What is Diabetes in Emergency Medicine?

Published on July 21, 2026

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The Three Major Diabetic Emergencies: Hypoglycemia, DKA, and HHS

In Emergency Medicine, diabetes-related emergencies range from mild symptoms to life-threatening conditions.

Significant elevations or reductions in blood sugar can affect the brain, heart, kidneys, and other organs, making timely recognition and treatment essential.

A common diabetes-related emergency is hypoglycemia, which occurs when a person’s blood glucose drops too low.

While there is no single blood sugar level at which every person develops symptoms, many clinicians consider a glucose level below 70 mg/dL to be hypoglycemia, with symptoms often becoming more pronounced as levels fall further.

On the opposite end of the spectrum are the two major hyperglycemic emergencies: diabetic ketoacidosis (DKA) and hyperglycemic hyperosmolar state (HHS).

DKA is characterized by elevated blood glucose, the accumulation of ketones, and metabolic acidosis, a condition in which excess acid builds up in the bloodstream.

HHS, by contrast, is characterized by profound hyperglycemia, severe dehydration, and hyperosmolality, meaning the blood becomes abnormally concentrated.

Unlike DKA, HHS generally does not involve significant ketoacidosis.

Patients with HHS frequently present with altered mental status ranging from confusion to coma, although symptoms can vary considerably from person to person.

DKA remains a common cause of hospitalization in the United States, accounting for more than 110,000 admissions annually.

Despite advances in treatment, reported mortality rates range from approximately 2% to 10%, depending on the patient population studied and the severity of illness at presentation.

HHS is less common than DKA but is associated with a substantially higher mortality rate, with some studies reporting mortality rates as high as 5% to 20%. Read more here.

Recognizing which of these conditions is present is important because the diagnosis guides the initial evaluation and treatment strategy in the emergency department.

Emergency Evaluation for Suspected Low or High Blood Sugar

When I suspect hypoglycemia (low blood sugar) or hyperglycemia (high blood sugar), I start with the same priorities I use for any emergency: airway, breathing, and circulation.

In other words, I first address whatever poses the most immediate threat to life.

Patients should expect an initial evaluation that may include oxygen if needed, heart monitoring, frequent vital signs, a bedside finger-stick glucose measurement, intravenous (IV) access, and an electrocardiogram (ECG).

The ECG is especially important because severe blood sugar abnormalities can be associated with electrolyte disturbances, such as abnormal potassium levels, which can affect the heart’s rhythm.

If a patient has altered mental status, the differential diagnosis extends beyond diabetes alone.

Emergency physicians simultaneously consider and evaluate for other potentially reversible causes, including medication effects, infections, nutritional deficiencies, and toxic exposures.

In some cases, treatment may begin before all test results are available if delaying therapy could place the patient at risk.

If a hyperglycemic emergency such as diabetic ketoacidosis (DKA) or hyperglycemic hyperosmolar state (HHS) is suspected, additional laboratory testing is typically performed.

This often includes blood tests to assess electrolytes, kidney function, acid-base balance, and blood cell counts, as well as urine tests.

Pregnancy testing is generally recommended for patients with childbearing potential because pregnancy can affect both the diagnosis and treatment plan.

For patients who appear critically ill or whose diagnosis is uncertain, further testing may be necessary.

Depending on the clinical situation, this can include measuring serum osmolality, lactate, magnesium, and phosphate levels, cardiac markers, and other studies aimed at identifying the underlying cause or evaluating for complications.

Just as importantly, emergency physicians try to determine why the blood sugar became dangerously abnormal in the first place.

A common way to remember the major triggers of DKA is the “Five I’s”:

• Infection – such as pneumonia or a urinary tract infection
• Infarction – including heart attacks or strokes
• Infant – pregnancy, which can significantly alter insulin requirements
• Indiscretion – such as substance abuse or major dietary changes
• Insulin lack – from missed doses, medication errors, or inadequate insulin therapy

Identifying and treating the underlying cause is often just as important as correcting the blood sugar itself.

Finally, physicians interpret laboratory results in the context of the patient’s hydration status and blood chemistry.

These calculations help distinguish DKA from HHS and guide the safest treatment strategy, topics we’ll explore in the next section.

Mechanisms That Distinguish DKA, HHS, and Medication-Related Hypoglycemia

DKA and HHS can look similar at first glance, but their underlying problems differ in ways that influence emergency treatment.

DKA results from a severe lack of effective insulin.

Without enough insulin, the body cannot use glucose normally and instead begins breaking down fat for energy, producing acidic compounds called ketones.

The combination of dehydration, elevated blood sugar, ketone production, and metabolic acidosis can quickly become life-threatening.

Treatment generally involves intravenous fluids, insulin, and careful monitoring of electrolytes.

HHS, by contrast, is characterized by extreme elevations in blood sugar and profound dehydration, leading to an abnormally concentrated blood state called hyperosmolality.

Unlike DKA, HHS usually does not involve significant ketone production or acidosis.

Early treatment focuses heavily on fluid replacement, and in some patients, blood sugar begins to improve substantially with fluids alone before insulin therapy becomes necessary.

For hypoglycemia, emergency care often centers on identifying the underlying cause, and medications are among the most common culprits.

Insulin can cause hypoglycemia because of dosing errors, missed meals, changes in physical activity, or, less commonly, intentional overdose.

Certain oral diabetes medications, known as insulin secretagogues, can also cause low blood sugar.

These include the sulfonylureas and meglitinides, which stimulate the pancreas to release insulin.

Sulfonylureas, in particular, can cause prolonged or recurrent hypoglycemia because their effects may last for many hours.

By contrast, medications such as metformin, alpha-glucosidase inhibitors, and thiazolidinediones rarely cause hypoglycemia when used alone because they do not directly stimulate insulin release.

Across all of these diabetic emergencies, potassium deserves special attention.

Potassium is an essential electrolyte that helps regulate muscle and nerve function, including the electrical activity of the heart.

Because insulin drives potassium from the bloodstream into cells, physicians carefully monitor potassium levels during treatment.

If potassium is already low, insulin therapy can worsen the deficit and, in some cases, contribute to dangerous heart rhythm abnormalities.

Treatment Hazards, Monitoring, and Disposition

Treating DKA and HHS is not simply a matter of “lowering the blood sugar.” Emergency teams must also manage dehydration, electrolyte imbalances, acid-base disturbances, and the underlying trigger of the crisis.

In DKA, insulin is essential because it helps stop ketone production and correct the acidosis.

However, insulin also moves potassium from the bloodstream into cells, which can make a low potassium level more dangerous.

For that reason, clinicians generally assess hydration status and potassium levels before starting insulin and monitor electrolytes closely during treatment.

Potassium can change significantly during DKA care.

Some patients initially have elevated potassium levels, which can affect the heart’s rhythm early in treatment.

Later, as fluids and insulin are given, potassium may fall and require replacement.

Because of these shifts, patients are typically placed on cardiac monitoring, and blood tests are repeated frequently until the situation is stable.

In hyperglycemic emergencies, bedside glucose is also checked frequently.

In DKA, once the glucose level improves, dextrose is often added to IV fluids so insulin can safely continue while ketones and acidosis resolve.

In HHS, fluid replacement is especially important because severe dehydration and hyperosmolality are central features of the condition.

As glucose and osmolality improve, clinicians monitor carefully for changes in kidney function, cardiovascular status, and mental status.

Most patients with DKA or HHS require hospital admission rather than discharge from the emergency department.

They need ongoing monitoring of glucose, electrolytes, hydration status, kidney function, and neurologic status until the crisis has clearly resolved.

Hypoglycemia is different.

Some patients with a single, easily explained episode that quickly corrects may be safe for discharge after a period of observation.

In general, clinicians look for stable blood sugar, the ability to eat, low risk of recurrence, reliable home monitoring, responsible supervision when appropriate, and follow-up.

Admission is more likely when hypoglycemia is recurrent, prolonged, difficult to reverse, related to long-acting insulin or sulfonylureas, associated with serious illness, or caused by overdose or self-harm.

Symptomatic hypoglycemia also raises safety concerns such as driving risk, so discharge instructions should address when it is safe to resume driving and other potentially hazardous activities.

ED Treatment Sequences for Hypoglycemia and Hyperglycemic Crisis, Plus Immediate Follow-Up

For hypoglycemia, the first priority is to confirm the diagnosis and treat it without delay.

A bedside glucose measurement is usually available within seconds.

If a patient is awake, able to swallow, and can protect their airway, treatment may be as simple as giving oral sugar followed by food.

If confusion, drowsiness, or loss of consciousness makes oral intake unsafe, intravenous (IV) dextrose is typically the fastest and most reliable treatment.

When IV access is not immediately available, glucagon given by injection is another option, although it may take longer to work and can cause nausea or vomiting.

Treatment does not end when the blood sugar initially improves.

In some patients, particularly those taking insulin or certain oral diabetes medications, the medication’s effect may outlast the initial glucose-lowering effect.

These patients may require repeated glucose checks, additional dextrose, prolonged observation, or hospital admission to prevent recurrent hypoglycemia.

For suspected DKA or HHS, emergency teams begin by stabilizing the airway, breathing, and circulation, then focus on correcting dehydration and metabolic abnormalities.

Intravenous fluids are a cornerstone of treatment for both conditions, although the timing and role of insulin differ between DKA and HHS.

In DKA, insulin is essential because it stops ketone production and helps reverse the underlying metabolic disturbance.

In HHS, aggressive fluid replacement is particularly important, and insulin therapy may be introduced based on the patient’s clinical response and laboratory findings.

Throughout treatment, clinicians closely monitor electrolytes, especially potassium, because insulin and fluid therapy can significantly alter potassium levels.

Both high and low potassium can affect the heart’s electrical system and, in severe cases, lead to dangerous arrhythmias.

Frequent reassessment and laboratory monitoring are therefore essential parts of safe care.

Additional treatments are tailored to the individual patient and the severity of illness.

Just as important as correcting the blood sugar is identifying and treating the underlying cause, whether that is infection, medication changes, heart disease, pregnancy, or another medical condition.

Finally, the emergency department visit is often only the beginning of the process.

Some patients are diagnosed with diabetes or prediabetes for the first time during an emergency evaluation, while others require changes to their medications or closer outpatient monitoring.

Before discharge, clinicians discuss abnormal results, review warning signs that should prompt a return to the emergency department, and arrange appropriate follow-up to help reduce the risk of future emergencies.

That follow-up plan closes the loop between emergency stabilization and the long-term management that diabetes requires.

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