Welcome Ran, and I commend you in caring for your wife.
I am a Type 2 DM for 36 years. There are side effects with all medications, but injected/infused insulin is really hormone replacement. Some will argue with me that it is a drug.
In Type 1 DM the insulin secreting Beta cells of the pancreas are destroyed by the immune system. In T2DM long before diagnosis we would have high levels of insulin if a C-Peptide test were done. The reason for this is our skeletal muscle, liver and fat cells resist the attachment of insulin abnormally. This is the result of more than 70 genetic variants. Probably how insulin resistant one is depends upon which and how many of the variants we inherited. The Beta cells weaken and actually die from over work.
Of the drugs used in T2 therapy, one drug class sufonylureas, of which Glipizide is one, does 2 things - they stimulate the Beta cells to secrete more insulin and they increase cellular insulin sensitivity a bit. In my opinion these drugs should only be used in the early stages after diagnosis to gain better blood glucose management. BUT, they should not be used long term because they will accelerate the progression of Beta cell death.
The SGLT2 inhibitors work by lowering the kidneys’ glucose threshold causing glucose to be excreted in the urine. A positive side effect of these drugs is kidney and cardiac protection. A negative side effect is increased possibilities of urinary tract infections. Bacteria loves glucose. It also must be suspended before general anesthesia as it can cause keto acidosis with normal blood glucose.
The side effect of injected insulin of most concern is hypoglycemia (low blood glucose levels). Also because the insulin is not exactly like natural insulin. It has been modified to last longer, either 24 hours plus (long insulin) or up to 5 hours (rapid insulin). Some people find better results with one type insulin over another, and some react to one and not another.
Those with T1 or like me with T2 will use both long (basal) and rapid (bolus) insulin if doing multiple daily injections, or if on a pump using only rapid, which is metered at a constant tiny amount to cover basic needs.
I am not a medical professional of any kind. I am very concerned because in your short post it is evident that your wife has quite advanced T2 for major diabetic complications, poor healing in the extremities, perhaps with peripheral neuropathy, TIAs which indicate vascular damage and kidney disease. While anyone can get any of these, it is those with diabetes that they are most common.
I am stepping over a line here - you might suggest to her doctor that she be started on a SGLT2 inhibitor and at least a long once per day insulin such as Lantus, Toujeo or Levemir. If on the SGLT2 inhibitors she should be encouraged to drink water. In my opinion everyone using any insulin should have a continuous glucose monitor.
If she is not making enough of her own insulin to managed blood glucose levels insulin injections are the only real solution. There is no substitute for insulin. It is a hormone that every vertebrate animal must have to live.
The one other thing is that we T2s need to really restrict the carbs we eat and drink, that’s sugars and starches. The other key thing to increase insulin sensitive is regular exercise. I am not suggesting that considering the history you listed.