Hyperglycemic hyperosmolar nonketotic syndrome (HHNS) is also known as hyperglycemic hyperosmolar syndrome (HHS). It involves very high blood sugar levels and can be life threatening.

HHNS can happen to anyone, but it’s more common in older people who have type 2 diabetes.

If your blood sugar gets too high, your kidneys try to excrete excess sugar through urination. When this happens, it’s known as hyperglycemia.

But if you do not drink enough to replace the fluid you’ve lost, blood sugar levels get even higher and your blood becomes more concentrated. This is called hyperosmolarity. Blood that is too concentrated starts to take water from other organs, including your brain.

Diabetic ketoacidosis (DKA) is a complication of type 1 diabetes and, less commonly, type 2 diabetes. When your blood sugar is very high, ketones (acidic substances) can accumulate in your blood at dangerous levels, causing DKA.

DKA typically evolves within a few hours, whereas HHNS is much slower and occurs over days to weeks, according to 2021 research. The two conditions look similar because of the hyperglycemia component of each condition.

Knowing the symptoms of each can help you seek medical care as soon as possible.

Symptoms of HHNS can include:

  • very high blood sugar levels
  • dry mouth
  • fast heart rate
  • thirst
  • frequent urination
  • nausea, vomiting, or stomachache
  • confusion, slurred speech, or weakness on one side of your body

Symptoms of DKA can include:

If you have symptoms of either condition, seek emergency care immediately.

High blood sugar levelsXX
Extreme thirstXX
Frequent urinationXX
High ketone levels in urineX
Fruity-smelling breathX
Rapid breathingX
Fast heart rateX
Slurred speech X
One-sided weaknessX

Knowing the potential causes of HHNS and DKA can help you take steps to reduce the risk of developing either condition.

Possible factors that can lead to HHNS include:

  • very high blood sugar levels from undiagnosed or unmanaged diabetes
  • substance misuse
  • coexisting conditions
  • infections, such as pneumonia, urinary tract infection, or sepsis
  • certain medications, especially second-generation drugs for psychosis
  • not following a diabetes treatment plan

For people who have diabetes, possible factors that can cause DKA include:

  • infections
  • illnesses
  • psychological stress
  • clogs in an insulin pump if you have one
  • missing an insulin injection or not following your treatment plan
  • pregnancy

Both HHNS and DKA are serious conditions and need immediate treatment.

A medical professional can typically treat HHNS using four steps:

  • giving you fluids through an IV
  • helping you manage your electrolytes
  • giving you insulin through an IV
  • diagnosing and managing the causes, and determining if there is a coexisting condition

If you experience any complications from HHNS, like shock, the medical professional will also treat these.

Your treatment for DKA is similar to that of HHNS. The medical professional will:

  • replace your fluids through an IV
  • treat your insulin
  • help you manage your electrolytes

If there is any underlying cause of DKA, like an infection or other illness, your doctor can help you identify and address it.

While you might not always be able to prevent some causes of HHNS or DKA, like an illness or infection, there are steps you can take to reduce the risk of these conditions occurring. These include:

  • taking prescribed medications regularly and consistently
  • eating a balanced diet
  • checking blood sugar levels regularly
  • staying hydrated
  • wearing a medical alert bracelet for diabetes
  • sharing warning signs with co-workers, friends, family, and neighbors so they can help you if you are unaware of the warning signs
  • seeing your doctor regularly for checkups

Talk with your doctor to find out which specific symptoms you should watch for and what to do. If you become sick with an infection, you can ask your doctor if there are certain steps to take to help prevent HHNS or DKA.

If you notice that your blood sugar levels are higher than usual, call your doctor. Let them know what is going on and whether you have any other symptoms.

If you start to have symptoms of HHNS or DKA, call 911 or go to your local emergency room immediately. These are serious medical events that can lead to life threatening complications if left untreated.

While HHNS and DKA are serious medical conditions that can lead to life threatening complications, they are preventable and treatable, especially if you identify them early.

Following a treatment plan, staying hydrated, and monitoring your body for any unusual symptoms can all help reduce your risk of developing these conditions.