What is the next recommended dose of insulin to lower a hyperglycemic patient's glucose level after an initial 10 units of insulin subcutaneously (SC) resulted in a decrease from 517 mg/dL to 405 mg/dL over 2 hours, now with intravenous (IV) access and fluids started?

Management of Hyperglycemia in a Patient with IV Access

For a hyperglycemic patient whose glucose decreased from 517 mg/dL to 405 mg/dL after 10 units of subcutaneous insulin, the recommended next dose is 0.1 units/kg/hour of intravenous regular insulin (approximately 7-10 units/hour for an average adult) now that IV access has been established.

Assessment of Current Situation

The patient has shown some response to the initial subcutaneous insulin dose (glucose decreased by 112 mg/dL over 2 hours), but remains severely hyperglycemic at 405 mg/dL. Now that IV access and fluids have been established, a more effective insulin administration approach can be implemented.

Recommended Treatment Algorithm

1. Initial IV insulin dosing:

   • Start an IV insulin infusion at 0.1 units/kg/hour of regular insulin 1
   • For a 70-80 kg adult, this would be approximately 7-8 units/hour
   • No initial bolus dose is needed as the patient has already received subcutaneous insulin 2

2. IV fluid management:

   • Continue IV fluid resuscitation with 0.9% NaCl at a clinically appropriate rate 1
   • Aim to replace approximately 50% of the estimated fluid deficit in the first 8-12 hours

3. Monitoring protocol:

   • Check blood glucose hourly until stable
   • Check electrolytes, renal function, and venous pH every 2-4 hours 1
   • Monitor potassium levels closely and begin replacement when serum K+ <5.5 mEq/L 2

4. Insulin infusion adjustment:

   • Target a glucose reduction rate of 50-70 mg/dL/hour 2
   • If glucose is not decreasing at the desired rate, increase the insulin infusion rate by 1 unit/hour
   • If glucose is decreasing too rapidly (>100 mg/dL/hour), decrease the infusion rate

5. Glycemic targets:

   • For DKA: aim to keep glucose between 150-200 mg/dL until resolution 1
   • For HHS: target glucose between 200-250 mg/dL until resolution 1

Special Considerations

• Risk of hypoglycemia: The risk increases with higher insulin doses. Monitor glucose frequently and be prepared to administer IV dextrose if needed 1

• Potassium management: Insulin drives potassium into cells. Monitor potassium levels closely and supplement as needed to maintain levels between 4-5 mmol/L 1

• Transition to subcutaneous insulin: When the patient is stable and able to eat, administer subcutaneous basal insulin 2 hours before discontinuing the IV insulin infusion to prevent rebound hyperglycemia 1

Pitfalls to Avoid

• Sole use of correction insulin: Using only correction insulin without basal insulin (sliding scale approach) is discouraged as it leads to poor glycemic control 1

• Abrupt discontinuation of IV insulin: This can lead to rebound hyperglycemia if not properly transitioned to subcutaneous insulin 1

• Inadequate fluid resuscitation: Fluid replacement is as important as insulin therapy in the management of hyperglycemic crises 1

• Overaggressive glucose correction: Too rapid correction of glucose can lead to complications including cerebral edema, particularly in children and young adults 2

The evidence strongly supports using intravenous insulin infusion now that IV access has been established, as this provides more predictable absorption and effect compared to continued subcutaneous dosing in a patient with persistent severe hyperglycemia.