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  • - 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.

- Diabetes Mellitus is a group of disorders

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B2 中高級 美國腔

病理生理學 - II型糖尿病|內分泌系統疾病|NCLEX-RN|可汗學院 (Pathophysiology - Type II diabetes | Endocrine system diseases | NCLEX-RN | Khan Academy)

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    Hope Bai 發佈於 2021 年 01 月 14 日
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