What is the most appropriate initial management for a patient with diabetic ketoacidosis (DKA), severe hyperglycemia, and metabolic acidosis, with a blood glucose level of hyperglycemia, a pH indicating acidosis, and a bicarbonate level of 15 mEq/L?

Initial Management of Diabetic Ketoacidosis

The most appropriate initial management is C: IV fluids and regular insulin. This patient meets diagnostic criteria for moderate DKA (glucose 380 mg/dL, pH 7.15, bicarbonate 15 mEq/L), and the American Diabetes Association guidelines unequivocally recommend beginning with aggressive isotonic saline resuscitation at 15-20 mL/kg/hour for the first hour, followed by continuous IV regular insulin infusion at 0.1 units/kg/hour after confirming adequate potassium levels. 1, 2

Why IV Fluids Come First

• Fluid resuscitation is the absolute first priority because DKA causes total body water deficits of 6-9 liters, and restoring circulatory volume is essential before insulin therapy can be effective. 2
• The American Diabetes Association recommends isotonic (0.9%) saline at 15-20 mL/kg/hour for the first hour to restore tissue perfusion and begin correcting the severe dehydration. 1, 2
• Total fluid replacement should approximate 1.5 times the 24-hour maintenance requirements over 24 hours. 1

Why Regular IV Insulin (Not Subcutaneous)

• Continuous IV regular insulin infusion is the preferred treatment method for moderate to severe DKA, not subcutaneous insulin. 1
• Start with an IV bolus of 0.1 units/kg followed by continuous infusion at 0.1 units/kg/hour, targeting a glucose decline of 50-75 mg/dL per hour. 1
• Subcutaneous insulin is only appropriate for mild, uncomplicated DKA in hemodynamically stable, alert patients—this patient's pH of 7.15 indicates moderate DKA requiring IV therapy. 1

Critical Potassium Checkpoint Before Insulin

• 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
• Once potassium is ≥3.3 mEq/L and renal function is confirmed, add 20-30 mEq/L potassium to IV fluids (using 2/3 KCl and 1/3 KPO4). 1, 2
• Insulin drives potassium intracellularly, causing rapid decline despite total body potassium depletion of 3-5 mEq/kg. 2

Why NOT Bicarbonate (Option A)

• Bicarbonate therapy is not recommended for DKA management except in extreme cases where pH <6.9. 2
• This patient's pH of 7.15 is well above this threshold, and bicarbonate administration can worsen ketosis, cause hypokalemia, and increase the risk of cerebral edema. 3
• The acidosis will resolve with appropriate fluid and insulin therapy alone. 1

Monitoring During Treatment

• Check blood glucose every 2-4 hours and measure serum electrolytes, glucose, BUN, creatinine, osmolality, and venous pH every 2-4 hours. 1
• When glucose falls below 200-250 mg/dL, add dextrose to IV fluids while continuing insulin infusion to clear ketones and prevent hypoglycemia. 2
• Direct measurement of β-hydroxybutyrate in blood is preferred over urine ketones for monitoring DKA resolution. 1, 4

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, 4
• Only after complete resolution should you transition to subcutaneous insulin, administering basal insulin (glargine or detemir) 2-4 hours before stopping the IV insulin infusion to prevent DKA recurrence. 1

Common Pitfall to Avoid

• Never discontinue IV insulin when glucose normalizes—ketoacidosis takes longer to resolve than hyperglycemia, and premature insulin cessation causes DKA recurrence. 2
• The most common error is stopping IV insulin without prior basal insulin administration. 1