I administered 2 units of rapid‑acting insulin and the capillary blood glucose is now 427 mg/dL; what should I do next?

Immediate Management of Persistent Hyperglycemia After 2 Units of Insulin

Administer an additional 2-4 units of rapid-acting insulin immediately and recheck capillary blood glucose in 1-2 hours, while simultaneously investigating the underlying cause of this severe hyperglycemia.

Critical Assessment Required NOW

Rule Out Diabetic Ketoacidosis

• Check for ketones immediately (urine or blood) if this patient has type 1 diabetes or is insulin-dependent, especially if accompanied by nausea, vomiting, abdominal pain, or altered mental status 1
• For blood glucose >300 mg/dL (16.7 mmol/L), check for ketosis in ALL patients 1
• If ketonuria is present or ketonemia ≥0.5 mmol/L, suspect early ketoacidosis and call for immediate physician evaluation 1

Verify Insulin Potency and Administration

• Inspect the insulin vial immediately for changes including clumping, frosting, precipitation, or change in clarity/color that may signify loss of potency 1
• Confirm the insulin was administered correctly (proper dose drawn, injected subcutaneously, not intramuscularly) 1
• Verify the insulin has not been exposed to extreme temperatures (<36°F or >86°F) and has been stored properly 1
• If the vial has been in use >1 month, especially at room temperature, replace it with a new vial as potency may be compromised 1

Immediate Correction Dose Protocol

For Patients Already on Scheduled Insulin

• Give 2 units of rapid-acting insulin for pre-meal glucose >250 mg/dL (13.9 mmol/L) 1
• Give 4 units of rapid-acting insulin for pre-meal glucose >350 mg/dL (19.4 mmol/L) 1
• At 427 mg/dL (23.7 mmol/L), this patient requires 4 units of rapid-acting insulin immediately 1

Calculate Individualized Correction Dose

• Use the insulin sensitivity factor (ISF): ISF = 1500 ÷ Total Daily Dose (TDD) for regular insulin 2
• Correction dose = (Current glucose - Target glucose) ÷ ISF 2
• Example: If TDD is 30 units, ISF = 1500 ÷ 30 = 50 mg/dL per unit; correction = (427 - 125) ÷ 50 = 6 units 2

Critical Pitfall: This Patient Needs MORE Than Correction Insulin

The Fundamental Problem

• A blood glucose of 427 mg/dL indicates complete inadequacy of the current insulin regimen - this is NOT just a correction dose situation 1
• Sliding scale insulin as monotherapy is explicitly condemned by all major diabetes guidelines and shown to be ineffective 1
• Only 38% of patients receiving sliding scale alone reach mean blood glucose <140 mg/dL, versus 68% with scheduled basal-bolus regimens 1

Immediate Regimen Change Required

• Discontinue sliding scale insulin as the sole treatment immediately 1
• Start a scheduled basal-bolus insulin regimen with:
  • Basal insulin: 0.3-0.5 units/kg/day for severe hyperglycemia, given as 50% of total daily dose 1, 2
  • Prandial insulin: Remaining 50% divided among three meals using rapid-acting insulin 1, 2
• For a 70 kg patient with glucose 427 mg/dL, start with 21-35 units total daily (approximately 10-18 units basal + 3-6 units before each meal) 2

Monitoring and Follow-Up

Short-Term Monitoring (Next 2-4 Hours)

• Recheck capillary blood glucose in 1-2 hours after correction dose 1
• If glucose remains >300 mg/dL after 2 hours, give another correction dose and investigate further 1
• Monitor for symptoms of hypoglycemia as glucose begins to fall 1

Ongoing Monitoring Requirements

• Check capillary blood glucose before each meal and at bedtime once eating 3
• Continue every 1-2 hours if NPO and receiving glucose-containing infusions 3
• Daily fasting blood glucose monitoring is essential during titration 2

Address Foundation Therapy

Metformin Must Be Optimized

• Continue or start metformin at maximum tolerated dose (up to 2000-2550 mg daily) unless contraindicated 2
• Metformin reduces total insulin requirements and provides superior glycemic control when combined with insulin 2
• Never discontinue metformin when starting or intensifying insulin therapy 2

Common Pitfalls to Avoid

• Never rely solely on correction doses to manage persistent hyperglycemia - scheduled insulin doses must be established 1
• Never delay transition to scheduled insulin when blood glucose values are consistently >250 mg/dL 1
• Never give rapid-acting insulin at bedtime as a sole correction dose, as this markedly raises nocturnal hypoglycemia risk 1, 3
• Never assume 2 units was adequate - this dose is far too small for glucose of 427 mg/dL and indicates fundamental under-dosing 1, 2

When to Escalate Care Immediately

• If ketones are present (ketonuria ≥ trace or ketonemia ≥0.5 mmol/L) 1, 3
• If patient has nausea, vomiting, abdominal pain, or altered mental status 1
• If glucose remains >300 mg/dL despite two correction doses 1
• If patient is unable to take oral fluids or shows signs of dehydration 1