| Em,
I have several articles on my web site, which refer to the research backing up what I posted.
Blue sky,
What you wrote is partially but not entirely true. My endo claims that it is not possible to determine the extent of IR from C-peptide or fasting insulin tests. The very high insulin levels you cite happen early on for some Type 2s, but by the time most show up in a doctor's office they have lost 50-80% of their beta cell mass and hence their insulin production is much lower.
It is possible for many people diagnosed as Type 2s to have widely varying amoutns of insulin sensitivity, because in many ways "Type 2" is a "garbage can" diagnosis. If someone isn't Type 1--i.e. has no autoimmune markeres, they get diagnosed as Type 2. But the diagnosis covers hundreds of different genetic flaws and underlying causes and varying degrees of beta cell dysfunction.
There's a pancreas autopsy study I link to on my site where they found that the rate of beta cell death was much higher in lean Type 2s, for example. And NIH statistics say that about 20% of "Type 2s" are normal weight.
I know quite a few normal weight Type 2s, whose IR varies hugely. Some are eating very low carb and stilll need a lot of insulin to get normal numbers. Some eat can 30-40 grams per meal and get completely normal numbers. I know a couple other officially type 2 people who use insulin doses similar to the tiny ones I use who respond strongly to them. Some people get dramatic blood sugar drops in response to Byetta, others see their bgs go up.
And while there are those who can restore normal numbers by losing a lot of weight as IR seems to be their main problem. they do seem to be in a minority, and probably were in the very early stages of deterioration at diagnosis. Bernstein reports only knowing one, a male. I have encountered a few online, all male.
Because the underlying dysfunctions can be so different, the effective treatments differ too. That's pretty much the message of the book I've just published: that people diagnosed with Type 2 have to carefully observe their blood sugar responses to food and meds to determine what the nature of their individual case might be, and use what they learn to choose the most effective treatments for them, which aren't going to be the same as for someone else diagnosed as Type 2.
With the more drugs coming on line for Type 2, this is becoming much clearer. Only 25% of Type 2s have a strong response to Byetta, and even fewer have a dramatic response, but for those who do, it is a wondeful drug. For others, they might as well be injecting water. But it is possible from past history to get a good idea who might be in the responder column.  | 
