What is the treatment approach for an older adult patient with type 2 diabetes and Hyperosmolar Hyperglycemic State (HHS)?

Treatment of Hyperosmolar Hyperglycemic State (HHS) in Older Adults with Type 2 Diabetes

Aggressive intravenous fluid resuscitation with 0.9% sodium chloride is the cornerstone of HHS treatment and takes absolute priority over insulin therapy, which should be withheld until fluid replacement alone stops lowering blood glucose or unless significant ketonaemia is present. 1, 2

Immediate Assessment and Monitoring (0-60 minutes)

Confirm the diagnosis by documenting:

• Serum osmolality ≥320 mOsm/kg (calculated as [2×Na+] + glucose + urea) 1
• Marked hyperglycemia ≥30 mmol/L (≥540 mg/dL) 1
• Absence of significant ketosis (ketones ≤3.0 mmol/L) and acidosis (pH >7.3, bicarbonate ≥15 mmol/L) 1
• Profound dehydration with fluid losses typically 100-220 mL/kg body weight 1

Establish intensive monitoring including:

• Hourly capillary blood glucose initially 1
• Serum osmolality measurements every 1-2 hours to track response (aim for reduction of 3-8 mOsm/kg/h) 1, 2
• Continuous cardiac monitoring and hourly vital signs given high risk of myocardial infarction and stroke 2
• Hourly urine output monitoring (target ≥0.5 mL/kg/h once established) 1

Identify precipitating causes immediately, as underlying infections (pneumonia, urinary tract infections) are the most common triggers and must be treated concurrently 3, 4. Other precipitants include gastrointestinal hemorrhage, cardiovascular events, and medications (thiazides, steroids, phenytoin) 3, 5.

Fluid Resuscitation Strategy (First Priority)

Administer 0.9% sodium chloride as the principal resuscitation fluid to restore circulating volume and reverse dehydration 1, 2. The typical adult requires an average of 9 liters over 48 hours, though elderly patients require careful monitoring for fluid overload 4.

Initial fluid administration protocol:

• Give 0.9% NaCl rapidly until vital signs stabilize and adequate organ perfusion is restored 5
• An initial rise in sodium level is expected and normal—this is NOT an indication to switch to hypotonic fluids 2
• Once hemodynamically stable, some protocols suggest transitioning to 0.45% NaCl, though this remains controversial 5
• Critical pitfall: In elderly patients with congestive heart failure or cerebral stroke, aggressive fluid replacement must be balanced against risks of fluid overload and cerebral edema 3

Insulin Administration (Delayed Until Appropriate)

Withhold insulin initially because fluid replacement alone will cause blood glucose to fall, and premature insulin use may be detrimental 1, 2.

Initiate insulin only when:

• Blood glucose stops falling with IV fluids alone, OR
• Significant ketonaemia is present (>3.0 mmol/L) 1, 2

Insulin dosing protocol when indicated:

• Give 10-15 units regular human insulin as IV bolus (or 0.1 units/kg) 5, 4
• Follow with continuous infusion at 0.1 units/kg/hour 5, 4
• Target blood glucose of 10-15 mmol/L (180-270 mg/dL) in the first 24 hours—do NOT aim for normoglycemia 1
• Once glucose reaches 13.9-16.7 mmol/L (250-300 mg/dL), add 5% or 10% dextrose to IV fluids and reduce insulin infusion rate 5, 1

Electrolyte Management

Potassium replacement is critical despite often normal or elevated initial levels, as total body potassium is severely depleted 5, 4.

Potassium protocol:

• Do NOT start potassium replacement until urine output is established 5
• Once urine output confirmed, replace potassium according to serum levels to maintain 4-5 mEq/L 5
• Monitor potassium levels every 2-4 hours initially given high risk of life-threatening hypokalemia with treatment 6

Special Considerations for Older Adults

Elderly patients face substantially higher mortality from HHS, with age being the single best prognostic indicator 3. Contributing factors include:

• Reduced glomerular filtration rate and elevated renal threshold for glucose 3
• Impaired thirst mechanism inappropriate to hydration status 3
• Frequent comorbidities (heart failure, renal dysfunction) that complicate aggressive fluid resuscitation 3

In critically ill and mentally obtunded older patients with HHS, continuous intravenous insulin remains the standard of care once fluid resuscitation criteria are met 6.

Treatment Goals and Resolution Criteria

Aim for gradual correction to prevent neurological complications:

• Osmolality reduction of 3-8 mOsm/kg/hour (rapid changes risk central pontine myelinolysis) 1, 2
• Blood glucose 10-15 mmol/L (180-270 mg/dL) in first 24 hours 1
• Avoid hypoglycemia and hypokalaemia 1

HHS is resolved when:

• Osmolality <300 mOsm/kg 1
• Hypovolemia corrected (urine output ≥0.5 mL/kg/h) 1
• Cognitive status returned to baseline 1
• Blood glucose <15 mmol/L (270 mg/dL) 1

Prevention of Complications

Implement thromboprophylaxis immediately given extremely high risk of venous thromboembolism in HHS 1.

Monitor for and prevent:

• Cerebral edema (especially if osmolality corrected too rapidly) 2
• Myocardial infarction and stroke (common precipitants and complications) 2
• Foot ulceration in immobilized elderly patients 1
• Osmotic demyelination syndrome from overly rapid osmolality correction 1, 2

Post-Resolution Management

Many older adults with HHS will not require long-term insulin therapy after recovery and can be managed with diet or oral agents, as HHS typically occurs in type 2 diabetes with residual beta-cell function 5.

Structured discharge planning should begin at admission and include identification of precipitating causes, medication reconciliation, and diabetes self-management education to prevent recurrence 6.