To
function properly, cells need a steady fuel
supply. Blood sugar is the key fuel for most
cells in the body, and the body produces the
hormone insulin precisely in order to
help get energy to the cells that need it. Insulin
is like a "key" that turns on the
glucose transport "ignition" (insulin
receptor) which is located on the surface
of the cell (see Figure 3).
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Figure 3: How the cell takes in blood
sugar.
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When the "key" (insulin) activates
the "ignition" (the insulin receptor),
it turns on the engines of the "tanker
trucks" (GLUcose Transporters, or
GLUTs) that do the work of hauling glucose
(blood sugar) out of your bloodstream and into
your cells. So to get your cells the energy
they need - and to keep blood sugar from building
up to dangerously high levels - insulin has
to tell your cells to take up blood
sugar … and the cell also has to listen
to the signal, and mobilize the GLUT transporters.
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Sugar
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The
system is efficient and remarkably adaptable,
but it has its limits. The fact is that there's
only so much blood sugar that your cells can
take in at a time. And as soaring rates of diabetes
show, North Americans have been overtaxing those
limits for generations. Our fast-paced lifestyles
and processed-food diets cause most of us to
take in more Calories - and, especially, more
carbohydrate - than our bodies can handle. After
years of being asked, by insulin, to take in
more glucose than they can use, eventually
your cells stop responding properly to insulin's
signal.
