Phoebe, it was good to hear your update; we eagerly await hearing about your blood test results.
I think you have made a good decision to "go paleo" and you are wise to consider any potential risks of that action, but there should be no problem if you are basically in good health. There is ketosis (the body using fat stores, a desirable and completely normal condition) and there is diabetic ketosis, which is NOT desirable; I don't think the latter should be a concern for you.
For a person with extreme sensitivity to carbohydrates, ANY carbs is too much; even whole wheat bread is OUT. NO white flour in any form (this includes white bread). NO fruit juice or even the occasional soda.
To answer your questions – I do not think there is a risk to rapidly eliminating carbs. You have been following a relatively low-GI diet; but even though pasta al dente is low-GI, it still eventually converts to blood sugar (glucose) and stimulates insulin secretion.
Like you, I am basically eating two meals a day (breakfast is only green tea). If you are not "grazing" through the day, your glucose should drop, triggering the liver to surrender glycogen and break down fat. This will raise your fasting glucose again to "the high side of normal where it usually is.…" I'm afraid that beans and certainly puff pastry will have to be avoided for a while; when the insulin level drops consistently to 3 UU/ML or lower, then carbs can be carefully and SLOWLY added back.
Jimmylegs offered good suggestions for energy and maintaining a healthy diet; and as she said, water is very important. Frankly, with no appetite I find intermittent fasting quite feasible. Unfortunately, none of these techniques has lowered my insulin levels; I am hoping for a better outcome for you. Please keep us informed.
… And now after logging off, I found this article so I am logging back on to post this: http://fitness.mercola.com/sites/fitnes ... L_artNew_1
In view of my earlier comments, you may find this interesting.