What is the proper preparation and administration of 5% dextrose in half‑strength normal saline for a patient with diabetic ketoacidosis whose plasma glucose is about 200‑250 mg/dL while receiving a regular insulin infusion?

Administration of 5% Dextrose with Half-Normal Saline in DKA

Direct Answer

When plasma glucose reaches 200-250 mg/dL during DKA treatment with insulin infusion, switch from 0.9% normal saline to 5% dextrose in 0.45-0.75% NaCl (half-normal to three-quarter normal saline), continuing at the same infusion rate used for initial fluid resuscitation. 1, 2

Specific Protocol for Implementation

Glucose Threshold for Switching Fluids

• Change to dextrose-containing fluids when blood glucose falls to 250 mg/dL or below during active DKA treatment with insulin infusion 1, 2
• The American Diabetes Association specifically recommends 5% dextrose in 0.45-0.75% NaCl as the replacement fluid 1
• Continue the same infusion rate that was used for crystalloid replacement, targeting 50% of estimated fluid deficit replacement over the first 8-12 hours 1

Critical Insulin Management

Do not stop or reduce the insulin infusion when adding dextrose 1

• Continue insulin at 0.05-0.10 units/kg/hour (the standard DKA rate) until DKA resolves 3, 1
• The goal is to continue clearing ketones while preventing hypoglycemia with concurrent dextrose administration 1
• DKA resolution is defined as pH >7.3, bicarbonate >15 mEq/L, and anion gap closure 1

Monitoring Requirements

Check blood glucose every 1-2 hours during dextrose infusion 2

• Monitor electrolytes, renal function, venous pH, and osmolality every 2-4 hours until stable 1
• Maintain potassium levels between 4-5 mEq/L throughout treatment 1
• Do not administer insulin if serum potassium is <3.3 mEq/L until potassium is restored, as insulin drives potassium into cells and can cause life-threatening arrhythmias 4

Common Pitfalls and How to Avoid Them

Hypoglycemia Risk

• Hypoglycemia occurs more frequently with fixed-rate insulin protocols that don't incorporate adequate dextrose 5
• When glucose values fall below 100 mg/dL, intervene aggressively to prevent frank hypoglycemia 5
• The two-bag method (having both dextrose-containing and non-dextrose bags running simultaneously with adjustable rates) reduces hypoglycemia risk and allows faster DKA resolution 6

Euglycemic DKA Considerations

• In euglycemic DKA (glucose <200 mg/dL with severe acidosis), higher dextrose concentrations (10% or 20%) may be required to facilitate administration of the large insulin doses needed to correct severe acidosis 7
• This scenario is increasingly common with SGLT2 inhibitor use, pregnancy, decreased caloric intake, or alcohol use 7

Fluid Composition Selection

• The range of 0.45-0.75% NaCl (half-normal to three-quarter normal saline) allows adjustment based on serum sodium levels 1
• Use 0.45% NaCl if sodium is elevated, 0.75% NaCl if sodium is low-normal 1

Pediatric Differences

• For pediatric patients, the same 250 mg/dL glucose threshold applies for adding dextrose 1
• Pediatric maintenance rates are approximately 100 mL/kg per 24 hours (7 mg/kg per minute) when using 10% dextrose 3, 1

Practical Administration Steps

1. Confirm glucose is 200-250 mg/dL while on insulin infusion 1, 2
2. Switch IV fluid to 5% dextrose in 0.45-0.75% NaCl 1
3. Maintain the same infusion rate as the initial crystalloid resuscitation 1
4. Continue insulin at 0.05-0.10 units/kg/hour without reduction 1
5. Add 20-30 mEq potassium to each liter of IV fluid once potassium is restored to ≥3.3 mEq/L 4
6. Monitor glucose hourly and electrolytes every 2-4 hours 1, 2