Ok.. settle in for a bit of science..
Also take a look at wikipedia for this--quite a good source of basic information.
I can well imagine the 'deer in the headlights' feel !!.
Daibetes is certainly a scary diagnosis when you are sat there in docs office.
It's important to realise that there are 2 principal forms of diabetes (mellitus) : type 1 and type 2 and that in type 1 insulin has to be rplaced by injection wheres in type 2 there is plenty of it around--it's just not doing it's job !!
Insulin is a hormone that is secreted by a specialised gland (the pancreas) in response to a raised level of glucose in the body.
Raised glucose levels occue primarily as a result of eating foods that get broken down (in the gut)and absorbed into the bloodstream as glucose.
Glucose itself is basicaly a small sugar molecule which is most commonly derived from carbohydrates which can vary in molecular size from the very small (sugar) through larger molecules (starches) up to the very large cellulose which we can't use but the ruminant animals do.
The 'small' molecule sugars are absorbed very fast, when you see 'glycaemic index' mentioned it largely relates to the speed of absorption and the rate of rise of blood sugar.
As blood sugar rises insuiln is secreted in the pancreas and moves into circulation, then at cellular level is acts as a 'signal' on the cell mambrane at a 'receptor' which then allows the cell to take up glucose.
Cells (muscle) can only take up a given amount of glucose, once at maximum the excess has to go somewhere as it is actually toxic !!, spare glucose is usually taken up in the liver as first glycogen (useful secondary sugar store) and then as fat in the liver and in fat cells.
The strangeness in the system is thet the cells sensitivity to insuiln varies --the principal problem of type 2 diabetes is that there is plenty of sugar (glucose) plenty of insulin--but mr cell is saying no !!
What research and your example has shown is that hard exercise can and does hugely increase insuiln sensitivity.
The whole 'other' side to insuiln is that it i also powefully anabolic (enhances muscle size) by also acting as the signal for the cell to take up amnino acids (building blocks of muscle protein).
In fact for us older lifters it is the insuiln response we really use to go anabolic--the trick being to :
1. Create insuiln sensitivity by exercising (lifting) hard.
2. Stimulating the insuiln response with a fast carb 'hit' immediately after exercise + a protein hit so taht muscle cells take up both glucose and amino acids.
Hope this helps--big technical subject.
Couple of things to look at :
1.An article on T Nation by editor/boss man T C Louma recently where T C himself basically describes how the much touted 5-6 small meals bodybuilder style eating had given him chronically elevated blood sugars.
2. Articles on the intermittent fasting strategy (martin burkhams site) about how feeding during a shorter window (and larger meals) coupled with a longer fasted period may be much healthier in terms of blood sugar control.
Sorry--would do links to these but although very physiology savvy i am a total non computer dweeb and have never worked out how to do links.