What insulin dose should I administer to a patient with hyperglycemia (elevated blood glucose) on a sliding scale insulin regimen with a blood glucose level of 420 mg/dL?

Management of Severe Hyperglycemia with Blood Glucose of 420 mg/dL

For a patient on sliding scale insulin with a blood glucose of 420 mg/dL, administer 4 units of rapid-acting insulin immediately and implement a basal-bolus insulin regimen as soon as possible to replace the sliding scale approach.

Immediate Management

For immediate correction of severe hyperglycemia (BG 420 mg/dL):

• According to American Diabetes Association guidelines, for blood glucose values >350 mg/dL, administer 4 units of rapid-acting insulin (such as insulin aspart) 1
• Recheck blood glucose in 1-2 hours to assess response
• Ensure adequate hydration

Problems with Sliding Scale Insulin Alone

Multiple guidelines strongly recommend against using sliding scale insulin as the sole treatment strategy:

• The American Diabetes Association and multiple other organizations explicitly recommend against sliding scale insulin alone for managing diabetes in hospitalized patients 2, 1
• Sliding scale insulin regimens are associated with a 3-fold higher risk of hyperglycemic episodes compared to other regimens 3
• Studies show that sliding scale insulin alone results in suboptimal glycemic control in 84% of cases 4
• Only 12% of sliding scale insulin injections successfully bring glucose levels to target range 4

Recommended Insulin Regimen

Implement a basal-bolus insulin regimen as soon as possible:

1. Calculate total daily insulin dose:

   • For insulin-naive patients: 0.3-0.5 units/kg/day 1
   • For a 70kg patient, this would be approximately 21-35 units total daily

2. Distribute insulin doses:

   • 50% as basal insulin (long-acting insulin like glargine or detemir)
   • 50% as prandial insulin (rapid-acting insulin divided before meals) 1

3. Add correction doses for hyperglycemia:

   • For BG >250 mg/dL: add 2 units of rapid-acting insulin
   • For BG >350 mg/dL: add 4 units of rapid-acting insulin 1

Blood Glucose Monitoring

• For patients who are eating: monitor before meals and at bedtime 1
• For patients not eating: monitor every 4-6 hours 1
• Target blood glucose range: 140-180 mg/dL for most hospitalized patients 1, 5

Common Pitfalls to Avoid

1. Continuing sliding scale insulin alone: Multiple studies show this approach leads to poor glycemic control 6, 3, 4

2. Inadequate monitoring: About 30% of sliding scale insulin administrations have documentation or timing issues 4

3. Failure to adjust insulin doses: Studies show that 81% of sliding scale regimens are never adjusted despite persistent hyperglycemia 4

4. Hypoglycemia risk: When implementing basal-bolus insulin, be aware of risk factors for hypoglycemia:

   • Low serum albumin levels
   • African American race
   • Renal impairment (reduce doses by 20-25% if present) 1, 3

The RABBIT 2 trial demonstrated that basal-bolus insulin regimens achieved target glucose levels in 66% of patients compared to only 38% with sliding scale insulin alone 6, making the basal-bolus approach clearly superior for managing inpatient hyperglycemia.