Back To CoursePathophysiology Textbook
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Jen has taught biology and related fields to students from Kindergarten to University. She has a Master's Degree in Physiology.
You hear a lot about diabetes in the news, especially how it's linked to factors like unhealthy lifestyle decisions and obesity. But that is not true of every case of diabetes. Diabetes mellitus type 1, more commonly known as type 1 diabetes, is an autoimmune disease of the pancreas that results in a lack of insulin.
Let's break that down. An autoimmune disease is caused by the response of an overactive immune system. Just like an overactive imagination can see a shadow and think it's the boogeyman, an overactive immune system can mistake a part of its own body for a pathogen and attack it. In the case of type 1 diabetes, the immune system attacks beta cells, which are cells in the pancreas located in the islets of Langerhans.
Beta cells are important because they produce insulin, the protein hormone required to get glucose, or sugar, into your body's cells. A reduced number of beta cells equals a reduced amount of insulin. When your body is insulin-deficient, you begin to experience the symptoms of type 1 diabetes.
Scientists have isolated several possibilities as to why this autoimmune response takes place, including:
...but there are no definite answers.
Loss of one of the hormones responsible for regulating glucose levels in the body has a profound effect. Let's take a look at some of the symptoms of type 1 diabetes and why they occur.
Don't be intimidated by the new words in this lesson - they share a lot of common roots. Learn the roots, and you will be able to learn the new words without memorizing them. As an example, poly means many or much. You'll notice that root in a few of the terms we'll be using. Other examples are glu or gly for glucose and uri for urine.
Hyperglycemia, or high concentration of glucose in the blood, is the most well-known symptom of diabetes. Since insulin's job is to help glucose get into cells from the bloodstream, it makes sense that a lack of insulin means that a lot of glucose is going to stay in the bloodstream. Normal fasting glucose is about 100 mg/dL. An elevated value of over 125 mg/dL indicates hyperglycemia.
Polyphagia (literally 'very much eating'), or increased hunger, when coupled with weight loss, is another common symptom of type 1 diabetes. If glucose is unable to get into cells, it can't be metabolized to create the energy necessary for cells to function. In a way, the body's cells are starving to death in a sea of glucose. Since the body senses that energy is low, it triggers the hunger response, causing cravings for food, especially sugary carbohydrates.
The presence of glucose in urine, or glycosuria, is not normal. During the process of filtration in a healthy body, the kidneys are able to reabsorb all of the glucose that passes through them. However, if blood glucose levels are over about 170 mg/dL, the kidneys' reabsorption mechanism becomes overwhelmed by the amount of glucose, and some passes into the urine. Glycosuria is often detected by a qualitative commercial dipstick test, where a change in color indicates how much glucose is present.
Polyuria and polydipsia are the increased need to urinate and increased need to drink, respectively. High concentrations of the solute glucose in a diabetic's urine cause water to leave blood plasma and enter the urine through osmosis. This leads to polyuria (literally 'much urine') and results in a frequent need to urinate. In order to make up for this loss of water from the blood, the body's thirst response is triggered, causing polydipsia, the need to drink frequently.
It's vital to note that no one standalone symptom or value can lead to a definitive diagnosis of type 1 diabetes. Let's look at the things we just discussed and how they might lead a medical professional to suspect a case of type 1 diabetes.
If these things are all concurrent, a patient should be tested for the presence of autoantibodies, chemical markers that show the immune system has attacked the islet beta cells in order to distinguish between type 1 and type 2 diabetes. Because type 1 diabetes is not caused by unhealthy lifestyle choices and obesity, it is much less common than type 2 diabetes.
There is no cure for type 1 diabetes, but patients can live long and fairly normal lives if they manage it correctly. Patients must monitor their blood glucose using a meter and, based on their blood glucose levels, administer injections of insulin, either through a syringe or pump. They must also carefully monitor their diet and exercise. Beta cell transplants are being researched as an effective cure but are still in the trial stages.
Poorly managed diabetes can be fatal both in the short- and long-term. Too much insulin can lead to a very low blood glucose level, hypoglycemia. Sometimes called insulin shock, the symptoms of hypoglycemia include weakness, sweating, and mental confusion. Hypoglycemia can generally be treated by eating sugary food or drink, or, in some cases, administration of glucagon, the hormone responsible for releasing glucose stored in the cells into the blood.
Chronic hyperglycemia, on the other hand, occurs when patients do not take enough insulin. This can lead to many different conditions, many of which have the root -path, which means disease or suffering. Among these are neuropathy (damage to the nerves), nephropathy (kidney damage, including eventual kidney failure), retinopathy (eye damage) and cataract, foot problems, and poor wound healing.
In some cases, when hyperglycemia is extreme, the body, unable to use glucose, turns to breaking down fat stores, releasing ketone bodies at a high rate into the blood. This condition can be fatal if the blood becomes too acidic. This is called ketoacidosis and is discussed in detail in another lesson.
Let's summarize what we've learned about type 1 diabetes and review some of the terms we've used.
Type 1 diabetes is a disease caused by the body's autoimmune response to beta islet cells of the pancreas. Since these cells produce insulin, the protein hormone necessary for glucose to get into your body's cells, destruction of the beta cells leads to a deficiency in insulin.
When glucose can't enter your body's cells, a condition called hyperglycemia, or elevated blood glucose levels, results. Hyperglycemia leads to three of the main symptoms of type 1 diabetes, all beginning with the prefix poly-, which means many or much. These are polyphagia (much eating), polydipsia (much drinking), and polyuria (much urination).
Type 1 diabetes is not curable and must be treated with insulin, as well as by careful monitoring of blood glucose levels, diet, and exercise.
Diabetes is about balance. Taking too much insulin can cause hypoglycemia, or blood glucose levels that are too low. On the other hand, consistently taking too little insulin leads to chronic hyperglycemia, which in turn can lead to many other pathologies, or diseases, including those to the kidney, eye, and nervous system. In extreme cases, hyperglycemia causes ketoacidosis, a potentially fatal condition in which there is a high concentration of ketone bodies in the blood that leads to a sharp drop in blood pH.
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Back To CoursePathophysiology Textbook
20 chapters | 274 lessons