If your concerned about ketoacidosis, probably not a concern for a T2D. T1D’s on the other hand, who have non-functioning pancreas, produce zero insulin so their ketones can skyrocket with low carb intake. Their bodies already use ketones to some degree. However we are talking a level of ketones magnitudes higher, like 15-20 mg/dl.
As his body adapts metabolizing higher fat and lower carbs (and it will) and the mitochondria regain better/proper function and energy production (ATP) relying on ketones more easily you will find ketones go down below where you see them early own. It’s about your body totally hitting stasis and leveling out. When I started keto and fasted 24-48 hours I would see ketones 3.5+ sometimes. Now when I fast 24-48 hours they rarely get above 1.5 and with low fasting glucose on the 80-90 mg/dl range.
Also another way to prove this is this: at first if you use the pee strips you will get a purple result (higher ketones) and generally after months on keto/intermittent fasting that will become less and less evident, again, as your body reaches stasis. The excreted ketones drop, but your level of ketosis is still very viable. You body is just using ketones more efficiently and excreting less.
Hope that is helpful