentioned. In all the research I have done for it, I never came across any issues that would cause it, other than autoimmune in nature. Sjogren's dry eye is much more severe than run of the mill dryness. You also will have dry mouth, which is just as severe. I knew I had it before I was tested. I just let the doctor do the blood work to humor her. They like to have it on paper. With Sjogren's, you will also have dental problems...major dental problems.
Dental problems, check.