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What is diabetes mellitus?

What is Diabetes Mellitus?

Diabetes mellitus is a common disease where there is too much sugar (glucose) floating around in your blood. This occurs because either the pancreas can’t produce enough insulin or the cells in your body have become resistant to insulin.

How does your body normally regulate glucose?

When you eat food, the amount of glucose in your blood skyrockets. That’s because the food you eat is converted into glucose (usable energy for your cells) and enters your blood to be transported to your cells around the body. Special cells in your pancreas sense the increase of glucose and release insulin into your blood. Insulin has a lot of different jobs, but one of its main tasks is to help decrease blood glucose levels. It does this by activating a system which transports glucose from your blood into your cells. It also decreases blood glucose by stimulating an enzyme called glycogen synthase in the liver. This molecule is responsible for making glycogen, a long string of glucose, which is then stored in the liver and used in the future when there is a period of low blood glucose. As insulin works on your body, the amount of glucose in the blood slowly returns to the same level it was before you ate. This glucose level when you haven’t eaten recently (called fasting glucose) sits around 3.5-6 mmol/L (70-110 mg/dL). Just after a meal, your blood glucose can jump as high as 7.8mmol/L (140 mg/dL) depending on how much and what you ate.

What happens in diabetes mellitus?

There are two types of diabetes mellitus, type 1 and type 2. In both types, your body has trouble transporting sugar from your blood into your cells. This leads to high levels of glucose in your blood and a deficiency of glucose in your cells. The main difference between type 1 and type 2 diabetes mellitus is the underlying mechanisms that cause your blood sugar to stray from the normal range.
Type 1 DM:
Type 1 diabetics suffer from a complete lack of insulin in their bodies. Although the exact cause has not been identified, it is clear that the cells which make insulin are destroyed by the body’s own immune system. This occurs due to autoimmunity, a process by which the immune system believes some of the body’s cells are foreign and targets them for destruction. Eventually, the body destroys all of these cells and the symptoms of diabetes manifest.
Type 2 DM:
People with type 2 diabetes can still make insulin, but their cells have some degree of insulin resistance. Type 2 diabetes is a continuum which begins with insulin resistance and can end in loss of insulin secretion. When cells initially become resistant to insulin, the body increases the amount of insulin made to counteract this effect and keep glucose levels in a normal range. In fact, early type 2 diabetics have higher levels of insulin in their body than non-diabetics. Eventually, the body cannot compensate enough, and blood glucose levels begin to rise. The pancreatic cells begin working overtime to produce more and more insulin and eventually burn out. As type 2 diabetes continues to progress, patients have to start taking insulin to ensure they have enough of the molecule in their body.

What are the symptoms of diabetes mellitus?

Initial symptoms:
Type 1: The classic initial presentation of type 1 diabetes is increased thirst, increased urination, weight loss, hunger due to starvation of cells, and fatigue. As blood glucose levels increase, the body tries to remove excess glucose in the urine and dilute the blood by increasing water intake. However, many patients are initially diagnosed when they come to the hospital very sick in a state called diabetic ketoacidosis. This occurs when cells use alternative energy producing mechanisms, leading to high levels of byproducts called ketoacids. Ketoacids acidify the blood, leading to dangerous acid-base disturbances. Diabetic ketoacidosis causes abdominal pain, nausea/vomiting, and drowsiness and is a potentially life-threatening condition.
Type 2: The symptoms of type 2 DM are similar to type 1, but generally occur later in life and have a more gradual onset. 40% of patients have no symptoms. The other 60% can present with increased thirst and urination, diabetic ketoacidosis, or a condition called hyperosmolar hyperglycemic state, a state of severe dehydration requiring hospitalization.

Long-term complications of Diabetes Mellitus:

Many of the major complications of diabetes, including coronary artery disease, cardiovascular disease, peripheral vascular disease, and cerebrovascular disease are caused by damage to large vessels in the body. High glucose levels lead to chronic inflammation in the body, including the walls of the arteries in the blood. This chronic inflammation leads to atherosclerosis, a buildup of a plaque with a fibrous cap on the walls of the arteries. This narrows the arteries and leads to decreased blood flow in the arteries. In addition, these plaques can rupture and lead to the formation of a blood clot which blocks off blood flow. If this happens in the brain or the heart, it causes a stroke or a heart attack.
High blood glucose levels may also damage the smallest vessels in the body, leading to multiple long-term microvascular complications. This damage both destroys the cells in the blood vessels and leads to decreased blood flow and tissue death. Poorly controlled diabetes can cause retinopathy (damage to the retina in the eyes, leading to blindness), nephropathy (damage to the kidneys resulting in kidney failure), neuropathy (damage to your nerves, which can cause numbness or tingling), and gastroparesis (dysfunction of your digestive system causing chronic vomiting and abdominal pain). All of these symptoms are caused by glucose-induced damage to blood vessels.
Diabetes has a large negative effect on the body’s immune system. High glucose levels ramp up the activity of immune cells. These cells eventually become exhausted and desensitized, decreasing their effectiveness against invading pathogens. Poorly controlled diabetics are more prone to severe skin infections and have longer hospital stays for infections like pneumonia or urinary tract infections.

How likely are you to get it?

It’s unclear who gets type 1 diabetes or how to prevent it. Given the main cause of type 1 diabetes is autoimmunity, environmental factors are likely the largest risk factor. Type 2 diabetes, on the other hand, is directly related to obesity and diet. Overweight individuals become more and more resistant to insulin and are much more likely to get diabetes. Physical fitness and a healthy diet are the most important aspects of type 2 diabetes prevention. Both types of diabetes have genetic predispositions, with type 2 having a larger genetic component to the disease.

How do you treat it?

The only effective treatment in type 1 diabetes is administering insulin as these patients no longer produce it. There are many different types of insulin and different regimens but many patients will use a long-acting insulin at night supplemented by a short-acting insulin before meal times. Newer treatment regimens include the use of an insulin pump where blood glucose levels are entered into a machine which then uses an algorithm to pump insulin into the body.
Type 2 diabetics have more options. Initial therapy for type 2 diabetics with mild disease is lifestyle modification: a healthy diet with exercise to help lose weight. If this fails, the first medication used is typically Metformin, a drug which stops the liver from making glucose in a process called gluconeogenesis. It also increases the number of insulin receptors present on cells, so they become more sensitive to insulin. In between Metformin and insulin therapy are a number of drugs which help increase the release of insulin from the pancreas. These include sulfonylureas, a-glucosidase inhibitors, and glinides.

Consider the following:

  • Sometimes, pregnant women can develop diabetes while they are pregnant, a process called gestational diabetes. This usually reverses once they give birth, but can persist after the pregnancy. Gestational diabetes is similar to type 2 diabetes: the hallmark of this disease is insulin resistance. During the second trimester, pregnant women increase their resistance to insulin and have higher blood sugar levels, likely to increase delivery of glucose to the fetus. Most women increase the amount of insulin produced from the pancreas, but women with gestational diabetes cannot produce enough and functionally become type 2 diabetics throughout their pregnancy.
  • Diabetes can alter your body’s response to certain diseases. For example, diabetics who have heart attacks are more likely to present with atypical symptoms (and oftentimes present without chest pain altogether). This is likely partly due to nerve damage. Many diabetics have peripheral neuropathy, a nerve condition where they feel constant numbness and tingling in their toes and feet and have trouble recognizing pain in those limbs. These patients likely have nerve damage to other parts of their body, including their heart. The atypical symptoms lead to a delay in diagnosis of heart attacks.

Want to join the conversation?

  • leafers ultimate style avatar for user Kerr
    In reference to blood glucose levels, some foods are labeled low glycemic. What properties of such foods make it so? Is it simply the absence of sugar?
    (10 votes)
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    • spunky sam blue style avatar for user jose benavidez
      a low glycemic food just means it won't create a big spike in your blood glucose levels. Like if you eat potatoes they are really starchy so when that breaks down into glucose it make a big spike . So you feel hyper then tired. A low glycemic food like brown rice would give you slow but constant levels of energy as it breaks down .
      (24 votes)
  • piceratops ultimate style avatar for user Alexis  Harrington
    Is this a disease that is more likely to be inherited, lifestyle or environmental?
    (3 votes)
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    • piceratops tree style avatar for user Yasmeen.Mufti
      Type one is an autoimmune disease where the body attacks your beta cells in the pancreas, which means you cannot make insulin. The cause is unknown, although there are suspected genetic links.
      Type two is environmental, mostly, although you can have a genetic predisposition to it. Old age, sugary diet and lack of exercise are the hallmarks for type 11.
      (10 votes)
  • mr pink red style avatar for user Joao Gallotti
    Suppose a person has a predisposition to diabetes type 2, once there are many cases in his/her family. Having this in mind, if this person changes his/her lifestyle, trying to eat healthier and exercising, is it possible that this person will never have diabetes type 2?
    (2 votes)
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    • aqualine ultimate style avatar for user S.Shutak
      It is very possible that the person will not have DM type 2 if they live a healthy lifestyle, exercise regularly, and eat healthy while keeping a healthy weight. Generally, if you avoid the risk factors of a disease, you can avoid the disease. That being said though, there are many people who have been diagnosed with type 2 whose only risk factor was genetic predisposition.
      (6 votes)
  • aqualine tree style avatar for user Varsha Punati
    Do you get Type 1 Diabetes at birth of can this develop over time? If it does develop over time does the pancreas just stop producing insulin? Also what other endocrine diseases are there?
    (2 votes)
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  • boggle yellow style avatar for user starshine
    For type one diabetes, could increased urination be caused by increased thirst? I would assume increased thirst will result in drinking more water.
    (1 vote)
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    • leaf blue style avatar for user dysmnemonic
      There is a good observation here: how much water comes out should (roughly) match how much water goes in. It makes sense that taking in more water would mean that more urine is produced. The problem with this as an explanation is that we've just moved the problem, and now we need to work out why the patient is thirsty.

      Thirst happens for 2 main reasons: there's a decrease in circulating volume, or there's an increase in sodium concentrations. Both of these things reflect water leaving the body - so now our question is why the water is leaving.

      In diabetes we have a really good explanation for this: there's lots of sugar left in the renal filtrate, and that causes water to be drawn into the urine. Because there's lots of sugar, the sodium-glucose transporters can take most of the sodium back out of the urine. This means that there's lots of water leaving the body but most of the salt is staying behind - which then activates the reflexes for thirst. That thirst reflex then drives the extra drinking to replace all the water that's being lost in the urine.
      (5 votes)
  • starky tree style avatar for user Jose Rojas
    Why some pregnant develop gestational diabetes?
    (1 vote)
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    • leaf grey style avatar for user Abdelrahman
      One of the hormones released by the placenta is called Human Placental Lactogen. This protein increases insulin resistance in the mother, i.e. her cells do not respond as strongly to insulin, and so do not take up as much glucose, which makes sure that enough glucose is left behind for the baby.

      The decreased insulin uptake by the mother can result in higher levels of glucose in her blood than normal, which is termed gestational diabetes.

      It's perhaps interesting that human placental lactogen is not very potent under normal circumstances, but becomes important in conditions of starvation, when there is little glucose to go around, and so the placenta tries to reserve the baby's slice of the cake
      (3 votes)
  • leaf green style avatar for user aisha khan
    In this article, it says that in Type 2 Diabetes the body cells develop a certain resilience towards insulin, but I've also read that the pancreas does not produce enough insulin to control the blood sugar levels. These are two conflicting statements, which one is it?
    (1 vote)
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    • leaf green style avatar for user Joanne
      Sometimes it is useful to read an article a couple of times because the information is so dense, it is hard to comprehend. However, in this case, the problem is also complicated. In this article It says type 2 DIabetes mellitus is a continuum, that means the reasons causing the condition often change over time for the patient. It says the problem starts with the cells developing a resistance (not resilience) to insulin for reasons that are not fully understood. Over time, as the condition continues to affect the body, the pancreas slows down its production of insulin. So, both statements are true because the disease progresses, there is a continuum of symptoms and reasons for those symptoms.
      A person with Type 2 DM may be able to stop the progression with life style changes early on in the condition. However, if they do not, they start out with 'cellular resistance' to insulin and they progress to having a pancreas that ceases to make insulin. A type 2 will end up injecting insulin which is how a Type 1 starts out. Both statements are true, over time. Happy learning to you.
      (3 votes)
  • leaf green style avatar for user Russtudyent
    I heard somewhere that there is a diabetes 1.5 or 3. Does anyone know about it?
    (2 votes)
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  • duskpin sapling style avatar for user Hannah Martin
    Can people die from Diabetes?
    (1 vote)
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  • duskpin sapling style avatar for user Hannah Martin
    How can you help when you know that someone maybe in your family or a friend who has Diabetes and they get those symptoms that you have shown in this article? What can you do to help ?
    (1 vote)
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