Diabetic coma from high blood sugar

A diabetic coma from high blood sugar is a very specific condition. The medical name for this condition is Hyperglycemic Hyperosmolar Nonketotic Coma, or simply HONK. I have treated hundreds of patients hospitalized with diabetic comas from high blood sugar (HONK) over the last 15 years. I have written this article based on my personal experience as well as a thorough review of medical literature.

In this article, I will explain these things:

  1. Why dehydration is the key issue in a diabetic coma from high blood sugar
  2. How high your blood sugar has to be to get HONK
  3. Symptoms of diabetic comas from high blood sugar
  4. Why HONK mostly happens in Type 2 diabetics
  5. Who is at risk for a diabetic coma from high blood sugar
  6. What to expect when hospitalized for HONK

Why is dehydration the key issue in HONK?

Many people think that you can go into a diabetic coma if you don’t take care of your diabetes. However, that is only partially true. People who don’t take care of their diabetes are at risk for HONK, but you only go into a diabetic coma if you are dehydrated. If you are diabetic and become very dehydrated, you can go into a diabetic coma from high blood sugar even when you take good care of diabetes.

Just because you went into a diabetic coma from high blood sugar doesn’t mean you have poorly controlled diabetes. This is a simple fact that even many healthcare providers fail to understand. That is because we have been led to believe that bad things only happen to people with diabetes when they don’t take care of themselves. It may be true regarding long-term consequences of diabetes, but it’s not true for a diabetic coma from high blood sugar. As I will explain shortly, it can happen to anyone with diabetes.

When your blood sugars go up, you start to lose glucose in your urine. Glucose is highly soluble in water, so it draws water. When you lose glucose in the urine, you lose a lot of water with it. That is why people with uncontrolled diabetes are constantly thirsty and often urinating. Thirst is the body’s main defense preventing these people from going into HONK. As long as they keep drinking water, the blood sugar doesn’t rise to the level needed for a diabetic coma. Diabetics may have high blood sugars all the time, but if they are losing sugar and water in the urine while adding water to the body, these two processes balance out the blood sugar levels to make them high but not too high.

A diagram showing how high sugar in the blood leads to water loss and dehydration, causing a coma
A diagram showing how high sugar in the blood can lead to a coma

How high does your blood sugar have to be for a diabetic coma?

Your blood sugar has to be at least than 600mg/dl to have a risk of going into HONK. The average blood sugar in people with a diabetic coma is higher than 800mg/dl. It is not uncommon to see blood sugars higher than 1000mg/dl in a diabetic coma.

When your blood sugar gets this high, it means that the balancing act of drinking water and losing water in the urine has become unbalanced. Now you are losing more water than you are taking in. When this happens, it goes downhill fast.

As your blood sugars go higher, your blood becomes thick, like syrup. This draws water from your organs. The most significant effect happens on your brain. When the thick syrupy blood draws water from your brain, your brain shrinks. This triggers a series of symptoms that eventually lead to HONK.

What are the symptoms of a diabetic coma from high blood sugar?

It is important to note that very few patients with HONK are actually comatose. Without treatment, they might end up in a coma, but it is the end result of untreated HONK, not an early symptom. Symptoms get worse as the dehydration worsens and your brain shrinks further, eventually leading to a real coma. Here are the symptoms in order from mild to most severe:

  1. Headaches
  2. Weakness
  3. Nausea and vomiting
  4. Drowsiness
  5. Blurry vision
  6. Confusion and disorientation
  7. Seizures
  8. Involuntary movement of the arms and legs
  9. Stroke-like symptoms
  10. Entering a coma

Why does HONK usually happen in type 2 diabetics?

Unlike type 1 diabetics, type 2 diabetics still make insulin. Type 2 diabetics have high insulin resistance. It means that they need a lot of insulin to lower blood sugar just a little bit.

Blood sugars in type 1 diabetics rarely go as high as 600mg/dl. Blood sugars in type 1 diabetics go up because they don’t have insulin. Without insulin, the body can’t use sugars, and it starts making special acids called ketones. Too many ketones in the blood can cause severe acidosis, and leads to symptoms of diabetic acidosis, or DKA. Although some people lump DKA and HONK together as diabetic comas, they have very important differences. DKA is not truly a diabetic coma from high blood sugars. Blood sugars in DKA are rarely high enough to cause a coma. DKA can make you very sick, but the symptoms, risk factors, and treatments have very important differences. Do not mix up DKA and HONK.

Type 2 diabetics usually have enough insulin to prevent ketones but not enough insulin to bring blood sugars down effectively. They need too much insulin to do that because of the insulin resistance. That is why type 2 diabetics are more likely to have HONK, and type 1 diabetics are more likely to have DKA.

Who is at risk of HONK?

These are the people vulnerable to getting a diabetic coma from high blood sugars:

  1. Elderly diabetics living alone: In the United States, this is the group of people that are at the highest risk of going into a diabetic coma. Frequently, they fall down and can’t get up, or get too weak to get out of bed. When that happens, they may not have access to drinking water. As their blood sugars start to go up without access to water, they start to go into the spiral of events leading to a diabetic coma.
  2. People with a bad infection or sepsis: Sepsis is an overwhelming response of the body to an infection. Read “low blood pressure and fever: think sepsis” if you would like to learn more about sepsis. Sepsis causes your blood sugars to go up and makes you dehydrated. With dehydration and high sugars, sepsis can easily push you towards HONK.
  3. Diabetics who have recently had a major heart attack, major stroke, or a blood clot in the lungs: These are all very stressful on the body. When under stress, the body releases steroid hormones. These steroids raise blood sugars significantly, and push people towards a diabetic coma.
  4. Alcoholics or drug abusers: These people may not feel the thirst associated with high blood sugars, and may let themselves become dehydrated enough to spiral into HONK.
  5. People that didn’t know they had diabetes: A diabetic coma from high blood sugar may be the first sign of diabetes in these people. Type 2 diabetes starts slowly and worsens over the years. Some people may get used to the symptoms and feel like it is normal. They may feel the increased thirst, but may not think of it as a big deal. Some people have a habit of drinking sugary sodas when they are thirsty. If you drink sugary sodas when you are thirsty because of dehydration from high blood sugar, your blood sugar will rise even further and make you even more dehydrated than before. If you keep drinking sugary drinks, you will go into a diabetic coma. Most diabetics know they can’t do that when their sugars are already too high. If you have not been diagnosed, you may keep drinking the sugary soda without knowing what’s going on inside your body.

What should you expect when you are hospitalized for HONK?

Regardless of what pushed you into the diabetic coma, you will be admitted to the ICU. You will get specific treatments for any other major medical issues that you have along with HONK.

These are the most common things to expect in the hospital when hospitalized for a diabetic coma:

  1. A CT scan of the head
  2. A chest x-ray
  3. An EKG
  4. Multiple IV lines with lots of IV fluids
  5. Frequent blood tests
  6. IV insulin
  7. A ventilator if you are not awake enough to support your breathing
  8. A heart monitor

In conclusion, a diabetic coma from high blood sugar, or HONK, is a very important and specific condition that many people are not familiar with. It is important to understand the role of dehydration in HONK. A quick diagnosis and fast hospitalization is very important if you want to survive an episode of HONK.