They could never get her blood sugar down at the nursing home. They have been trying for months and just recently it was found she had a raging urinary tract infection that caused her to go into septic shock. Can sepsis cause that? Could the UTI have been the problem with the sugar the whole time?
Do you know what your mom's A1C is? That will provide some information as to what her averages are. Until she gets under some control, a daily log of her BS levels would be helpful. A doctor can order the facility to check her each day.
I would recommend seeing an Endocrinologist. They are better at diagnosing and treating diabetes IMO. Most primary care doctors aren't that up on it. If there are problems see an Endo.
If she is taking pills and they aren't helping, it could be she needs an adjustment, such as more of the pills or she may need insulin in addition to the pills. ALSO, you can get Type I diabetes at any time in your life. It's not common, but some people get Type I late in life. If that happens, pills don't help. You need insulin only. An Endocrinologist can best make that determination.
I would discuss the matter of diet with the nutritionist at your mom's facility. There are many diabetics in those places and they should have a proper diet for her.
I would also check your mom for yeast infections. They can be very stubborn in people with high blood sugars. They are very uncomfortable and your mom may not be able to communicate that to you.
High blood sugars can cause so many complications. Her health will be at risk until they come down.
Does she take medication for high cholesterol? That type of medication can cause high blood sugars. So do steroids.
Good luck. You are doing the right thing by making this a priority.
Medicare should cover her supplies such as kit, test stripes, etc. with a prescription from a doctor.