I agree with @Helmut that the best way to avoid DKA is to keep your glucose in range. I still think there’s a need to be aware of ketone testing.
In the rare time that I need to check ketones, I find it to be critical. Last year, I woke up one morning and felt some mild nausea. I finger-sticked and my blood sugar came up in high at 262 (14.6).
Luckily, I had a blood ketone meter and strips on hand. My ketone level came in at 4.7 mmol/L, with 5.0 mmol/L marking a threshold of concern. My Loop system lost its glucose data stream while I slept and reverted back to programmed pump basal rates. I must have needed a lot more insulin via basal modulation delivery and I wasn’t getting it.
Anyway, by taking timely action with drinking water, administering Afrezza as well as an IM injection, and preemptively changing out the infusion site, I felt like I avoided a trip to the hospital.
I use a Precision Xtra blood meter and strips. This meter doubles as a glucose meter and is built by Abbott. It’s probably at least ten years old and continues to function dependably. I buy the test strips at Amazon. They are individually foil wrapped so they stay fresh.