What are the guidelines for managing diabetic ketoacidosis (DKA) in a patient with schizophrenia, diabetic retinopathy, and glaucoma?

Management of Diabetic Ketoacidosis (DKA)

Begin with isotonic saline at 15-20 mL/kg/hour for the first hour, followed by continuous IV regular insulin at 0.1 units/kg/hour (after ensuring potassium ≥3.3 mEq/L), targeting a glucose decline of 50-75 mg/dL per hour while aggressively replacing potassium to maintain levels between 4-5 mEq/L. 1, 2

Initial Assessment and Laboratory Evaluation

Obtain the following immediately upon presentation 1, 2:

• Plasma glucose, serum ketones (β-hydroxybutyrate preferred), arterial blood gases
• Complete metabolic panel with calculated anion gap, serum osmolality
• Blood urea nitrogen, creatinine, urinalysis with urine ketones
• Complete blood count with differential, electrocardiogram
• Bacterial cultures (blood, urine, throat) if infection suspected 1, 2

Diagnostic criteria require all three: blood glucose >250 mg/dL, arterial pH <7.3 with serum bicarbonate <15 mEq/L, and presence of ketonemia or ketonuria. 2

Fluid Resuscitation Protocol

Start with isotonic saline (0.9% NaCl) at 15-20 mL/kg/hour (approximately 1-1.5 L in average adults) during the first hour to restore intravascular volume and tissue perfusion. 1, 2

After the initial hour 1, 2:

• Continue isotonic or half-normal saline based on hydration status, electrolytes, and urine output
• When glucose reaches 200-250 mg/dL, switch to 5% dextrose with 0.45-0.75% saline while continuing insulin infusion to prevent hypoglycemia and ensure complete ketoacidosis resolution 2
• Total fluid replacement should approximate 1.5 times the 24-hour maintenance requirements 1

Insulin Therapy

Critical Pre-Insulin Check

Do NOT start insulin if serum potassium is <3.3 mEq/L—this is an absolute contraindication that can cause life-threatening cardiac arrhythmias and death. 1, 2 Aggressively replace potassium first until K+ ≥3.3 mEq/L 1

Standard IV Insulin Protocol

For moderate-to-severe DKA or critically ill/mentally obtunded patients 1, 2:

• Give IV bolus of 0.1 units/kg regular insulin
• Start continuous infusion at 0.1 units/kg/hour
• Target glucose decline of 50-75 mg/dL per hour 1, 2

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

Alternative Approach for Mild-Moderate Uncomplicated DKA

For hemodynamically stable, alert patients with mild-moderate DKA, subcutaneous rapid-acting insulin analogs combined with aggressive fluid management are equally effective, safer, and more cost-effective than IV insulin. 1, 2 This requires adequate fluid replacement, frequent point-of-care glucose monitoring, and treatment of concurrent infections 2

Electrolyte Management

Potassium Replacement (Critical)

Total body potassium depletion averages 3-5 mEq/kg body weight in DKA, and insulin therapy will unmask this depletion by driving potassium intracellularly. 2

Potassium replacement protocol 1, 2:

• If K+ <3.3 mEq/L: Hold insulin, aggressively replace potassium until ≥3.3 mEq/L
• If K+ 3.3-5.5 mEq/L: Add 20-30 mEq/L potassium to IV fluids (use 2/3 KCl or potassium-acetate and 1/3 KPO₄) once adequate urine output confirmed
• If K+ >5.5 mEq/L: Withhold potassium initially but monitor closely, as levels will drop rapidly with insulin therapy
• Target serum potassium of 4-5 mEq/L throughout treatment 2
• Check potassium levels every 2-4 hours during active treatment 1, 2

Bicarbonate Administration

Bicarbonate is NOT recommended for DKA patients with pH >6.9-7.0, as multiple studies show no difference in resolution of acidosis or time to discharge, and it may worsen ketosis, cause hypokalemia, and increase cerebral edema risk. 2

Monitoring During Treatment

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

• Blood glucose (capillary or venous)
• Serum electrolytes, blood urea nitrogen, creatinine, osmolality
• Venous pH (typically 0.03 units lower than arterial pH) and anion gap
• Direct measurement of β-hydroxybutyrate in blood is the preferred method for monitoring DKA resolution (nitroprusside method only measures acetoacetic acid and acetone) 2

DKA Resolution Criteria

DKA is resolved when ALL of the following are met: glucose <200 mg/dL, serum bicarbonate ≥18 mEq/L, venous pH >7.3, and anion gap ≤12 mEq/L. 1, 2

Continue insulin infusion until complete resolution of ketoacidosis regardless of glucose levels. 2 This is a critical point—do not stop insulin just because glucose normalizes 2

Transition to Subcutaneous Insulin

Administer basal insulin (glargine or detemir) 2-4 hours BEFORE stopping the IV insulin infusion to prevent recurrence of ketoacidosis and rebound hyperglycemia—this overlap period is essential. 1, 2

Transition protocol 1, 2:

• Ensure patient can tolerate oral intake
• Start multiple-dose regimen with combination of short/rapid-acting and intermediate/long-acting insulin
• Continue IV insulin for 1-2 hours after administering subcutaneous insulin 1
• Monitor glucose every 2-4 hours during transition 1

Treatment of Precipitating Causes

Identify and treat underlying triggers concurrently with DKA management 2, 3:

• Infection (most common): urinary tract infection, pneumonia—obtain cultures and start appropriate antibiotics 1, 2
• Myocardial infarction, stroke, pancreatitis, trauma 2
• Insulin omission or inadequacy 2
• SGLT2 inhibitors: Discontinue immediately and do not restart until 3-4 days after metabolic stability is achieved 2

Special Considerations for Patients with Schizophrenia

Patients with schizophrenia require additional attention 1, 2:

• Ensure adequate monitoring compliance, as mental status may affect self-reporting of symptoms
• Consider medication interactions between antipsychotics and metabolic control
• Structured discharge planning with clear follow-up is essential 1

Common Pitfalls to Avoid

Critical errors that lead to complications or DKA recurrence 1, 2:

• Starting insulin when K+ <3.3 mEq/L—causes life-threatening arrhythmias
• Stopping IV insulin without prior basal insulin administration—most common cause of DKA recurrence
• Stopping insulin infusion when glucose normalizes but before ketoacidosis resolves
• Failing to add dextrose when glucose falls below 250 mg/dL while continuing insulin
• Inadequate potassium monitoring and replacement—leading cause of mortality in DKA 2
• Overly rapid correction of osmolality—increases cerebral edema risk, particularly in children 2

Discharge Planning

Before discharge, ensure 2:

• Identification of outpatient diabetes care providers
• Patient education on glucose monitoring, insulin administration, recognition of hyperglycemia/hypoglycemia
• Understanding of sick day management and when to seek medical care
• Scheduled follow-up appointments
• Adequate insulin supply and prescriptions