How should I initially manage an adult with diabetic ketoacidosis (blood glucose >250 mg/dL, normal serum sodium) regarding fluid therapy, insulin dosing, potassium replacement, and transition to dextrose‑containing fluids?

Management of Diabetic Ketoacidosis in Adults

Begin aggressive isotonic saline resuscitation at 15–20 mL/kg/hour in the first hour, confirm serum potassium ≥3.3 mEq/L before starting continuous IV regular insulin at 0.1 units/kg/hour, add dextrose-containing fluids when glucose falls to 250 mg/dL while maintaining insulin infusion, and administer basal subcutaneous insulin 2–4 hours before stopping the IV drip. 1

Initial Fluid Resuscitation

• Start with isotonic saline (0.9% NaCl) at 15–20 mL/kg/hour (approximately 1–1.5 L) during the first hour to restore intravascular volume and renal perfusion, regardless of the patient's corrected sodium level. 1, 2

• After the first hour, calculate corrected serum sodium by adding 1.6 mEq/L for each 100 mg/dL glucose above 100 mg/dL. 1, 2

• If corrected sodium is normal or elevated, switch to 0.45% NaCl at 4–14 mL/kg/hour. 1, 2

• If corrected sodium is low, continue 0.9% NaCl at 4–14 mL/kg/hour. 1, 2

• The typical total body water deficit in DKA is 6–9 L; aim to replace this over 24 hours while limiting the change in serum osmolality to ≤3 mOsm/kg/hour to reduce cerebral edema risk. 1, 2

Potassium Management (Critical Safety Step)

This is the single most important safety check before insulin—failure to correct severe hypokalemia can cause fatal cardiac arrhythmias. 1, 2

• If serum K⁺ <3.3 mEq/L: Hold all insulin and aggressively replace potassium at 20–40 mEq/hour until K⁺ ≥3.3 mEq/L. Obtain an ECG to assess for cardiac effects. Do not start insulin under any circumstances until this threshold is reached. 1, 2, 3

• If K⁺ 3.3–5.5 mEq/L: Insulin may be started safely. Add 20–30 mEq/L potassium to each liter of IV fluid (use approximately 2/3 potassium chloride and 1/3 potassium phosphate) once adequate urine output (≥0.5 mL/kg/hour) is confirmed. 1, 2, 3

• If K⁺ >5.5 mEq/L: Start insulin immediately without adding potassium to initial fluids. Monitor potassium every 2–4 hours as levels will fall rapidly with insulin therapy; begin supplementation once K⁺ drops below 5.5 mEq/L. 1, 2

• Target serum potassium of 4.0–5.0 mEq/L throughout treatment, not merely >3.5 mEq/L. Total body potassium depletion in DKA averages 3–5 mEq/kg even when initial levels appear normal or elevated. 1, 2

Insulin Therapy

• Confirm serum potassium ≥3.3 mEq/L before initiating any insulin. 1, 2

• Give an IV bolus of 0.1–0.15 units/kg regular insulin, then start continuous infusion at 0.1 units/kg/hour. 1, 2

• Target a glucose decline of 50–75 mg/dL per hour. 1, 2

• If glucose does not fall by at least 50 mg/dL in the first hour despite adequate hydration, double the insulin infusion rate each subsequent hour until a steady decline is achieved. 1, 2

• Continue insulin infusion until complete DKA resolution (pH >7.3, bicarbonate ≥18 mEq/L, anion gap ≤12 mEq/L, glucose <200 mg/dL) regardless of glucose normalization—ketone clearance lags behind glucose correction. 1, 2, 4

Transition to Dextrose-Containing Fluids

This is the most common error leading to recurrent ketoacidosis—never stop insulin when glucose normalizes. 1, 4

• When plasma glucose falls to 250 mg/dL, change IV fluids to 5% dextrose with 0.45–0.75% NaCl while maintaining the same insulin infusion rate. 1, 2, 3

• This allows continued insulin-mediated ketone clearance while preventing hypoglycemia. Insulin alone cannot clear ketones without adequate carbohydrate substrate. 1, 2

• Target glucose range of 150–200 mg/dL until all DKA resolution criteria are met. 1

Monitoring During Treatment

• Draw blood every 2–4 hours for serum electrolytes (especially potassium), glucose, BUN, creatinine, calculated osmolality, and venous pH. 1, 2, 3

• Use venous pH for ongoing monitoring—it is typically 0.03 units lower than arterial pH and eliminates the need for repeated arterial sticks after initial diagnosis. 1, 3

• Measure β-hydroxybutyrate in blood as the preferred method for monitoring ketosis resolution. Nitroprusside-based urine or serum ketone tests miss the predominant ketone body (β-hydroxybutyrate) and can falsely suggest worsening ketosis during treatment as β-hydroxybutyrate converts to acetoacetate. 1, 3

Transition to Subcutaneous Insulin

This is the second most common error—stopping IV insulin without adequate basal coverage causes rebound DKA. 1, 2, 4

• Administer basal subcutaneous insulin (glargine, detemir, or NPH) 2–4 hours before stopping the IV insulin infusion to ensure continuous insulin coverage and prevent rebound hyperglycemia or recurrent ketoacidosis. 1, 2, 3

• Continue the IV insulin infusion for an additional 1–2 hours after the subcutaneous basal dose to allow adequate absorption. 1, 2

• Calculate the basal dose as approximately 50% of the total 24-hour IV insulin amount given as a single daily injection; divide the remaining 50% equally among three meals as rapid-acting prandial insulin. 2

• Once the patient can eat, start a multiple-dose regimen combining short/rapid-acting and intermediate/long-acting insulin. 1, 2

Bicarbonate Administration

• Bicarbonate is NOT recommended for DKA patients with pH >6.9–7.0. Multiple studies show no benefit in acidosis resolution time or hospital length of stay, and bicarbonate may worsen ketosis, cause hypokalemia, and increase cerebral edema risk. 1, 2, 5

• Consider bicarbonate only if pH <6.9 after initial fluid resuscitation: give 100 mmol sodium bicarbonate diluted in 400 mL sterile water, infused at 200 mL/hour. 2, 3

Alternative Approach for Mild-Moderate Uncomplicated DKA

• For hemodynamically stable, alert patients with mild-moderate DKA (pH 7.25–7.30, bicarbonate 15–18 mEq/L), subcutaneous rapid-acting insulin analogs at 0.1–0.2 units/kg every 1–2 hours combined with aggressive fluid management are equally effective, safer, and more cost-effective than IV insulin. 1, 2, 3

• This approach requires adequate fluid replacement, frequent point-of-care glucose monitoring (every 1–2 hours), treatment of concurrent infections, and appropriate follow-up. 1, 2

• Continuous IV insulin remains the standard of care for critically ill, mentally obtunded, or hemodynamically unstable patients. 1, 2

Identification and Treatment of Precipitating Causes

• Obtain bacterial cultures (urine, blood, throat) if infection is suspected—infection is the most common precipitant of DKA—and start appropriate antibiotics immediately. 1, 2, 3, 5

• Actively search for other triggers: myocardial infarction, stroke, pancreatitis, insulin omission, SGLT2-inhibitor use, glucocorticoid therapy, or pregnancy. 1, 3

• Discontinue SGLT2 inhibitors immediately and do not restart until 3–4 days after metabolic stability is achieved, as these agents can precipitate euglycemic DKA. 1, 3

Common Pitfalls to Avoid

• Starting insulin before correcting severe hypokalemia (K⁺ <3.3 mEq/L) can cause life-threatening arrhythmias and cardiac arrest—this is an absolute contraindication. 1, 2, 3

• Stopping insulin when glucose falls to 250 mg/dL instead of adding dextrose and continuing insulin leads to recurrent ketoacidosis—premature insulin termination is the most common cause of DKA recurrence. 1, 4, 6

• Discontinuing IV insulin without 2–4 hour overlap of basal subcutaneous insulin causes rebound hyperglycemia and recurrent DKA. 1, 2, 4

• Inadequate potassium monitoring and replacement is a leading cause of mortality in DKA—check potassium every 2–4 hours and maintain 4.0–5.0 mEq/L. 1, 2

• Overly rapid correction of serum osmolality (>3 mOsm/kg/hour) increases the risk of cerebral edema, particularly in children but also in adults. 1, 2

• Relying on nitroprusside-based ketone tests misses β-hydroxybutyrate and delays appropriate therapy—always use direct blood β-hydroxybutyrate measurement when available. 1, 3

Special Considerations for Euglycemic DKA

• In euglycemic DKA (glucose <250 mg/dL with ketoacidosis), start 5% dextrose combined with 0.45–0.75% NaCl from the outset of insulin therapy to prevent hypoglycemia while allowing ketone clearance. 2

• Provide 150–200 g of carbohydrate per day (approximately 45–50 g every 3–4 hours) to suppress ongoing ketogenesis; use liquid carbohydrate sources (juice, broth, sports drinks) if solid foods are not tolerated. 2

• Euglycemic DKA is increasingly common with SGLT2-inhibitor use, pregnancy, starvation, or reduced oral intake—maintain high clinical suspicion in these settings. 1, 3