What is the recommended management of diabetic ketoacidosis (DKA) in an adult patient without contraindications, including fluid resuscitation, insulin therapy, electrolyte replacement, monitoring, and transition to subcutaneous insulin?

Management of Diabetic Ketoacidosis in Adults

Begin immediate fluid resuscitation 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 once serum potassium reaches ≥3.3 mEq/L, while adding 20–30 mEq potassium per liter of IV fluid and monitoring glucose, electrolytes, and pH every 2–4 hours until complete resolution. 1

Initial Assessment & Laboratory Workup

Obtain the following stat laboratory studies on presentation: 1, 2

• Plasma glucose, arterial or venous pH, serum electrolytes with calculated anion gap
• Serum ketones (β-hydroxybutyrate preferred over nitroprusside methods)
• Blood urea nitrogen, creatinine, calculated effective serum osmolality
• Urinalysis with urine ketones, complete blood count with differential
• Electrocardiogram

Obtain bacterial cultures (blood, urine, throat) and chest X-ray only when infection is clinically suspected, as infection is the most common precipitating factor. 1, 2

DKA is diagnosed when all of the following criteria are met: glucose >250 mg/dL, arterial pH <7.3, serum bicarbonate <15 mEq/L, moderate-to-large ketonuria/ketonemia, and anion gap >12 mEq/L. 2

Fluid Resuscitation Protocol

First Hour

Administer isotonic saline (0.9% NaCl) at 15–20 mL/kg/hour (approximately 1–1.5 L in an average adult) to restore intravascular volume and renal perfusion. 1, 2, 3

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

When 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 to prevent hypoglycemia and ensure complete ketoacidosis resolution. 1, 2, 3

The typical total body water deficit in DKA is 6–9 L, which should be replaced over 24 hours while limiting the change in serum osmolality to ≤3 mOsm/kg/hour to reduce cerebral edema risk. 1

Critical Potassium Management (Class A Evidence)

Total body potassium depletion is universal in DKA, averaging 3–5 mEq/kg body weight, even when serum potassium appears normal or elevated initially. 1, 2

Potassium-Based Insulin Decision Algorithm

If serum K⁺ <3.3 mEq/L: 1, 2, 3

• Do not start insulin under any circumstances—this is an absolute contraindication
• Continue isotonic saline at 15–20 mL/kg/hour
• Confirm adequate urine output (≥0.5 mL/kg/hour)
• Aggressively replace potassium at 20–40 mEq/hour until K⁺ ≥3.3 mEq/L
• Obtain electrocardiogram to assess for cardiac effects of hypokalemia
• This threshold carries Class A evidence (high-quality randomized trials)

If serum K⁺ 3.3–5.5 mEq/L: 1, 2, 3

• Insulin may be started safely
• Add 20–30 mEq potassium per liter of IV fluid once adequate urine output is confirmed
• Use a mixture of approximately 2/3 potassium chloride (or potassium acetate) and 1/3 potassium phosphate

If serum K⁺ >5.5 mEq/L: 1, 2

• Start insulin immediately without potassium supplementation
• Monitor potassium every 2–4 hours as levels will fall rapidly with insulin therapy
• Add potassium replacement once the level falls below 5.5 mEq/L

Target serum potassium throughout treatment: 4.0–5.0 mEq/L. 1, 2

Insulin Therapy Protocol

Preparation & Initiation

Prepare a standardized solution of 100 units regular human insulin in 100 mL of 0.9% sodium chloride (1 U/mL) to minimize dosing errors. 1

Prime the infusion tubing with 20 mL of the prepared solution before connecting to the patient to prevent insulin adsorption to tubing walls. 1

Confirm serum potassium ≥3.3 mEq/L before initiating insulin. 1, 2, 3

Standard Dosing for Moderate-to-Severe DKA

Give an IV bolus of regular insulin 0.1 units/kg, followed immediately by a continuous infusion of 0.1 units/kg/hour. 1, 2, 3

Only regular (short-acting) insulin may be used intravenously; rapid-acting analogs must never be administered IV. 1

Target Glucose Decline & Titration

Aim for a glucose decline of 50–75 mg/dL per hour. 1, 2, 3

If glucose does not fall by ≥50 mg/dL in the first hour: 1, 2

• Verify adequate hydration status
• If hydration is acceptable, double the insulin infusion rate every hour until a steady decline of 50–75 mg/dL/hour is achieved

Critical Principle: Never Stop Insulin When Glucose Falls

Continue the insulin infusion until complete DKA resolution regardless of glucose level. 1, 2 When glucose reaches approximately 250 mg/dL, add dextrose to the IV fluids while maintaining the insulin infusion at the same rate to continue clearing ketones. 1, 2, 3

Stopping insulin when glucose normalizes is the most common error leading to persistent or recurrent ketoacidosis. 2, 4

Monitoring During Treatment

Check the following parameters every 2–4 hours until the patient is metabolically stable: 1, 2, 3

• Blood glucose (bedside)
• Serum electrolytes (especially potassium)
• Venous pH (typically 0.03 units lower than arterial pH; repeat arterial gases are generally unnecessary)
• Serum bicarbonate and calculated anion gap
• Blood urea nitrogen, creatinine, calculated osmolality

Use direct measurement of β-hydroxybutyrate in blood for monitoring ketone clearance. 1, 2 Nitroprusside-based urine or serum ketone tests detect only acetoacetate and acetone, missing the predominant ketone body (β-hydroxybutyrate), and may delay appropriate therapy. 1, 2

DKA Resolution Criteria

DKA is resolved when all of the following criteria are met simultaneously: 1, 2, 3

• Glucose <200 mg/dL
• Serum bicarbonate ≥18 mEq/L
• Venous pH >7.3
• Anion gap ≤12 mEq/L

Ketonemia resolves more slowly than hyperglycemia; therefore, insulin must not be stopped prematurely based on glucose alone. 1

Transition to Subcutaneous Insulin

Critical Timing to Prevent Recurrence

Administer a long-acting basal insulin (glargine or detemir) subcutaneously 2–4 hours BEFORE stopping the IV insulin infusion. 1, 2, 3 This overlap is essential to prevent rebound hyperglycemia and recurrent DKA—failure to overlap is the single most common cause of DKA recurrence. 1, 4

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

Dosing the Subcutaneous Regimen

Use approximately 50% of the total 24-hour IV insulin dose as a single daily dose of long-acting basal insulin. 1

Divide the remaining 50% of the 24-hour IV insulin dose equally among three meals as rapid-acting prandial insulin. 1

For newly diagnosed patients, estimate total daily insulin requirement at 0.5–1.0 units/kg/day. 2, 3

Alternative Approach for Mild-to-Moderate Uncomplicated DKA

For hemodynamically stable, alert patients with mild-to-moderate DKA, subcutaneous rapid-acting insulin analogs (0.1–0.2 units/kg every 1–2 hours) combined with aggressive IV fluid management are equally effective, safer, and more cost-effective than continuous IV insulin. 1, 2 This approach requires adequate fluid replacement, frequent bedside glucose monitoring, and treatment of concurrent infections. 1, 2

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

Identification & Treatment of Precipitating Causes

Identify and treat the underlying precipitating factor concurrently with metabolic correction: 1, 2, 3

• Infection (most common): Obtain cultures and start appropriate antibiotics promptly
• Myocardial infarction, cerebrovascular accident, pancreatitis, trauma
• Insulin omission or inadequacy
• SGLT2 inhibitor use: Discontinue immediately and do not restart until 3–4 days after metabolic stability is achieved 1, 2
• Glucocorticoid therapy, pregnancy, alcohol abuse

Bicarbonate Administration: Generally Not Recommended

Bicarbonate is NOT recommended for DKA patients with pH >6.9–7.0. 1, 2 Multiple studies show no difference in resolution of acidosis or time to discharge with bicarbonate use, and it may worsen ketosis, cause hypokalemia, and increase cerebral edema risk. 1, 2

Consider bicarbonate only if pH <6.9: Administer 100 mEq sodium bicarbonate diluted in 400 mL sterile water, infused at 200 mL/hour. 2

Common Pitfalls & How to Avoid Them

1. Starting insulin before correcting severe hypokalemia (K⁺ <3.3 mEq/L): This can cause life-threatening cardiac arrhythmias, cardiac arrest, and respiratory muscle weakness. 1, 2, 3 Always confirm K⁺ ≥3.3 mEq/L before any insulin administration.

2. Stopping IV insulin when glucose falls to 250 mg/dL: This leads to persistent or recurrent ketoacidosis. 2, 4 Instead, add dextrose to IV fluids and continue insulin at the same rate until all resolution criteria are met.

3. Discontinuing IV insulin without prior basal insulin overlap: This is the most common cause of DKA recurrence. 1, 4 Always give basal insulin 2–4 hours before stopping the IV infusion.

4. Using nitroprusside-based ketone tests for monitoring: These miss β-hydroxybutyrate and may delay appropriate therapy. 1, 2 Use direct blood β-hydroxybutyrate measurement when available.

5. Inadequate potassium monitoring and replacement: Hypokalemia is a leading cause of mortality in DKA. 2 Check potassium every 2–4 hours and maintain levels at 4.0–5.0 mEq/L throughout treatment.

6. Correcting serum osmolality faster than 3 mOsm/kg/hour: This increases the risk of cerebral edema, particularly in children and adolescents. 1, 2

Special Considerations

Euglycemic DKA

In patients presenting with glucose <200–250 mg/dL but meeting other DKA criteria (often due to SGLT2 inhibitors, pregnancy, or starvation ketosis with vomiting), initiate dextrose-containing IV fluids (D5W with 0.45–0.75% NaCl) simultaneously with insulin infusion to prevent hypoglycemia while clearing ketones. 1

Provide an estimated 150–200 g of carbohydrate per day to suppress ongoing ketogenesis. 1

Patients with Cardiac or Renal Impairment

Monitor closely for fluid overload during aggressive fluid resuscitation. 1 If anuric or oliguric, potassium repletion must be more cautious with nephrology consultation. 1