Daisy222
You will only go into ketosis (ie normal fat-burning) if you do not have enough carbohydrate in your diet for your body to use for energy and it turns to using ketones from broken-down fat stores instead.
If you eat a high-carb meal you will no longer be in ketosis, and it might take 3 days for your body to use up all the carbs in that meal and start ketosis again.
My comment in my previous post . . .
your blood sugars do not rise . . . is very misleading, and I am glad you pointed it out. I should have said . . .
when in ketosis your blood sugars do not rise abnormally high . . . and I have edited my original post to make more sense. Your blood sugars will rise as usual in response to what you eat or drink - in your case the cafe latte, where the 8g carb comes from milk sugars and any added sugar. Did you know exactly what went into it? I believe the caffeine may also affect your blood glucose response.
If you eat below 50g of carb per day you are likely to remain in ketosis, which will lead to traces of ketones in your urine. However, we are all different - I don't show ketones at 50g of carb; some people may show them at a higher level. How much carb are you eating when you say ". . . ketones still show up"?
The ketosis itself does not act on your blood glucose levels. Carbohydrate in your diet is converted into glucose by the body, and put into the bloodstream for the insulin to put into the muscle cells (for energy), the liver (for emergency stores) and any spare into the fat cells. Ketosis means there is not enough carbohydrate energy for the body to use; it turns first to the liver, and when those stores have run out, starts using the stored fat by breaking it down for energy which produces ketones. If you are not eating many carbs, your blood sugar doesn't rise very high, and your pancreas doesn't have to produce so much insulin to deal with it.
About 25% of the protein you eat is also converted into glucose, but very slowly, so it doesn't spike your glucose levels as quickly (or as high) as a plate of mashed potato would.
Do you test before and 2 hours after your meals? In your place I would do that for a few days, to see what the difference is between the readings just before and 2 hours after. The later reading should be somewhere near the first. If it's significantly higher, keep a food diary as well and double-check the amount of carbs you're eating. It's easy for a few extra to creep in!
If you are still getting ketones at (say) about 70g of carb daily, and you are still getting post-meal swings of up to 11 at the 2 hour point, or if you ever feel unwell (nausea etc) for no know cause, see your GP.
But above all, don't panic!

Stress can also raise your blood glucose levels. Ketoacidosis is not common in Type 2s. Keep a daily diary of food eaten, carb intake, and BG readings for a week, so you know what's going on and have something to show your GP if necessary.
If you are eating less than 50g carb daily, all the time, you may well be permanently in ketosis.
Please ask again if anything is not clear. Posting an example of your daily food intake might help us to give more advice.
Viv 8)
edited for typos.