Hyperosmolar Hyperglycemic State (HHS) - EMT Student Guide

Based on: Rosen's Emergency Medicine (9e), Harrison's Principles of Internal Medicine (22e, 2025), Goldman-Cecil Medicine, and the Joint British Diabetes Societies (JBDS) 2023 Updated Guideline.

1. Definition

• Severe hyperglycemia (blood glucose >600 mg/dL [>33.3 mmol/L])
• Extreme dehydration and hyperosmolality (>320 mOsm/kg)
• Minimal or absent ketoacidosis
• Altered mental status that may progress to coma

2. Epidemiology & Risk Factors

• Most common in elderly patients with Type 2 diabetes (majority >65 years old), but increasingly seen in younger adults and children as T2DM rates rise
• Mortality is significantly higher than DKA - up to 15-20% - largely due to underlying precipitating illness and comorbidities
• Onset is gradual over days to weeks (much slower than DKA)
• Can occur in non-diabetic patients (e.g., after burns, parenteral hyperalimentation, dialysis)

3. Causes & Precipitating Factors

• Infections (pneumonia, urinary tract infection, sepsis - most frequent triggers)
• Inadequate insulin treatment or medication non-adherence
• New-onset, previously undiagnosed diabetes
• Acute coronary syndrome / myocardial infarction
• Cerebrovascular accident (stroke)

• Acute pancreatitis
• Pulmonary embolism
• Severe burns / hyperthermia
• Medications: corticosteroids, thiazide diuretics, sympathomimetics, atypical antipsychotics (clozapine, olanzapine), lithium, cocaine
• Impaired cognition or physical disability preventing adequate fluid intake (dementia, prior stroke, nursing home residents)

4. Pathophysiology (Simplified for EMT)

1. Relative insulin deficiency --> liver produces excess glucose (glycogenolysis + gluconeogenesis) + muscles can't use glucose
2. Extreme hyperglycemia --> draws water out of cells into bloodstream (osmotic effect), temporarily preserving circulation
3. Osmotic diuresis --> kidneys dump massive amounts of glucose + water in urine (polyuria)
4. Progressive dehydration --> fluid deficits can reach 9-12 liters in adults
5. Decreasing kidney perfusion --> GFR drops, glucose can no longer be excreted, worsening hyperglycemia
6. Blood becomes hyperosmolar --> brain cells shrink, causing neurological dysfunction
7. Minimal ketosis: small residual insulin secretion blocks ketone formation in the liver (unlike DKA where insulin is completely absent)

5. Signs & Symptoms

Prodromal Phase (Days to Weeks Before)

• Polydipsia (extreme thirst)
• Polyuria (frequent, large-volume urination)
• Polyphagia initially, then anorexia
• Progressive weakness and fatigue
• Unintentional weight loss
• Increasing confusion / behavioral changes

By the Time EMS Arrives (Acute Presentation)

• Altered mental status - ranging from mild confusion/lethargy to deep coma (more severe than DKA)
• Focal neurological deficits mimicking stroke (hemiparesis, aphasia, visual changes)
• Seizures (focal or generalized)
• Sunken eyes, sluggish pupils

• Tachycardia (pulse >100 bpm)
• Hypotension (systolic <100 mmHg) - sign of severe volume depletion
• Weak/thready pulse
• Cool, mottled extremities (late sign of circulatory compromise)

• Extremely dry mucous membranes, dry/cracked lips
• Sunken eyes
• Poor skin turgor (tenting)
• Longitudinal furrows on the tongue
• Decreased or absent urine output (late)

• Respirations may be normal or slightly rapid - notably NO Kussmaul respirations (deep, gasping breathing) unlike DKA
• No fruity/acetone odor to the breath

• Nausea/vomiting are minimal or absent (key contrast with DKA)
• No abdominal pain (if present, consider mixed DKA/HHS or pancreatitis)

• Fever may or may not be present (suggests infection)
• Normothermia or even hypothermia can occur

Key Clinical Pearl for EMTs: A patient appearing like a "stroke" in a known diabetic - especially elderly, severely dehydrated, with glucose >600 mg/dL and NO Kussmaul breathing - should raise strong suspicion for HHS.

6. HHS vs. DKA - Quick Comparison Table

7. Prehospital Clinical Assessment (EMT Approach)

Scene Size-Up & Primary Survey (ABCDE)

1. Airway - Assess and maintain; altered mental status = risk of aspiration; position patient appropriately; suction if needed
2. Breathing - Rate and quality; note absence of Kussmaul respirations; apply supplemental oxygen if SpO2 <94%
3. Circulation - Check pulse rate/quality; skin color/temp/moisture; capillary refill; assess for shock
4. Disability (Neurological) - AVPU or GCS; pupils; blood glucose measurement; look for focal deficits
5. Exposure - Look for medical alert jewelry, insulin pump, signs of infection, skin ulcers

History (SAMPLE)

• Signs/Symptoms: onset, duration, progression of confusion, polyuria, polydipsia, weakness
• Allergies
• Medications: insulin, oral hypoglycemics, steroids, diuretics, antipsychotics
• Past medical history: Type 2 diabetes, dementia, prior stroke, renal disease, recent illness
• Last oral intake: when did patient last drink/eat? (often days of poor intake)
• Events leading up: recent infection, fever, missed medications, dietary changes

Vital Signs

• Full vital signs including blood glucose (field glucometry)
• SpO2, respiratory rate, mental status scoring
• 12-lead ECG if available (rule out MI as precipitant, detect electrolyte changes - peaked T-waves in hyperkalemia)

Focused Physical Exam

• Skin assessment for dehydration (turgor, mucous membranes, eyes)
• Neuro exam: GCS, focal deficits
• Abdominal exam: tenderness suggests pancreatitis or mixed DKA/HHS
• Look for source of infection: breath sounds (pneumonia), abdominal tenderness, skin wounds, urinary symptoms

8. Prehospital Management (EMT / EMS)

Core Principle: HHS is a true medical emergency requiring rapid transport. The primary EMT interventions are airway protection, IV fluid resuscitation initiation, glucose monitoring, and rapid notification of receiving facility.

Step-by-Step Prehospital Care

• BSI/PPE; position patient for safety (recovery position if unconscious but breathing)

• If unconscious: open airway (head-tilt chin-lift or jaw thrust); consider OPA/NPA
• Suction as needed (aspiration risk)
• Apply supplemental O2 if SpO2 <94% or respiratory distress
• Be prepared to assist ventilations or intubate (ALS) if respiratory failure

• Establish large-bore IV access (18g or larger, two lines preferred)
• Begin 0.9% Normal Saline (NS) - initial fluid of choice for hemodynamic stabilization
• If patient is in shock (hypotension, poor perfusion): give 500-1000 mL NS bolus, reassess
• If stable: begin NS infusion at 250-500 mL/hr during transport
• CAUTION: Do NOT over-resuscitate rapidly - brain injury risk from too-fast osmolality correction; this is especially important in elderly patients
• Fluid deficit is typically 9-12 L; full correction happens over 24-48 hours in-hospital

• Obtain fingerstick blood glucose
• Do NOT give dextrose (D50W) - patient already severely hyperglycemic
• If blood glucose >600 mg/dL with signs/symptoms consistent with HHS, treat as HHS

• Attach cardiac monitor - watch for dysrhythmias
• Obtain 12-lead ECG to evaluate for MI (common precipitant), and to assess for hyperkalemia/hypokalemia signs

• Insulin management is complex in HHS (risk of rapid osmolality shifts causing cerebral edema)
• In most EMS protocols, insulin is a hospital-initiated intervention
• Exception: follow your local medical director's protocols if standing orders exist

• Check temperature - fever suggests infection (most common precipitant)
• Keep patient warm; these patients are often elderly and prone to hypothermia

• If patient seizes: protect from injury, maintain airway, follow seizure protocol
• Do NOT give dextrose or thiamine (not hypoglycemia)
• Benzodiazepines per protocol if prolonged seizure (ALS)

• This patient needs the ED, ICU, or monitored setting
• Give early radio report: "Elderly diabetic, blood glucose >600, altered mental status, signs of severe dehydration, suspect HHS"
• Estimated fluid deficit, mental status, vital signs, IV access/fluids running

• Reassess every 5 minutes: ABCs, mental status, vital signs
• Reassess glucose and fluid response
• Document all findings and times

9. In-Hospital Management Overview (for context)

• Serum osmolality <300 mOsm/kg
• Blood glucose <250 mg/dL (15 mmol/L)
• Urine output >0.5 mL/kg/hr (hydration restored)
• Mental status returned to baseline
• Able to tolerate oral fluids

10. Complications to Watch For

• Cerebral edema - caused by too-rapid osmolality correction; more risk in younger patients
• Deep vein thrombosis / Pulmonary embolism - HHS causes hypercoagulable state; prophylaxis recommended
• Acute kidney injury - from severe dehydration and osmotic diuresis
• Rhabdomyolysis - muscle breakdown from severe dehydration
• Dysrhythmias - from electrolyte abnormalities (hypokalemia, hyponatremia)
• Hypoglycemia - during treatment if insulin/fluids are managed too aggressively

11. Key EMT Takeaways

1. HHS = severe hyperglycemia + extreme dehydration + altered mental status + NO significant ketoacidosis
2. The patient is often elderly, type 2 diabetic, with symptoms developing over days to weeks
3. Do NOT confuse with stroke - HHS can present with focal neurological deficits
4. Fluids first - aggressive but controlled IV fluid resuscitation is the cornerstone of treatment
5. No insulin prehospital (unless per protocol)
6. No dextrose - do not worsen hyperglycemia
7. Always search for the precipitating cause (infection, MI, stroke, missed meds)
8. Rapid transport; early hospital notification; monitor and reassess continuously
9. Mortality is high (up to 20%) - take this patient seriously

• Rosen's Emergency Medicine: Concepts and Clinical Practice, 9e - Ch. HHS
• Harrison's Principles of Internal Medicine, 22e (2025) - Ch. 416
• Goldman-Cecil Medicine, International Edition - Ch. 210
• JBDS (Joint British Diabetes Societies) Updated Guideline on HHS in Adults, 2023 (PMC10107355)
• ADA Standards of Care in Diabetes, 2025 / Consensus Report 2024