Does COPD And Chronic Pneumonia Cause Delirium?

My mother in law has copd, and chronic pneumonia. At least every other month she is hospitalized due to pneumonia. Typically her blood sugar raises above 200 while on the hospital being treated. Recently, we have been able to know she is sick from her lack of cohesiveness when speaking and from her constant babbling of nonsense. What could be causing the disconnect and causing her to lose her mind when she's sick?