HHS vs. DKA: What Are the Differences?

Table of Contents
View All
Table of Contents

Hyperosmolar hyperglycemic syndrome (HHS) and diabetic ketoacidosis (DKA) are two serious diabetic complications. Both conditions cause very high blood sugar levels, but there are essential distinctions between the two.

Learn more about the differences between HHS and DKA, including the symptoms, causes, and diagnosis. This article will also discuss HHS and DKA treatment and prevention.

diabetes monitoring

Maskot / Getty Images


The symptoms of HHS and DKA are very similar.

DKA tends to produce symptoms slowly, with thirst and frequent urination happening first. If treatment does not occur, severe symptoms will quickly progress.

HHS progresses slowly over weeks. The symptoms look like DKA but can also include neurological changes like confusion.

Here is a list of all the DKA and HHS symptoms:

  • Increased thirst

  • Frequent urination

  • Dry mouth

  • Nausea

  • Fever

  • Weight loss

  • Weakness

  • Confusion

  • Slurred speech

  • Face flushing

  • Increased thirst

  • Frequent urination

  • Dry mouth

  • Nausea and vomiting

  • Headache

  • Decreased alertness

  • Face flushing

  • Fruity-smelling breath

  • Weight loss

  • Fever

When HHS and DKA continue untreated, it can lead to serious complications like:

  • Seizures
  • Loss of muscle function
  • Speech impairment
  • Coma
  • Death


DKA and HHS have similar causes. They both occur when insulin does not work effectively, which results in dangerously high blood sugar levels. However, key differences between the two conditions are highlighted below.

Causes of HHS

HHS is most commonly seen in people with type 2 diabetes.

When someone has high glucose levels, the body tries to get rid of it through the urine. However, this causes the body to lose too much fluid. If the water is not replenished or if the person continues to consume high-sugar drinks or high-carbohydrate foods, the person will become extremely dehydrated. With the lack of fluids, the body will not be able to continue getting rid of the extra sugar, resulting in very high blood glucose levels.

Dehydration from HHS also results in high sodium levels, pulling more water out of the tissues and organs.

The primary cause of HHS is infection. Infection accounts for 50% to 60% of all HHS cases due to the dehydration and release of catecholamines like dopamine, epinephrine, and norepinephrine.

Other causes of HHS include:

  • Heart attack or stroke
  • Not taking diabetes medicines
  • Diuretics or other medications that cause fluid loss
  • Medications that lessen the effect of insulin

HHS is often considered worse than DKA due to its higher mortality rates.

Causes of DKA

DKA is typically seen in people with type 1 diabetes.

DKA occurs when insulin levels are low or nonexistent. Without insulin, glucose cannot move into cells to provide energy and fuel. As a result, the body breaks down fat into ketones to use as fuel. However, the body breaks down the fat too fast, and ketones build up in the blood. This causes ketoacidosis.

DKA is caused by:

  • Undiagnosed type 1 diabetes
  • Infection
  • Injury or illness
  • Missing insulin doses
  • Surgery

One of the unique features of DKA is that people with the condition have increased ketone levels. This causes one of DKA's most unusual symptoms, fruity-smelling breath.


DKA and HHS are diagnosed in similar ways. Both conditions will use blood tests to evaluate blood glucose, electrolyte levels, pH (blood acidity), and ketones.

People with DKA have high blood glucose and dangerously low pH levels, indicating high blood acidity. They also are positive for ketones in their urine and blood.

People with HHS tend to have much higher blood glucose levels than those with DKA. It can be 600 milligrams per deciliter (mg/dL) or higher. They also have very high serum osmolality levels (the concentration of chemical particles in the blood).

In those with HHS, there is still a small amount of insulin production, which blocks the development of ketones. This is why there are ketone levels are low or zero in those with HHS.

Other diagnostic tools that may be used in those with DKA and HHS include:


DKA and HHS are very serious conditions that will need to be treated in a hospital. Their treatments are very similar. Both conditions will need:

  • Fluid replacement: Fluids will be given through an intravenous (IV) to correct dehydration.
  • Insulin: Insulin is given to very slowly bring down blood glucose levels.
  • Electrolyte replacement: Minerals needed for muscles, heart, and brain can be low with HHS and DKA and will be replaced as needed.
  • Medications: If HHS or DKA had an underlying cause of an illness or infection, it may be treated with medicines like antibiotics.


DKA and HHS are serious conditions. Here are ways to prevent it from happening:

  • Take diabetes medication as prescribed.
  • Keep blood sugar levels in a normal range.
  • If sick, check blood sugar levels more frequently.
  • Talk to a healthcare provider about changing insulin dose or frequency based on activity levels and foods consumed.


DKA and HHS are two complications of diabetes. DKA is typically seen in people with type 1 diabetes, whereas HHS is typically seen in people with type 2 diabetes. These conditions cause an unsafe high blood glucose level, dehydration, and electrolyte changes. Those with DKA will also have high ketone levels. Treatment must be sought quickly to prevent serious complications, which can include death.

A Word From Verywell

If you have diabetes, it is important to understand how to take care of yourself properly. DKA and HHS are two conditions that can be caused by poor diabetes management. Take your medications as prescribed and talk to your healthcare provider if you become sick. If you suspect that you have DKA or HHS, seek emergency help immediately.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. Diabetic ketoacidosis.

  2. MedlinePlus. Diabetic ketoacidosis.

  3. MedlinePlus. Diabetic hyperglycemic hyperosmolar syndrome.

  4. Pasquel FJ, Tsegka K, Wang H, et al. Clinical outcomes in patients with isolated or combined diabetic ketoacidosis and hyperosmolar hyperglycemic state: a retrospective, hospital-based cohort studyDiabetes Care. 2020;43(2):349-357.

  5. Adeyinka A, Kondamudi NP. Hyperosmolar hyperglycemic syndrome. StatPearls.

By Patty Weasler, RN, BSN
Patty is a registered nurse with over a decade of experience in pediatric critical care. Her passion is writing health and wellness content that anyone can understand and use.