To quote Peter at hyperlipid, some amount of peripheral insulin resistance is a standard adaptation to LC/VLC. Basically, since your brain needs some glucose, the rest of your body will attempt to spare as much as it can so that your brain can get what it needs. It does so by causing your muscles to become insulin resistant; this reduces their blood sugar uptake, leaving more available for your brain.

If you were to consistently eat some amount of carbs for a week or two, your peripheral insulin sensitivity would improve and the spike/duration of your post-carby meal BG should decrease.

edit: I should note that it's not just your brain which has an absolute requirement for glucose - red blood cells come to mind.

I was absolutely shocked when I got a blood glucose tester and saw how high my BG went after a small carb meal - and how long it stayed elevated. This event btw was the moment that I switched to a low-carb (or even zero carb as much as practical) diet. The Paleo stuff came later.

I'm positive I probably was prediabetic. This means that I was to a degree insulin resistant - and that's a kind of body damage caused by a lifetime of abuse, and is not going to change dramatically for a very long time. As long as I keep my carb intake very low I'm at least not doing further damage to myself.

Even after a few months now of LC/VLC I still feel that blood glucose sleepiness if I eat some carb rich foods. Any fruit would cause a huge spike - and I'm sure lentils are not a good idea for anyone who it insulin resistant (I doubt Tim Ferris is insulin resistant btw).

pfw I'll check out that info ("Peter at hyperlipid...") but I'm dubious it's exactly like that - after a while on low-carbs the body gets efficient at ketosis and can happily produce all the glucose it needs for brain metabolism (Taubes makes this point also). But I'm curious about this and will read up on it. Perhaps that advice is more appropriate for someone not already insulin resistant?

For me (emphasis on me - your mileage may vary) it's like suggesting I 'consistently' hit myself on the head with a hammer - daily, just a little bit - so it'd improve my response if I do it really hard later on.

My current best way to avoid the urge to inhale some kinds of carbs is to eat a couple tablespoons of coconut oil or an egg or two. I want to experiment with other fats for this too. I also still indulge in nuts and cheese once in a while if famished. I can feel the glucose 'spike' (and subsequent sleepiness) but it's MUCH better for me than any fructose or starch containing food.

Now here is what can explain your high blood sugar. But don't worry, they'll go down once you're CNS is fully burned out, your fully insulin resistant, and the only thing getting you out of bed is another cup of coffee. Now, I am not a biology major, and most of this I learned from doctors and high school bio.

WHen humans do not eat carbs, their sympathetic tone increases. This results in a hormonal cascade with characteristics such as increased SHBG, cortisol, and insulin. The body starts looking for readily available glucose to flee from the saber tooth tiger or gather enough energy to go looking for food. Since you have no stored glycogen, the body has no choice but to create glucose from proteins through its gluconeogenic pathway. Unfortunately, now that means the proteins you are eating aren't going helping to build or even preserve muscle tissue, as it is now being catabolized to provide for your glucose needs. This is an unsustainable process, as eventually your CNS will become exhausted or you'll have catabolized all endogenous sources of protein for glucose. Since you insist for one reason or another on not consuming healthy carbohydrates, the body stays in this hyper-stressed state.

If you're not as science-ie as I am, you can think of your body like an economy.

Keynes never believed that the capitalist system was failing in its ability to allocate resources efficiently. Rather, it was in the total volume out output (GDP) in which it was falling short. This what has been interpreted as Keynes' belief that the economy can persist in a position of sub-normal activity, without any tendency towards recovery or further collapse. It is an unemployment equilibrium-disequilibrium. Your body (the economy) is also obviously efficient at allocating resources (calories) too. However, the volume resources being allocated (glucose, in this case) is insufficient, causing it to persist in this hyper-stressed state (reduced output and employment). You can mask the problem and offer a short term pick me up through the use of your sympathetic nervous system (government make-work policies) and gluconeogenic pathways (the central bank) to create glucose (money). However, this will only delay the inevitable and much greater collapse (adrenal burnout?). you could otherwise provide the resource (glucose) that is in demand through a sustainable method in the long run by pealing an orange, picking some berries, and roasting a sweet potato. Now a sustainable source of glucose/money is flowing in at regular intervals, and your body will now return to a state of normal sympathetic tone (output).

You wrote,"The past three years have been stressful enough to generate an increase in weight gain not seen before in my body. I am glad I changed over to a low carb diet before things get worse."

Are you sure it's the external environment that caused the stress and weight gain? It just happened to coincide with the period you decided to go low carb?

For some people it may be due to high amount protein in the diet. See The High Blood Glucose Dilemma on Low Carb (LC) Diets http://paleohacks.com/questions/108225/the-high-blood-glucose-dilemma-on-low-carb-lc-diets#axzz1y3v57ipl

I read, on the Perfect Health Diet blog if I remember right, that BS below 140 is considered relatively non-toxic. So although your seeing 130 for a few hours, the good news is your not seeing severely damaging levels.

As people have pointed out here, low-carb diets cause some insulin resistance /glucose intolerance. I'm of the opinnion that it's eating of lot of fat that causes the problem with carbohydrate metabolism. Though the human research is not quite conclusive, there are plenty of studies showing lower glucose tolerance with hig-fat intake (not necessarily very low carb diets).

I also found this one study that showed how it happens.

Therefore in contrast to the originally postulated mechanism in which free fatty acids were thought to inhibit insulin-stimulated glucose uptake in muscle through initial inhibition of pyruvate dehydrogenase these results demonstrate that free fatty acids induce insulin resistance in humans by initial inhibition of glucose transport/phosphorylation which is then followed by an z 50% reduction in both the rate of muscle glycogen synthesis and glucose oxidation.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC507380/pdf/972859.pdf