Hyperosmolar Hyperglycemic State (HHS)


πŸ” Definition:

HHS is a life-threatening acute complication of diabetes mellitus, characterized by:

  • Severe hyperglycemia
  • Marked hyperosmolarity
  • Dehydration
  • Minimal or absent ketoacidosis

πŸ“Œ More common in elderly patients with type 2 diabetes


🧬 Pathophysiology:

Factor

Effect

Relative insulin deficiency

Sufficient to prevent ketogenesis but insufficient to prevent hyperglycemia

Hyperglycemia

Osmotic diuresis β†’ profound dehydration

No significant lipolysis

Ketone production is minimal or absent

Plasma hyperosmolality

CNS dysfunction due to cellular dehydration



⚠️ Precipitating Factors:

Category

Examples

Infection

Pneumonia, UTI, sepsis

Drugs

Thiazides, steroids, antipsychotics

Non-compliance

Missed medications

Stress

MI, stroke, pancreatitis



πŸ§ͺ Diagnostic Criteria (ADA):

Parameter

HHS Values

Plasma glucose

>600 mg/dL

Arterial pH

>7.30

Serum bicarbonate

>18 mmol/L

Ketones

Minimal or absent

Effective serum osmolality

>320 mOsm/kg

Anion gap

Normal or mildly ↑

Mental status

Altered sensorium common



πŸ”¬ Effective Serum Osmolality:

Effective Osmolality (mOsm/kg)

=2Γ—Na⁺ (mEq/L)+Glucose (mg/dL)18


320 mOsm/kg is diagnostic of HHS


🧠 Clinical Features:

System

Manifestations

General

Weakness, polyuria, polydipsia

CNS

Confusion, lethargy, seizures, coma

CVS

Hypotension, tachycardia, signs of hypovolemia

Renal

Oliguria due to volume depletion



πŸ›Œ Management of HHS:

βœ… 1. Fluid Resuscitation

  • Start with 0.9% NS, 15–20 mL/kg in first hour (~1 L)
  • Switch to 0.45% NS based on corrected sodium and osmolality
  • When glucose <250 mg/dL β†’ add 5% dextrose
  • Total fluid deficit = 8–12 L (more than DKA)


βœ… 2. Insulin Therapy

  • Start only after fluids are started
  • IV insulin:
    • Bolus: 0.1 U/kg (optional)
    • Infusion: 0.05–0.1 U/kg/hr
  • Goal: ↓ glucose by 50–70 mg/dL/hr


βœ… 3. Electrolyte Correction (esp. K⁺)

  • Serum K⁺ may appear normal or high, but total body K⁺ is depleted
  • Replace based on levels:

Serum K⁺

Action

<3.3 mEq/L

Hold insulin, replace K⁺ first

3.3–5.3 mEq/L

Give K⁺ 20–30 mEq/L of fluid

>5.3 mEq/L

Monitor without replacing



βœ… 4. Monitor and Support

  • Monitor glucose, electrolytes, osmolality, ABG every 2–4 hrs
  • Watch for cerebral edema (especially if glucose drops too fast)
  • Start prophylactic LMWH due to hypercoagulable state


🧾 Criteria for Resolution of HHS:

Parameter

Target

Glucose

<250 mg/dL

Mental status

Improved

Osmolality

<300 mOsm/kg

Vital signs

Stable

Electrolytes/ABG

Normalized



⚠️ Complications:

Complication

Risk Factors

Cerebral edema

Rapid glucose/osm drop

Thrombosis

Hyperviscosity, immobility

ARDS

Severe dehydration, infection

Renal failure

Prerenal due to volume loss



πŸ”‘ Summary Mnemonic – β€œHIGH OSM” for HHS

  • H – Hyperglycemia (>600)
  • I – Insidious onset
  • G – Glucose management
  • H – Hypovolemia (fluids!)
  • O – Osmolality ↑↑
  • S – Seizures/mental status change
  • M – Minimal ketones



πŸ”„ DKA vs HHS: Comparison Table

Feature

DKA

HHS

Underlying Diabetes

Type 1 (mostly)

Type 2 (mostly)

Onset

Rapid (hours to 1–2 days)

Insidious (several days to weeks)

Plasma Glucose

>250 mg/dL

>600 mg/dL

Serum Osmolality

Mild–moderate ↑

>320 mOsm/kg

pH

<7.30

>7.30

Serum Bicarbonate

<18 mmol/L

>18 mmol/L

Anion Gap

Elevated (>12)

Normal or mildly ↑

Ketones (urine/serum)

Present (Ξ²-hydroxybutyrate ↑)

Minimal or absent

Acidosis

High anion gap metabolic acidosis

No significant acidosis

Mental Status

Alert to comatose (depends on severity)

Altered sensorium common, seizures possible

Volume Depletion

Moderate (~6 L deficit)

Severe (~8–12 L deficit)

Typical Age Group

Younger (children, adolescents)

Older adults (often >60 years)

Mortality

~2–5%

10–20% (higher)

Treatment Priorities

Fluids β†’ Insulin β†’ Electrolytes

Fluids β†’ Electrolytes β†’ Insulin

Risk of Cerebral Edema

Higher in children

Rare, but possible if glucose ↓ too rapidly



πŸ’‘ Key Differences:

  • HHS has much higher glucose and osmolality, but minimal acidosis.
  • DKA has marked acidosis and ketosis, but glucose is modestly elevated compared to HHS.