ACEIs/ARBs raise K since they antagonize aldosterone (which normally gets rid of K in the collecting duct). CKD itself will cause K retention (due to reduced GFR). This becomes tricky, since you need the ACEIs to slow down further deterioration of renal function, so her electrolytes absolutely need to be watched closely.@Cerberus
I am sorry to hear about your mother.
Diabetes and Hypertension both take their toll on the kidney. You should get BUN and Creatinine every month.
ACE inhibitors should be started at the first sign of microscopic protein in the urine and it is Renoprotective that is these medicines protect the kidney from excessive filtration injury.
The only side effect you should be looking at are two.
Sometimes ACE inhibitor can cause cough. Just hope it doesn't happen to your mother inshAllah because ideally she needs ACE inhibitors indefinitely.
Also second is they lower potassium levels. I suggest that you do monthly serum electrolytes as well, since your mother is already avoiding potassium diet. Too low potassium can suddenly stop the heart.
Beyond that, feel free to ask any questions. I am certified by the Medical Council of Canada, and can help you extensively in this regard.
My prayers are with you.
Cough / angioedmea won't really be an issue considering she can simply be switched to an ARB.