@anon84811: I cannot speak for a doctor, of course, but a blood glucose level in the 20s and 30s, by my calculations, runs to levels (as measured in the U.S.) between 350 and 650. These levels are extremely dangerous for any period of time.
Gastroparesis does not make the diabetes worse. Diabetes causes the gastroparesis, and it is a classic complication of long-term, uncontrolled diabetes, or poorly controlled diabetes.
Some reversal may be possible, if your spouse is willing to make the life changes necessary for good health. She's got to get her diet under control, take her prescribed medication and do some exercise, if possible. She must get some control of her glucose levels in order to be healthier.