I would not be able to give you any specific advice, since you haven't mentioned the specific nature of her psychiatric disorder.
But, the fact that your mom is 70 years old, and has Diabetes, makes it mandatory for you to get her evaluated with a Physician and a Psychiatrist. Diabetes itself, brings a host of other complications. Old in this age, individiuals are susceptible to a medical condition called 'Delirium' (patients can get confused, disoriented, show personality changes, sleep disturbances, and other behavioral disturbances). The drugs she's on need to be monitored. Also if she's not eating well, you have get her blood tests, like Serum Electrolytes done, apart from her regular blood sugar checks.
Also a Psychiatrist would evaluate her for signs of Dementia, which could well be the reason for the mental disturbances in question here.
So, get her to a good medical faciltiy, where there is a good Psychiatrist and a Physician.