What is the appropriate management for a 65-year-old patient with a history of type 2 diabetes mellitus presenting with severe hyperglycemia and likely Hyperosmolar Hyperglycemic State?

Management of Hyperosmolar Hyperglycemic State in a 65-Year-Old with Type 2 Diabetes

Immediately initiate aggressive fluid resuscitation with 0.9% isotonic saline at 15-20 mL/kg/hour for the first hour, followed by insulin therapy only after confirming adequate potassium levels and once osmolality stops declining with fluids alone. 1, 2

Initial Assessment and Diagnostic Confirmation

Obtain the following laboratory studies immediately to confirm HHS diagnosis and guide management 1, 2:

• Plasma glucose (expect ≥600 mg/dL in HHS)
• Serum osmolality (diagnostic threshold ≥320 mOsm/kg, calculated as 2×[Na+] + glucose/18 + BUN/2.8)
• Arterial blood gas (pH should be >7.3, bicarbonate ≥15 mEq/L)
• Serum ketones (should be minimal: ≤3.0 mmol/L)
• Complete metabolic panel with particular attention to sodium, potassium, and creatinine
• Electrocardiogram to assess for cardiac effects and precipitating causes 1, 2

The corrected sodium must be calculated by adding 1.6 mEq/L for every 100 mg/dL of glucose above 100 mg/dL 1.

Phase 1: Fluid Resuscitation (First Hour)

Begin with 0.9% isotonic saline at 15-20 mL/kg/hour (approximately 1-1.5 liters in the first hour for a 70 kg patient) 1, 2. This is the absolute priority as fluid losses in HHS typically range from 100-220 mL/kg 3.

The goal is to restore intravascular volume and tissue perfusion before addressing hyperglycemia 1, 4. In elderly patients or those with cardiac/renal compromise, monitor closely for fluid overload with frequent assessment of cardiac, renal, and mental status 1.

Critical Potassium Management Before Insulin

Do not start insulin if serum potassium is <3.3 mEq/L 2. This is an absolute contraindication as insulin drives potassium intracellularly and can precipitate life-threatening cardiac arrhythmias and death 1, 2, 5.

If potassium is <3.3 mEq/L 2:

• Continue isotonic saline while holding insulin
• Add 20-40 mEq/L potassium to IV fluids (use 2/3 KCl or potassium-acetate and 1/3 KPO4) 1, 2
• Obtain electrocardiogram to assess cardiac effects 2
• Aggressively replete potassium until ≥3.3 mEq/L before starting insulin

Once potassium is ≥3.3 mEq/L, add 20-40 mEq/L potassium to all subsequent IV fluids 1, 2.

Insulin Therapy Timing and Protocol

A critical distinction in HHS management: delay insulin therapy until osmolality stops declining with fluid replacement alone, unless significant ketonemia is present 2, 3. This differs from DKA where insulin is started immediately.

When insulin is indicated 1, 2:

• IV bolus: 0.1 units/kg regular insulin (approximately 7-10 units for a 70 kg patient)
• Continuous infusion: 0.1 units/kg/hour (5-7 units/hour)
• Target glucose decline: 50-75 mg/dL per hour

If glucose does not fall by 50 mg/dL in the first hour, verify adequate hydration status, then double the insulin infusion rate every hour until achieving steady decline of 50-75 mg/dL/hour 1, 2.

Transition to Hypotonic Fluids

After the initial hour and once hemodynamic stability is achieved, switch to 0.45% saline to address the hyperosmolar state more effectively 1, 4. The rate should be adjusted to replace estimated fluid deficits within 24 hours 1.

The osmolality decline must not exceed 3 mOsm/kg/hour to minimize risk of cerebral edema and osmotic demyelination syndrome 1, 3. This is a critical safety parameter requiring monitoring every 2-4 hours.

Glucose Management During Treatment

When plasma glucose reaches 250-300 mg/dL 1, 4:

• Add 5% dextrose to IV fluids
• Reduce insulin infusion to 0.05-0.1 units/kg/hour (3-6 units/hour)
• Target glucose of 10-15 mmol/L (180-270 mg/dL) in the first 24 hours 3

This prevents hypoglycemia while allowing continued insulin administration to resolve the hyperosmolar state 1.

Monitoring Requirements

Check the following every 2-4 hours 1, 2:

• Blood glucose (bedside and laboratory confirmation)
• Serum electrolytes (sodium, potassium, chloride, bicarbonate)
• Calculated serum osmolality
• Venous pH (arterial blood gases are generally unnecessary after initial assessment)
• Blood urea nitrogen and creatinine
• Mental status assessment

Resolution Criteria for HHS

HHS is considered resolved when all of the following criteria are met 3:

• Serum osmolality <300 mOsm/kg
• Blood glucose <15 mmol/L (270 mg/dL)
• Patient's cognitive status returned to baseline
• Hypovolaemia corrected (urine output ≥0.5 mL/kg/hour)

Transition to Subcutaneous Insulin

Administer basal insulin (glargine or detemir) subcutaneously 2-4 hours BEFORE discontinuing the IV insulin infusion 1, 6, 2. This is the most common error leading to recurrence of hyperglycemic crisis 2.

The transition protocol 1, 6, 2:

• Ensure patient can tolerate oral intake
• Give long-acting basal insulin subcutaneously
• Continue IV insulin for 2-4 hours after subcutaneous dose
• Initiate multiple-dose regimen with combination of rapid-acting and long-acting insulin
• Continue glucose monitoring every 2-4 hours during transition

Common Pitfalls to Avoid

Starting insulin too early: In HHS without significant ketosis, premature insulin administration before adequate fluid resuscitation can worsen hyperosmolality and precipitate vascular collapse 3.

Correcting osmolality too rapidly: Decline >3 mOsm/kg/hour increases risk of cerebral edema and osmotic demyelination syndrome, which can be fatal 1, 3.

Stopping IV insulin without prior basal insulin: This consistently leads to rebound hyperglycemia and potential recurrence of HHS 1, 6, 2.

Inadequate potassium monitoring: Insulin therapy drives potassium intracellularly; failure to monitor and replace potassium can result in life-threatening hypokalemia, respiratory paralysis, and cardiac arrhythmias 1, 5.

Fluid overload in elderly patients: Given typical fluid deficits of 100-220 mL/kg, elderly patients with cardiac or renal disease require particularly careful monitoring to avoid iatrogenic pulmonary edema 1, 3.

Identifying and Treating Precipitating Causes

Simultaneously investigate and treat underlying triggers 1, 2, 4:

• Infections (most common): obtain cultures of blood, urine, and other sites as indicated; start empiric antibiotics if infection suspected
• Cardiovascular events: myocardial infarction, stroke (common precipitants in elderly)
• Medications: review for recent addition of diuretics, corticosteroids, beta-blockers, phenytoin, SGLT2 inhibitors
• Non-adherence: inadequate fluid intake during illness, missed medications

The high mortality associated with HHS (historically 10-20%) is largely attributable to precipitating illnesses rather than the metabolic derangement itself 4, 7.

Disposition and Ongoing Care

All patients with HHS require intensive care unit admission for continuous monitoring during the acute phase 1, 2, 7. The critically ill nature of these patients, combined with the need for frequent laboratory monitoring and potential for rapid deterioration, mandates this level of care.

Many patients presenting with HHS will not require long-term insulin therapy after recovery and can be managed with oral agents or diet modification, particularly if this represents their first presentation of type 2 diabetes 4.