Type 2 diabetes at what level of blood glucose should testing for ketones be done

odds are you won't have ketones because you will have insulin even when very high, but urine test ketostrips are cheap insurance
how high is your BG?

If you are feeling unwell and BG is above 14 you could consider doing a test but as Jack says it is most unlikely in a T2.

If it does happen it will be because your pancreas has given up and you are a late late stage T2 moving on to insulin. Much better to make sure that never happens by looking after your diet now and keeping your BG in a good range.

my readings are still highish and was told not to check for ketones