- Diabetes Mellitus is a group of disorders
that's caused by improper function of insulin,
which is a hormone produced by the pancreas.
And insulin is responsible for helping regulate
blood sugar, or glucose levels, in the blood.
Now since it's a group of diseases,
there are actually multiple different underlying causes
of diabetes mellitus.
And one of these causes is known as Type 2 Diabetes.
Now, before we dive into the actual cause
of Type 2 Diabetes, let's first get a better understanding
of how exactly insulin works.
And there are two major steps.
So, imagine that you just ate a big meal.
Maybe like a bowl of pasta or something.
And your body is currently absorbing all of those nutrients
from your digestive system into your bloodstream.
Now one of these nutrients is glucose,
and as your body absorbs it, that glucose
starts building up in the blood stream.
And in this feeding or absorptive state,
your body wants to store this glucose in places like
the liver and muscle cells
so that it can be used for energy later
when the body needs it.
But unfortunately, glucose on its own
can't get into these cells.
In a sense, these cells are locked.
But fortunately, the pancreas
is able to help with this problem.
So there are a couple types of cells
in the pancreas that sense blood sugar levels.
And these cells are located in the islets of Langerhans.
And these green cells here in the islets of Langerhans
are meant to represent the Beta cells.
And when the blood glucose increases,
the Beta cells of the pancreas sense this change,
and they secrete a hormone known as insulin
into the blood.
And what insulin does is it acts like a key
that can unlock these cells so that the glucose
can be stored in both the liver and the muscle cells.
So you can see that there are two steps
in order for insulin to function properly.
And the first is that these Beta cells
of the endocrine portion of the pancreas
have to be functioning in order to
secrete the insulin into the blood.
And then second, these cells have to respond to the insulin
in order to unlock them so that the glucose can be
taken out of the blood to decrease the blood glucose levels.
Now, diabetes mellitus can be caused
by dysfunction at either of these two steps.
So if the Beta cells aren't functioning properly
or they're being destroyed, such as in Type 1 Diabetes,
there isn't enough insulin to be produced
to unlock the cells.
And what happens is that the glucose
builds up in the bloodstream,
and that person will develop diabetes mellitus.
However, similarly in step two,
if the cells aren't properly responding
to the insulin in the blood, then they can't be unlocked.
And the glucose will build up in the blood vessels
and you'll get hyperglycemia,
and the person will develop diabetes mellitus.
So this is what I meant earlier when I said
that diabetes is a group of disorders,
because multiple different mechanisms
can result in diabetes mellitus.
So, in general, Type 2 Diabetes is caused
by dysfunction of this second step.
And this is known as insulin resistance.
So, in Type 2 Diabetes, the Beta cells of the pancreas
are functioning properly, and they're able
to produce insulin, but that insulin isn't able
to have its proper effect on the cells throughout the body.
However, it is important to note
that as the disease does progress,
the pancreas can become effective
and eventually decrease its insulin production.
But in general, Type 2 Diabetes
is thought of as primarily due to this insulin resistance.
So what exactly causes the cells
to become resistant to insulin?
Well, unfortunately there's no simple answer to this,
and the cause of Type 2 Diabetes is very complex
and includes many different factors
that work together to cause the problem.
So let's get a little bit better idea of this.
I'm gonna just erase some of our work here,
so we can get a little more room.
So what are some of these risk factors?
Well one of the most important ones
is actually genetics.
In fact, having a family history,
say in someone's parents or grandparents,
of Type 2 Diabetes is one of the biggest risk factors
for developing Type 2 Diabetes.
Other factors include obesity,
hypertension, and increasing age.
And it's the interaction of all these different factors
plus more that end up resulting in insulin resistance.
But how can we maybe understand this a little bit better?
Well, one of the factors that we understand
maybe a little bit better than some of the others
is the effect of obesity.
So let's bring back that lock I described earlier.
So if you think of obesity as kind of
this perpetual feeding state, or in a sense,
that the body is continuously being exposed
to insulin released by the pancreas
in an effort to bring down the increased glucose
from this perpetual feeding state.
Over time, the receptors on the cells, or these locks,
become desensitized to the insulin.
And they become resistant to its effect.
So let's use an analogy to help understand
this idea of resistance.
So instead of a lock, pretend this is a person.
And this person decides to put on a baseball cap.
So when you first put on a baseball cap,
you can feel it on your head,
however, over time, say 10, 15 minutes,
this constant stimulation of the touch receptors
results in a desensitization to the feeling of the ball cap
on your head, and it feels like it's no longer there.
So this is kind of similar to the cells in the body.
If they're constantly exposed to this insulin,
they'll stop responding to it,
and the cell won't become unlocked.
Now initially the pancreas is able
to compensate for this resistance by producing more insulin.
However, eventually as time progresses,
the pancreas cannot keep up
to overcome the insulin resistance,
and eventually the body will lose its ability
to lower the blood glucose level with insulin.
And this will result in hyperglycemia
and the complications that are associated with it.
But this process can take time.
In fact, from the time this insulin resistance starts
to when someone would develop symptoms of Type 2 Diabetes
can actually take multiple years.
But at the same time, early diagnosis and treatment
is critical to prevent the serious complications
associated with diabetes.
And for this reason, it's very important
to screen people who are at risk,
people who have some of these risk factors.
It's important to screen them for Type 2 Diabetes,
so they should regularly have their blood glucose levels
monitored for hyperglycemia,
so that it can be detected and treatment can be started
even before he or she will develop symptoms.
So I hope this gives you a better understanding
of what causes Type 2 Diabetes.
It's not caused by a problem with the pancreas itself
and the ability to produce insulin.
Instead, it's caused by this insulin resistance,
by the cells throughout the body
that are supposed to respond to insulin.