What intravenous fluid composition and dosing should be used to treat a ketotic patient (e.g., early diabetic ketoacidosis, starvation ketosis, or hypoglycemia with elevated ketones) to suppress ketogenesis while avoiding hyperglycaemia?

Dextrose-Containing IV Fluids for Ketotic Patients

For ketotic patients (DKA, starvation ketosis, or hypoglycemia with ketones), administer 5% dextrose combined with 0.45–0.75% saline plus 20–30 mEq/L potassium once plasma glucose falls to 200–250 mg/dL, while continuing insulin infusion at 0.05–0.1 U/kg/hour to clear ketones and prevent hypoglycemia. 1

Initial Fluid Resuscitation (Before Dextrose)

• Begin with isotonic saline (0.9% NaCl) at 15–20 mL/kg/hour for the first hour to restore circulatory volume and correct the typical 6–9 liter total body water deficit. 1, 2
• Continue isotonic or half-normal saline (depending on corrected sodium) at 4–14 mL/kg/hour until glucose approaches 250 mg/dL. 1

Critical Potassium Management Before Any Insulin

• Never start insulin if serum potassium is <3.3 mEq/L—this is an absolute contraindication that can cause fatal cardiac arrhythmias. 1, 2
• If K⁺ is 3.3–5.5 mEq/L, add 20–30 mEq/L potassium to each liter of IV fluid (using 2/3 KCl and 1/3 KPO₄) once adequate urine output is confirmed. 1, 2
• Target serum potassium of 4.0–5.0 mEq/L throughout treatment, checking levels every 2–4 hours. 1

Insulin Therapy Protocol

• Start continuous IV regular insulin at 0.1 U/kg/hour (without bolus) once potassium is ≥3.3 mEq/L. 1
• If glucose does not fall by 50 mg/dL in the first hour, double the insulin rate hourly until achieving a steady decline of 50–75 mg/dL per hour. 1, 2

Transition to Dextrose-Containing Fluids

When plasma glucose reaches 200–250 mg/dL, immediately switch to D5W (5% dextrose) combined with 0.45–0.75% saline while maintaining the same insulin infusion rate. 1, 2 This is the critical intervention that distinguishes proper ketone management from inadequate treatment.

Rationale for Dextrose Addition

• Insulin alone cannot clear ketones without adequate carbohydrate substrate—adults require 150–200 grams of carbohydrate daily to suppress ketogenesis, even during acute illness. 1
• The liver continues producing ketones during starvation states despite insulin administration; both insulin and glucose are necessary to resolve ketonuria. 1
• Never stop insulin when glucose normalizes—ketoacidosis takes longer to resolve than hyperglycemia, and premature insulin cessation causes DKA recurrence. 1, 2

Target Glucose Range During Ketone Clearance

• Maintain plasma glucose at 150–200 mg/dL by adjusting dextrose concentration (5–10%) while continuing insulin infusion until ketoacidosis fully resolves. 1
• Monitor blood glucose every 1–2 hours and adjust dextrose concentration as needed to prevent hypoglycemia. 1

Special Consideration: Euglycemic DKA

For euglycemic DKA (initial glucose <250 mg/dL), start D5W combined with 0.45–0.75% saline from the outset of insulin therapy to prevent hypoglycemia while clearing ketones. 1, 3, 4

• This presentation is increasingly common with SGLT2 inhibitors, pregnancy, fasting, or reduced caloric intake. 5, 3
• The same insulin infusion rate (0.1 U/kg/hour) is required despite lower glucose levels because ketone clearance depends on insulin action. 1

Monitoring Parameters

• Check blood glucose, serum electrolytes (especially potassium), venous pH, serum bicarbonate, and β-hydroxybutyrate every 2–4 hours until stable. 1, 2
• Use direct blood β-hydroxybutyrate measurement (not urine ketones) to monitor ketone clearance—urine ketones lag behind and can falsely suggest worsening. 1, 2

Resolution Criteria

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

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

Transition to Subcutaneous Insulin

• Administer long-acting basal insulin (glargine or detemir) subcutaneously 2–4 hours before stopping the IV insulin infusion to prevent rebound hyperglycemia and recurrent ketoacidosis. 1, 2
• Use approximately 50% of the total 24-hour IV insulin dose as the basal insulin dose, with the remaining 50% divided equally among three meals as rapid-acting insulin. 1
• Continue IV insulin for 1–2 hours after the basal dose to ensure adequate absorption. 1

Common Pitfalls to Avoid

• Never discontinue IV insulin without prior basal insulin administration—this is the most common error leading to DKA recurrence. 1, 2
• Never withhold dextrose when glucose falls during treatment—add dextrose to fluids while maintaining insulin to clear ketones. 1
• Never rely solely on urine ketones—they do not measure β-hydroxybutyrate and can be misleading during treatment. 1, 2
• Never use subcutaneous insulin in critically ill or unconscious patients—IV insulin is mandatory for hemodynamic instability or altered mental status. 1, 2