Hyperosmolar hyperglycemic state (HHS) is a serious complication of diabetes that happens when blood sugar levels are very high for a long period of time. Symptoms of HHS can include extreme thirst, frequent urination and confusion. HHS is an emergency that requires immediate medical care.
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Hyperosmolar hyperglycemic state (HHS) is a life-threatening complication of diabetes — mainly Type 2 diabetes. HHS happens when your blood glucose (sugar) levels are too high for a long period, leading to severe dehydration and confusion.
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Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy
HHS requires immediate medical treatment. Without treatment, it can be fatal.
Diabetes-related ketoacidosis (DKA) and hyperosmolar hyperglycemic state (HHS) are both life-threatening diabetes complications related to high blood sugar (hyperglycemia), but they’re different conditions.
DKA happens when your body doesn’t have enough insulin. Your body needs insulin to turn glucose, your body’s go-to source of fuel, into energy. If there’s no insulin or not enough insulin, your body starts breaking down fat for energy instead. As your body breaks down fat, it releases ketones into your bloodstream. Ketones cause your blood to become acidic, which is life-threatening.
HHS happens when very high blood sugar leads to severe dehydration and highly concentrated blood (high osmolality), which are life-threatening. HHS also involves a lack of insulin, but the person usually still produces enough insulin to prevent the production of ketones. In addition, there’s usually an underlying condition, such as an infection, that’s also contributing to the high blood sugar.
The main difference between DKA and HHS is that DKA involves ketones and blood acidity; HHS doesn’t. The two complications have similar symptoms, including intense thirst, frequent urination and mental status changes.
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Differences between DKA and HHS include:
Markers | DKA | HHS |
---|---|---|
People affected. | Most commonly affects people with Type 1 diabetes. | Most commonly affects people with Type 2 diabetes. |
Time to develop. | Develops quickly — often within 24 hours. | Develops more slowly — usually within days to weeks. |
Blood sugar level. | Usually above 250 mg/dL. | Higher than 600 mg/dL. |
Urine or blood ketones. | Present. | Trace or none. |
Blood pH level. | 7.3 or lower. | Higher than 7.3. |
Mortality rate. | About 1% to 8%. | About 10% to 20%. |
Markers | ||
People affected. | ||
DKA | ||
Most commonly affects people with Type 1 diabetes. | ||
HHS | ||
Most commonly affects people with Type 2 diabetes. | ||
Time to develop. | ||
DKA | ||
Develops quickly — often within 24 hours. | ||
HHS | ||
Develops more slowly — usually within days to weeks. | ||
Blood sugar level. | ||
DKA | ||
Usually above 250 mg/dL. | ||
HHS | ||
Higher than 600 mg/dL. | ||
Urine or blood ketones. | ||
DKA | ||
Present. | ||
HHS | ||
Trace or none. | ||
Blood pH level. | ||
DKA | ||
7.3 or lower. | ||
HHS | ||
Higher than 7.3. | ||
Mortality rate. | ||
DKA | ||
About 1% to 8%. | ||
HHS | ||
About 10% to 20%. |
It’s difficult for researchers to determine how common HHS is, but they think it’s relatively uncommon compared to other diabetes-related complications. Some studies show that about 1% of all hospital admissions for diabetes are due to HHS.
Symptoms of HHS usually come on slowly and can take days or weeks to develop. Symptoms include:
If you or a loved one are experiencing these symptoms, get to the nearest emergency room.
Hyperosmolar hyperglycemic state happens when very high blood sugar leads to severe dehydration, highly concentrated blood and mental status changes.
If you manage diabetes well, your risk of developing HHS is low. But certain conditions and situations can trigger HHS to develop in people who aren’t managing diabetes well.
Common triggers of HHS include:
When you have high blood sugar, your kidneys try to get rid of the excess sugar through your pee. Through this process, you also lose fluids (water) that your body needs.
If your blood sugar remains elevated for a long period of time, it leads to dehydration through frequent peeing. It also causes your blood to become more concentrated than normal. This is called hyperosmolarity. These health complications meet the criteria for HHS.
HHS mainly affects people with Type 2 diabetes, typically adults older than 65 years. If diabetes is well managed, your risk of HHS is low.
The following factors can increase your risk of developing HHS:
If HHS isn’t treated in time, it can lead to the following complications:
Approximately 10% to 20% of cases result in death.
You should seek medical attention right away if you have symptoms of HHS.
At the hospital, a healthcare provider will perform a physical exam and ask about your symptoms. They’ll order blood tests, such as a comprehensive metabolic panel, to check your blood sugar level and other measurements of your health.
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A blood sugar level over 600 mg/dL (33 mmol/L) with low ketone levels points to a diagnosis of HHS.
To treat HHS, a healthcare provider will give you IV (intravenous) medications. These include:
Your healthcare team will also treat any underlying conditions or infections that may have caused the HHS. You’ll likely have to stay in the hospital at least overnight so your healthcare team can watch you closely for any complications.
The main possible complication of HHS treatment is if your blood sugar level drops too quickly. If it lowers rapidly, it can cause sudden shifts of fluid within your brain and lead to brain swelling (cerebral edema).
This is a rare complication, however. Healthcare providers know how to slowly and safely lower your blood sugar level.
The best way to prevent HHS is by following a healthy lifestyle and managing your diabetes. You should:
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The prognosis (outlook) for people with HHS largely depends on:
Up to 20% of people who have HHS die from the condition. People who develop coma and/or low blood pressure have a poorer prognosis.
HHS is a serious medical condition. If you have diabetes, you should call 911 or seek emergency medical help if you:
If you’ve had HHS, you’ll need to work closely with your provider once you’re home from the hospital. You can reduce your risk of developing HHS again by managing your diabetes, your diet and your lifestyle.
A note from Cleveland Clinic
Hyperosmolar hyperglycemia state (HHS) is a serious and life-threatening condition, so acting fast if you’re experiencing symptoms is very important. Call 911 or go to the nearest emergency room if you experience symptoms. Diabetes complications can be scary. Being educated and prepared are crucial to preventing HHS. Don’t be afraid to ask your healthcare provider questions about HHS or your diabetes management.
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Last reviewed on 02/17/2023.
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