What infusion rate should be used for DNS (5% dextrose in 0.9% saline) in a patient on an insulin infusion to maintain blood glucose between 150–200 mg/dL?

DNS Infusion Rate During Insulin Therapy

When a patient is on an insulin infusion and requires dextrose-containing fluids to maintain blood glucose between 150-200 mg/dL, start DNS (D5NS) alongside the insulin infusion at a rate that prevents hypoglycemia while maintaining target glucose levels. Based on the most recent 2025 ADA guidelines, this typically means initiating dextrose-containing fluids when glucose approaches the lower end of your target range 1.

Practical Approach to DNS Rate

The infusion rate should be titrated based on glucose monitoring every 1-2 hours, with typical starting rates around 75-125 mL/hr of D5NS (providing approximately 4-6 grams of dextrose per hour). This translates to roughly 0.5-1 mL/min of 5% dextrose solution 2.

Key Principles:

• During active insulin infusion: The 2025 ADA guidelines specifically state that when glucose drops toward target range during DKA/HHS management, dextrose-containing fluids should be started alongside continued insulin infusion to maintain glucose between 150-200 mg/dL until resolution 1

• Avoid hyperglycemia: Research shows that even 500 mL of D5NS can cause significant hyperglycemia (>10 mmol/L or 180 mg/dL) in 72% of patients 3. During active insulin infusion, this risk is mitigated, but rates still need careful titration

• Perioperative considerations: Computer simulations suggest that during surgery and immediate postoperative period, glucose infusion rates should be reduced by 50-75% compared to baseline to avoid hyperglycemia - meaning no more than 0.5 mL/min (30 mL/hr) of D5 solution if strict normoglycemia is desired 2

Monitoring and Adjustment Algorithm

1. Check glucose every 1-2 hours while on insulin infusion 4, 5

   • More frequent monitoring (every 15-30 minutes) may be needed during initial titration 6

2. Adjust DNS rate based on glucose trend:

   • If glucose dropping toward 150 mg/dL: Increase DNS rate by 25-50 mL/hr
   • If glucose rising above 200 mg/dL: Decrease DNS rate by 25-50 mL/hr or increase insulin rate
   • If glucose stable 150-200 mg/dL: Continue current rate

3. Typical DNS rates in practice:

   • Standard maintenance: 75-125 mL/hr of D5NS
   • Can provide up to 0.5 g/kg/hr of dextrose (approximately 35 g/hr or 700 mL/hr of D5NS for a 70 kg patient) 6
   • Most patients require much less than maximum rates

Critical Caveats

Never use DNS alone without insulin in hyperglycemic patients - this will worsen hyperglycemia. The dextrose is added specifically to prevent hypoglycemia while continuing necessary insulin therapy 1.

Avoid overly aggressive dextrose administration: The 2010 AHA guidelines for beta-blocker overdose (which also uses insulin-dextrose infusions) recommend 0.5 g/kg/hr of dextrose with very frequent glucose monitoring, but this is for a specific toxicologic indication 6. For routine glycemic management, lower rates are appropriate.

The half-life of glucose during insulin infusion is approximately 30 minutes, meaning glucose will continue to rise for another 25% after initiating or increasing DNS rate 2. Wait at least 1 hour before making further rate adjustments unless glucose is critically low.

In DKA/HHS specifically: The 2025 ADA guidelines emphasize that dextrose-containing fluids should be added when glucose reaches 200-250 mg/dL (for HHS) or 150-200 mg/dL (for DKA) to allow continued insulin administration until metabolic resolution 1.