What is the recommended management of diabetic ketoacidosis in an adult with presumed type 1 diabetes?

Management of Diabetic Ketoacidosis in Adults

Begin with aggressive isotonic saline resuscitation at 15–20 mL/kg/hour in the first hour, followed by continuous IV regular insulin at 0.1 units/kg/hour once serum potassium is ≥3.3 mEq/L, while adding dextrose-containing fluids when glucose falls to 250 mg/dL and continuing insulin until complete resolution of ketoacidosis (pH >7.3, bicarbonate ≥18 mEq/L, anion gap ≤12 mEq/L). 1, 2, 3

Initial Diagnostic Assessment

Obtain venous blood gases, comprehensive metabolic panel with calculated anion gap, direct measurement of β-hydroxybutyrate (not nitroprusside-based ketone tests), complete blood count, urinalysis, and electrocardiogram immediately. 1, 3 If infection is suspected—the most common precipitating factor—obtain blood, urine, and throat cultures and initiate appropriate antibiotics without delay. 1, 2, 3

Diagnostic criteria require all three: glucose >250 mg/dL, venous pH <7.3, and serum bicarbonate <15 mEq/L with moderate-to-large ketonemia or ketonuria. 1, 3 Calculate the anion gap using [Na⁺] - ([Cl⁻] + [HCO₃⁻]); it should exceed 10–12 mEq/L in DKA. 3

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, 3 If corrected sodium is normal or elevated, switch to 0.45% NaCl at 4–14 mL/kg/hour. 1, 2, 3 If corrected sodium is low, continue 0.9% NaCl at the same rate. 1, 2, 3

When glucose reaches 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 This is a critical step—never stop insulin when glucose normalizes; instead add dextrose. 1, 3

Aim to replace the total fluid deficit (typically 6–9 L) within 24 hours while limiting the change in serum osmolality to ≤3 mOsm/kg/hour to reduce cerebral edema risk. 1

Critical Potassium Management

This is the most important safety check before starting insulin. Total body potassium depletion is universal in DKA (≈3–5 mEq/kg) even when initial serum potassium appears normal or elevated. 1, 2, 3

If K⁺ <3.3 mEq/L: This is an absolute contraindication to insulin therapy (Class A evidence). 1, 2, 3 Hold insulin completely and aggressively replace potassium at 20–40 mEq/hour until K⁺ ≥3.3 mEq/L to prevent fatal cardiac arrhythmias, cardiac arrest, and respiratory muscle weakness. 1, 2

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 (approximately 2/3 potassium chloride or acetate and 1/3 potassium phosphate) once adequate urine output is confirmed. 1, 2, 3

If K⁺ >5.5 mEq/L: Start insulin immediately but withhold potassium supplementation initially. Monitor every 2–4 hours as levels will fall rapidly with insulin therapy, then add potassium once K⁺ drops below 5.5 mEq/L. 1, 2

Target serum potassium of 4.0–5.0 mEq/L throughout treatment. 1, 2 Inadequate potassium monitoring and replacement is a leading cause of mortality in DKA. 1

Insulin Therapy Protocol

Confirm serum potassium ≥3.3 mEq/L before initiating insulin—this cannot be overemphasized. 1, 2, 3

Start continuous IV regular insulin infusion at 0.1 units/kg/hour. 1, 2, 3 An initial IV bolus of 0.1 units/kg is optional but not required. 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 of 50–75 mg/dL per hour is achieved. 1, 2

Continue insulin infusion until complete DKA resolution regardless of glucose level. 1, 3 Premature termination of insulin therapy before complete resolution of ketosis is the most common cause of recurrent DKA. 1, 4

Monitoring During Treatment

Draw blood every 2–4 hours for serum electrolytes (especially potassium), glucose, BUN, creatinine, calculated osmolality, venous pH, bicarbonate, and anion gap. 1, 2, 3 Venous pH is typically 0.03 units lower than arterial pH and is adequate for ongoing monitoring after initial diagnosis. 1

Use direct measurement of β-hydroxybutyrate in blood as the preferred method for monitoring ketosis resolution. 1, 3 Nitroprusside-based ketone tests (urine or blood) detect only acetoacetate and acetone, missing the predominant ketone body β-hydroxybutyrate, and may delay appropriate therapy. 1

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

Do not transition to subcutaneous insulin until every single criterion is achieved. 3

Bicarbonate Administration

Do NOT administer bicarbonate for DKA patients with pH >6.9–7.0. 1, 2, 3 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

For patients with pH <6.9, consider 100 mmol sodium bicarbonate diluted in 400 mL sterile water, infused at 200 mL/hour. 2

Transition to Subcutaneous Insulin

Administer basal subcutaneous insulin (glargine, detemir, or NPH) 2–4 hours BEFORE stopping the IV insulin infusion. 1, 2, 3 This overlap is essential to prevent rebound hyperglycemia and recurrence of ketoacidosis. 1, 2, 3

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

Calculate total daily insulin dose based on the patient's pre-admission regimen or estimate 0.5–0.8 units/kg/day for newly diagnosed patients. 3 Use approximately 50% of the total 24-hour IV insulin amount as a single daily dose of long-acting insulin, and divide the remaining 50% equally among three meals as rapid-acting prandial insulin. 1

Once the patient can tolerate oral intake, start a multiple-dose schedule using a combination of short/rapid-acting and intermediate/long-acting insulin. 1, 2, 3

Alternative Approach for Mild-Moderate Uncomplicated DKA

For hemodynamically stable, alert patients with mild-to-moderate uncomplicated DKA, subcutaneous rapid-acting insulin analogs (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, and treatment of concurrent infections. 1

Continuous IV insulin remains the standard of care for moderate-to-severe DKA, critically ill patients, and mentally obtunded patients. 1, 2

Identification and Treatment of Precipitating Causes

Actively search for and treat precipitating factors concurrently with metabolic correction: 1, 3

• Infection (most common)—obtain cultures and start antibiotics
• Myocardial infarction
• Cerebrovascular accident
• Insulin omission or inadequacy
• Pancreatitis
• SGLT2 inhibitor use (discontinue immediately and do not restart until 3–4 days after metabolic stability)
• Glucocorticoid therapy
• Pregnancy

Common Pitfalls to Avoid

Critical errors that lead to complications or recurrent DKA: 1, 4

1. Starting insulin when K⁺ <3.3 mEq/L—can cause fatal arrhythmias
2. Stopping insulin when glucose falls to 250 mg/dL without adding dextrose—leads to recurrent ketoacidosis
3. Discontinuing IV insulin without 2–4 hour overlap with basal subcutaneous insulin—most common cause of DKA recurrence
4. Inadequate potassium monitoring and replacement—leading cause of mortality
5. Using nitroprusside-based ketone tests for monitoring—misses β-hydroxybutyrate and delays therapy
6. Overly rapid correction of osmolality (>3 mOsm/kg/hour)—increases cerebral edema risk

Discharge Planning

Ensure structured discharge planning including: 1, 3

• Identification of outpatient diabetes care providers
• Patient education on DKA recognition, prevention, and sick-day management
• Understanding of glucose monitoring and insulin administration
• Recognition and treatment of hyperglycemia/hypoglycemia
• Adequate outpatient insulin supply with attention to medication access and affordability
• Scheduled follow-up appointments prior to discharge