How does hyperosmolar hyperglycemic state present clinically?

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Last updated: October 29, 2026 • View editorial policy

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How HHS Presents Clinically

HHS typically evolves insidiously over several days to weeks with profound dehydration, marked hyperglycemia, and altered mental status ranging from lethargy to coma—a much slower onset than DKA's 24-hour evolution 1.

Timeline and Evolution

The presentation unfolds gradually over days to weeks, giving patients time to develop severe metabolic derangement before seeking care 1. This contrasts sharply with DKA, which develops within 24 hours.

Classic Symptoms (History)

Patients report a constellation of hyperglycemic symptoms:

  • Polyuria (excessive urination from osmotic diuresis)
  • Polydipsia (extreme thirst)
  • Polyphagia (increased hunger)
  • Weight loss
  • Weakness and fatigue
  • Progressive clouding of consciousness 1

Critical distinction: Vomiting and abdominal pain are typically absent in HHS (these occur in DKA) 1.

Physical Examination Findings

Dehydration Signs (Profound)

  • Poor skin turgor (severe volume depletion)
  • Dry mucous membranes
  • Tachycardia
  • Hypotension (may progress to shock) 1, 2

Fluid losses are massive: 100-220 mL/kg 3.

Neurological Manifestations

Mental status changes are the hallmark of HHS and occur more frequently than in DKA 1:

  • Full alertness (early)
  • Lethargy
  • Profound confusion
  • Coma (more common in HHS than DKA)

The degree of altered consciousness correlates with serum osmolality 2.

Respiratory Pattern

Kussmaul respirations are ABSENT in HHS (this distinguishes it from DKA, where deep rapid breathing compensates for acidosis) 1.

Temperature

  • Patients are typically normothermic or even hypothermic despite infection being the most common precipitant
  • Peripheral vasodilation causes this paradoxical finding
  • Hypothermia is a poor prognostic sign 1

Diagnostic Criteria

The biochemical triad defines HHS 1:

  • Plasma glucose ≥600 mg/dL (≥30 mmol/L)
  • Effective serum osmolality ≥320 mOsm/kg [calculated as: (2×Na⁺) + glucose + urea]
  • Arterial pH >7.30 (no significant acidosis)
  • Serum bicarbonate ≥15 mEq/L
  • Minimal or absent ketones (≤3.0 mmol/L)

At-Risk Populations

Elderly patients are particularly vulnerable, especially:

  • Nursing home residents
  • Those with new-onset type 2 diabetes
  • Patients unable to access fluids independently
  • Those unaware of their hyperglycemia 1

Common Precipitants to Identify

Infection is the most common trigger 1. Other precipitants include:

  • Cerebrovascular accident (stroke)
  • Myocardial infarction
  • Pancreatitis
  • Trauma
  • Medications: corticosteroids, thiazides, sympathomimetics (dobutamine, terbutaline)
  • Non-adherence to diabetes medications

Critical Pitfalls

  1. Don't assume fever with infection: Patients may be normothermic or hypothermic despite serious infection 1
  2. Altered mental status severity varies: Don't rule out HHS because the patient is alert 1, 2
  3. Mixed presentations exist: Some patients have overlapping DKA/HHS features 3
  4. Mortality is high (15%), worse than DKA (5%), especially with coma and hypotension 1

Prognosis Indicators

Poor prognostic factors include:

  • Extremes of age
  • Presence of coma
  • Hypotension
  • Hypothermia 1

The mortality rate remains 15% even with proper management, significantly higher than DKA 1.

References

1
Guideline

hyperglycemic crises in diabetes.

Diabetes Care, 2004

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