After c6h6o3's first post of inositol, I was curious about how it might affect human glucose metabolism and I also did some web searches. I didn't turn up anything definitive, either.

However, several webpages mentioned inositol's role in the body's calcium storage/release mechanism. WARNING LONG SPECULATON HERE--This made me wonder if inositol could also impact the body's chromium transport system. The reason that I suggest this is because the body's mechanism for moving around and using chromium more closely resembles that of calcium than it does any other metal. The chromium that we eat, which is actually Cr(III), is moved into the cells with chromium transport peptide. (Calcium has its own calcium transport peptide.) Inside the cell walls, Cr(III) binds to the peptide chromodulin (which was, in fact, named after the calcium peptide calmodulin because their mechanisms are so similar). Chromodulin with four chromium ions attached then binds to the beta subunit of the insulin receptor enzyme. This causes the receptor to change its conformation (i.e., shape), which makes it possible for insulin to bind to the alpha subunit of the insulin receptor. This binding "activates" the insulin and it starts metabolizing glucose. This is a rather unique type of "dual-lock and key" mechanism and calcium is the only other common nutrient that is known to be processed by a similar procedure. So, maybe (speculating), inositol affects the chromium/insulin process in a similar matter. If this speculation is true, then inositol's not causing more insulin to be produced but just causing it to be used more effectively.

BTW, one theory on the cause of insulin resistance is that the chromium transport mechanism is breaking down. Perhaps an insulin resistant person doesn't make enough chromodulin and/or enough chromium transport peptide. Most people's standard diet should contain more than enough Cr(III), but the issue may be whether or not it is being utilized adequately. If it isn't, this may in turn be what causes an inadequate utilization of insulin (because without the chromodulin, our insulin just floats around and does nothing!).