“It’s the key that unlocks the door to let glucose into cells.” -- every endocrinologist to every newly diagnosed person with diabetes ever.
But that’s a way over-simplification. Insulin does so much more! It has roles in the metabolism of glucose, fat, protein, and in other total-body processes like growth, vascular function, and the function of other hormones.
What Doesn't Insulin Do Is The Real Question
Just a few highlights of what else insulin does (and, to be clear, I'm talking about insulin made by the human body):
- Insulin inhibits the breakdown and release of glucose from glycogen in the liver (it’s the anti-glucagon)
- Insulin inhibits use of proteins to be converted into glucose by liver (anti-glucagon)
- Insulin increases storage of glucose as glycogen (glucose molecules bound together in a long chain) in the liver (anti-glucagon)
- Insulin decreases secretion of glucagon from alpha cells
- Insulin increases uptake of triglycerides -- how our body stores fat (through fatty acids and glycerol) -- from blood or muscle to store in fat cells
- Insulin inhibits ketone production (byproduct of fat breakdown, used by the brain for fuel in times of low glucose; our brain can’t store glucose in its cells like our muscles/liver can) by inhibiting fat breakdown and fatty acid uptake in the liver
- Insulin further prevents ketosis/acidosis by promoting excretion of ketone bodies from body (in breath, urine)
- Insulin promotes protein synthesis; inhibits protein breakdown
And those are just the highlights that are directly related to metabolism of glucose, fat, and protein! It gets so much more complicated than that.
Understanding Insulin Means Understanding Our Bodies
Because insulin is so intertwined in so many other aspects of bodily function, when insulin is dysregulated (like in diabetes), all this stuff gets dysregulated.
For those of us on insulin, for example, giving exogenous insulin cannot hold a candle to the real deal! Don’t get me wrong, insulin is a lifesaver and we must have it. But man made insulin only has one job (to regulate the sugar levels in the blood), while the real thing works to stabilize so many other aspects of the human body.
Understanding all of these vital roles insulin plays, though, can help those of us with diabetes to understand what we experience in diabetes and how to manage it. For example, this is why it’s hard for people with diabetes to lose weight, why our liver isn’t always able to put out enough glucose to correct a low, why ketones are not inherently bad, and so many other fascinating health elements that go way beyond diabetes.
Insulin is truly the Renaissance Hormone!