Administration of Dextrose with Insulin in Hyperglycemia
Dextrose should be added to intravenous fluids when plasma glucose falls to 250 mg/dL in diabetic ketoacidosis (DKA) or 300 mg/dL in hyperosmolar hyperglycemic state (HHS), while continuing insulin infusion at a reduced rate to allow resolution of the underlying metabolic derangement without causing hypoglycemia. 1
The Core Principle: Why Give Dextrose During Insulin Treatment
The fundamental concept is that insulin must be continued beyond glucose normalization to clear ketones in DKA or resolve hyperosmolarity in HHS, which takes substantially longer than correcting hyperglycemia alone. 1 Ketonemia typically requires many more hours to resolve than hyperglycemia, and stopping insulin prematurely when glucose normalizes will allow the metabolic crisis to persist or worsen. 1
Specific Protocol for DKA and HHS
Initial Insulin Phase (Before Dextrose)
- Start continuous IV regular insulin at 0.1 units/kg/hour (typically 5-7 units/hour in adults) after excluding hypokalemia (K+ >3.3 mEq/L). 1
- This should decrease plasma glucose by 50-75 mg/dL per hour. 1
- If glucose doesn't fall by at least 50 mg/dL in the first hour, double the insulin infusion rate hourly until achieving steady decline. 1
Transition Point: When to Add Dextrose
When plasma glucose reaches 250 mg/dL in DKA or 300 mg/dL in HHS, make these simultaneous adjustments: 1
- Reduce insulin infusion to 0.05-0.1 units/kg/hour (3-6 units/hour). 1
- Add 5-10% dextrose to the intravenous fluids. 1
- Continue both insulin and dextrose until the metabolic crisis resolves (acidosis clears in DKA, or mental status and hyperosmolarity normalize in HHS). 1
Ongoing Adjustments
- Adjust either the insulin infusion rate or the dextrose concentration to maintain glucose in the target range (250 mg/dL for DKA, 300 mg/dL for HHS) until resolution. 1
- Monitor glucose every 2-4 hours during this phase. 1
Critical Pitfalls to Avoid
Never stop insulin when glucose normalizes - this is the most common error. The underlying ketoacidosis or hyperosmolar state will persist or worsen without continued insulin, even if glucose is normal. 1 This is why dextrose administration is essential: it allows continued insulin therapy while preventing hypoglycemia.
Do not use sliding-scale insulin alone in hospitalized diabetic patients, as this approach treats hyperglycemia only after it occurs and is associated with worse outcomes. 1
Non-Crisis Hyperglycemia Management
For general inpatient hyperglycemia management (not DKA/HHS), the approach differs:
- Target glucose 140-180 mg/dL for most hospitalized patients. 1
- Use scheduled basal-bolus insulin regimens rather than sliding scale alone. 1
- If a patient on continuous insulin infusion needs transition to subcutaneous insulin, give the subcutaneous dose 1-2 hours before stopping the IV infusion to prevent rebound hyperglycemia. 1
- When discontinuing IV insulin, consider using basal insulin at 60-80% of the 24-hour IV insulin dose. 1
Special Consideration: Preventing Rebound Hypoglycemia
When stopping concentrated dextrose infusions, follow with 5% or 10% dextrose to avoid rebound hypoglycemia, as the body's insulin response may persist after the glucose source is removed. 2 This is particularly important in patients who have been receiving high-concentration dextrose solutions.
Monitoring Requirements
- Check blood glucose every 2-4 hours during active management of hyperglycemic crises. 1
- Monitor serum electrolytes (especially potassium and phosphate) every 2-4 hours, as these can become depleted during treatment. 1, 2
- In DKA, follow venous pH and anion gap rather than repeated arterial blood gases to assess resolution. 1