side by side comparison

DKA vs HHS: Two Diabetic Emergencies — Different Mechanisms, Different Presentations

Both DKA and HHS present with sky-high glucose, but picking the wrong distinguishing feature costs you the question. DKA kills with acidosis; HHS kills with dehydration and hyperosmolarity. The NCLEX expects you to match the right lab picture and clinical signs to the right emergency — fast.

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Comparison

Side-by-side2 compared
Dimension
DKA
HHS
Pathophysiology & risk
  • Absolute insulin deficit then ketoacidosis
  • Type 1 (or Type 2 under stress)
  • Rapid onset: hours to 1–2 days
  • Relative insulin deficit (blocks ketosis)
  • Type 2, usually older adults
  • Insidious onset: days to weeks
Signs & symptoms
  • ★Kussmaul respirations (deep, rapid)
  • Fruity (acetone) breath
  • Abdominal pain
  • Nausea/vomiting
  • Alert then confused, late coma
  • Profound dehydration (8–12 L deficit)
  • Altered level of consciousness
  • Seizures
  • Coma common at presentation
  • No Kussmaul or fruity breath
Diagnostics & labs
  • ★Serum ketones positive
  • Beta-hydroxybutyrate elevated
  • Glucose > 250 (often 300–500)
  • Arterial pH < 7.30 (acidosis)
  • Bicarbonate < 18
  • Elevated anion gap
  • ★Serum osmolality > 320
  • Ketones absent or trace
  • Glucose > 600 (often > 1,000)
  • Arterial pH > 7.30 (no acidosis)
  • Bicarbonate > 18
Nursing priorities
  • IV 0.9% normal saline resuscitation
  • ★Insulin only after K⁺ ≥ 3.3 mEq/L
  • Trend anion gap to closure
  • IV 0.9% normal saline resuscitation
  • ★Aggressive NS — fluids are top priority
  • Monitor serum osmolality
  • Monitor neurologic status
Treatment & meds
  • Regular insulin IV infusion
  • Add D5 when glucose ~200
  • Replace potassium (K⁺)
  • Replace phosphate
  • Switch to subcutaneous insulin when stable
  • Regular insulin IV infusion
  • Replace potassium (K⁺)
  • Insulin titrated more slowly
  • Treat the precipitating illness
Patient teaching
  • Never stop insulin
  • Follow sick-day rules
  • Check ketones when ill or glucose > 240
  • Stay hydrated during illness
  • Monitor glucose during illness
  • Maintain medication adherence
  • Infection is a common trigger
Red flags — escalate
  • Avoid rapid glucose correction
  • Hypokalemia as insulin shifts K⁺ into cells
  • Hypovolemic shock from severe dehydration
  • Hyperviscosity raises clot risk
Complications
  • Mortality ~1–5%
  • Cerebral edema (pediatric DKA)
  • Mortality ~10–20% (higher)
  • Venous thromboembolism (VTE)
Pathophysiology & risk

DKA

  • Absolute insulin deficit then ketoacidosis
  • Type 1 (or Type 2 under stress)
  • Rapid onset: hours to 1–2 days

HHS

  • Relative insulin deficit (blocks ketosis)
  • Type 2, usually older adults
  • Insidious onset: days to weeks
Signs & symptoms

DKA

  • ★Kussmaul respirations (deep, rapid)
  • Fruity (acetone) breath
  • Abdominal pain
  • Nausea/vomiting
  • Alert then confused, late coma

HHS

  • Profound dehydration (8–12 L deficit)
  • Altered level of consciousness
  • Seizures
  • Coma common at presentation
  • No Kussmaul or fruity breath
Diagnostics & labs

DKA

  • ★Serum ketones positive
  • Beta-hydroxybutyrate elevated
  • Glucose > 250 (often 300–500)
  • Arterial pH < 7.30 (acidosis)
  • Bicarbonate < 18
  • Elevated anion gap

HHS

  • ★Serum osmolality > 320
  • Ketones absent or trace
  • Glucose > 600 (often > 1,000)
  • Arterial pH > 7.30 (no acidosis)
  • Bicarbonate > 18
Nursing priorities

DKA

  • IV 0.9% normal saline resuscitation
  • ★Insulin only after K⁺ ≥ 3.3 mEq/L
  • Trend anion gap to closure

HHS

  • IV 0.9% normal saline resuscitation
  • ★Aggressive NS — fluids are top priority
  • Monitor serum osmolality
  • Monitor neurologic status
Treatment & meds

DKA

  • Regular insulin IV infusion
  • Add D5 when glucose ~200
  • Replace potassium (K⁺)
  • Replace phosphate
  • Switch to subcutaneous insulin when stable

HHS

  • Regular insulin IV infusion
  • Replace potassium (K⁺)
  • Insulin titrated more slowly
  • Treat the precipitating illness
Patient teaching

DKA

  • Never stop insulin
  • Follow sick-day rules
  • Check ketones when ill or glucose > 240

HHS

  • Stay hydrated during illness
  • Monitor glucose during illness
  • Maintain medication adherence
  • Infection is a common trigger
Red flags — escalate

DKA

  • Avoid rapid glucose correction
  • Hypokalemia as insulin shifts K⁺ into cells

HHS

  • Hypovolemic shock from severe dehydration
  • Hyperviscosity raises clot risk
Complications

DKA

  • Mortality ~1–5%
  • Cerebral edema (pediatric DKA)

HHS

  • Mortality ~10–20% (higher)
  • Venous thromboembolism (VTE)

★ marks the fact that sets a column apart.

Clinical Pearl

Ketones + Kussmaul + acidosis = DKA; extreme glucose + altered LOC + no ketones = HHS.

Component Topics

Diabetic Ketoacidosis — DKAHyperglycemic Hyperosmolar State — HHS

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