- Now Diabetes Mellitus is a group of disorders
that's caused by improper function of insulin
which is a hormone responsible for regulating blood sugar
or blood glucose.
And this results in Hyperglycemia.
But since Diabetes is a group of disorders
there's many different
underlying pathophysiological mechanisms
that can cause the disease.
And depending on which mechanism is occurring in someone
the presentation of the disease
can actually be very different.
So before we get started,
I want to briefly talk about the Pancreas.
Now you can see here we have the esophagus coming down
and it dives behind the liver here.
And then it goes into the stomach
and then the stomach goes back behind the liver
and comes out as the small intestine.
And in yellow here, nestled in next to the small intestine
and behind the stomach is the Pancreas.
Now, the Pancreas is frequently referred to
as being comma shaped and you can kind of get that.
Oh, if you kind of turned it on its side
it might look like a comma.
But the way I like to remember how the Pancreas looks is
by thinking about my favorite professional football team
which is the Minnesota Vikings.
And I kind of think the Pancreas
maybe it looks like the horns on the side
of the Minnesota Vikings helmet.
So whatever helps you remember what the Pancreas looks like.
But regardless, the Pancreas has two main functions.
And the first function is Exocrine.
What this means is that the Pancreas secretes Enzymes
into the digestive tract which then chemically digests food
and help your body absorb the nutrients we eat.
So it helps with digestion.
But the Pancreas also has some Endocrine function.
And what this means is that it produces Hormones.
And specifically for the Pancreas
these Hormones help the body with Metabolism.
But what does all this have to do with Diabetes?
Well, I mentioned earlier that Diabetes Mellitus
is caused by dysfunction of insulin
which is one of these Hormones that the Pancreas produces.
And in Type 1 Diabetes,
certain areas of the Endocrine portion of the Pancreas
are destroyed so that the Pancreas cannot produce insulin.
And Type 1 Diabetes
is actually a relatively uncommon disease.
It affects about three out of every 1,000 people
in the United States.
Now, let's dive a little bit closer into the Pancreas
to get a better understanding of what's going on.
So the cells that are responsible for the Endocrine function
of the Pancreas are located in regions of the Pancreas
that are known as the Islets of Langerhans.
So let's just draw those in here.
So in these Islets of Langerhans
there are two main cell types types that are responsible
for producing Hormones.
So in blue here, we have the Alpha cells.
And the Alpha cells are responsible for secreting glucagon.
Then in green we have the Beta cells.
And they're responsible for secreting insulin.
And as I've mentioned before,
these two Hormones are responsible for regulating
much of the bodies metabolism.
And one specific component of this is our Blood glucose
or our Blood sugar level.
So what happens is if someone,
just say, you pretend you just had a meal
and your body starts absorbing the sugar from that meal.
What's going to happen is your Blood sugar levels
or your Blood glucose levels are going to increase.
And this increase in Blood sugar
is sensed by the Beta cells in the Pancreas
and they'll secrete insulin into the blood.
And what it does is that insulin is then going to lower
the Blood glucose level
by causing the cells all over the body to take up
and absorb the glucose
so that they can then use it for energy.
Or it could be stored in the liver.
And either way, the glucose comes out of blood
so the Blood sugar level lowers.
Now if insulin where to act on its own,
the Blood sugar level or Blood glucose level
would get too low.
It would start to decrease from its normal level.
And luckily the Pancreas senses this too in the Alpha cells
or the blue cells here and secretes glucagon.
And what happens then is glucagon
causes the Blood glucose level to raise,
going back to normal.
And it does this by causing the liver
to release the glucose that's stored there.
So what does this all have to do with Diabetes
or specifically Type 1 Diabetes?
Well, in Type 1 Diabetes there is destruction
of these Beta cells in the Pancreas
so the body can't produce the insulin.
And if the body can't produce insulin
it's not able to lower its Blood glucose level
and you have an unbalanced glucagon response.
Which results in this raising of the Blood sugar
and this is known as Hyperglycemia.
Hyper for high, glycemia for blood sugar.
But what is the underlying cause of this destruction
of the Beta cells?
I'm going to just slide this over
so we can get a little more room to work on it.
Well, Type 1 Diabetes is an Autoimmune disease.
And as you can imagine by the name
it has something to do with the immune system.
And what happens is that someone
who develops Type 1 Diabetes was born
with a genetic predisposition to the disease.
Now, this doesn't necessarily mean
that he or she had the disease at birth.
But they just had something in their genes
causing them to be more likely to develop Type 1 Diabetes.
Then over time there was some sort of Environmental trigger.
And this part of the disease process
isn't quite as well understood.
And it could be something potentially like a virus,
or some sort of toxin, or something else.
But regardless, there's some sort of trigger
that causes someone with a genetic predisposition
to have this Autoimmune response
or production of antibodies and T cells
that then attack the Beta cells.
And this is what causes the destruction of the Beta cells
in the absence of the production of insulin.
Which is the underlying cause of Type 1 Diabetes.
And it's this Autoimmune attack of the Beta cells here
that causes the Pancreas
to not be able to produce any insulin.
And when it can't produce any insulin
what happens is that the individual
will develop Type 1 Diabetes.
Well, let me just move over again
so we can get a little more space
to go through why symptoms develop in Type 1 Diabetes.
All right, so imagine a blood vessel here.
And this blood vessel is transporting glucose.
And in a normal individual without Diabetes
this glucose is going to go
to lots of different organs in the body.
Such as the brain, and the muscles, and maybe
give them a little Popeye tattoo for good measure.
As well as the liver, where that glucose can be stored.
But unfortunately in Type 1 Diabetes
the insulin isn't present to take the glucose
out of the blood and help it get to these organs.
It gets blocked, almost like the body is starving
despite having all of this glucose.
And so what happens
is that the liver acts like it is starving
and it releases its stored glucose back into the blood.
And then just like the glucose can't get out of the blood
to some of these organs,
it also can't get out and be stored in the fat
or the adipose tissue, which I'll draw here.
And so what the fat does
is to also kind of try and help the body create more energy
is it breaks down into something known as free fatty acids.
Which I'll just abbreviate FFA,
which the body can then also use for energy.
It's this process here that results in the symptoms
of Type 1 Diabetes.
And the first one is what I'll call
"Starvation in the face of Plenty."
And by this I mean, the body almost acts like it's starving
even though it has all of this glucose present in the blood.
And this results in symptoms like lethargy and fatigue.
Because it's trying to maintain
the little glucose it thinks it has for the brain
and the other organs that are vital and really need it.
So someone with Diabetes will be lethargic and fatigued.
And then the next thing that happens is,
occurs in the kidneys.
Now normally the kidneys reabsorb all of the glucose
that's in the blood and put it back in the blood when it's,
when they're filtering the blood.
But when this glucose level gets so high from Diabetes
it overwhelms the kidneys.
And that glucose spills out in the urine.
And this is known as glucosuria or glucose in the urine.
And glucose is an osmotically active soluble.
What does that mean?
Well, what it means is that it tends to draw water with it.
So as the body pees out all of this glucose
a lot of water comes with it.
And this is known as polyuria
or poly for kind of lots or many and uria for urine.
And this results in dehydration
because you're losing all the water and thirst.
So, someone with Type 1 Diabetes
is frequently going to present
with being tired and fatigued,
going to the bathroom a lot and dehydrated.
And unfortunately, for some individuals,
if they get sick when they have Type 1 Diabetes
before it's been diagnosed,
the body can't compensate for the stress
and you can get a life threatening disease
that's called Diabetic ketoacidosis or DKA
which is a life threatening form
of dehydration and acidosis.
When it comes to diagnosis about 70% of individuals
with Type 1 Diabetes will be diagnosed in this stage
before it gets too bad.
Bit unfortunately, about 30% of individuals
who are diagnosed with Type 1 Diabetes
actually have Diabetic ketoacidosis or DKA,
as their presenting symptom.
So this is just a brief overview of Type 1 Diabetes
which is an Autoimmune disease.
Meaning that there's antibodies and T cells
that destroy the Beta cells of the Pancreas
so that the Pancreas can't produce insulin,
resulting in Hyperglycemia or high blood sugar.
And it's this high blood sugar
that results in all of the symptoms of Type 1 Diabetes.