What is the recommended approach to initiate insulin therapy in hospitalized patients?

How to Start Insulin in Admitted Patients

For hospitalized patients requiring insulin initiation, use a basal-bolus regimen with weight-based dosing (0.3-0.5 units/kg/day for insulin-naive patients, divided 50% basal and 50% prandial) for those eating well, or basal plus correction insulin (0.1-0.25 units/kg/day) for those with poor oral intake—never use sliding scale insulin alone. 1, 2

Glycemic Targets

Before initiating insulin, establish appropriate glucose targets:

• Target range: 140-180 mg/dL for most hospitalized patients (both critically ill and non-critically ill) 1, 2
• Pre-meal target: <140 mg/dL for non-critically ill patients with good oral intake 1
• More stringent targets (110-140 mg/dL) may be considered only for stable patients with prior tight outpatient control, but only if achievable without significant hypoglycemia 1, 2

Route Selection Based on Clinical Status

Critically Ill Patients (ICU Setting)

Use continuous intravenous insulin infusion as the preferred method 1, 2:

• Administer using validated written or computerized protocols 2
• Monitor blood glucose every 30 minutes to 2 hours 2
• Target glucose range: 140-180 mg/dL 1, 2

Non-Critically Ill Patients

Use subcutaneous insulin regimens based on nutritional status 1:

Subcutaneous Insulin Initiation Algorithms

For Patients with Good Nutritional Intake (Eating Regular Meals)

Basal-Bolus-Correction Regimen 1, 2:

Starting dose calculation:

• Total daily dose (TDD): 0.3-0.5 units/kg/day for insulin-naive patients 1, 2
• Basal insulin: 50% of TDD given once daily 1, 2
• Prandial insulin: 50% of TDD divided equally before three meals 1, 2
• Correction insulin: Add rapid-acting insulin as needed 1

Specific basal insulin options:

• Insulin glargine: 10 units subcutaneously once daily (if no prior insulin use) 1
• NPH/detemir: 5 units subcutaneously every 12 hours (alternative option) 1

Prandial insulin:

• Use rapid-acting analogs (lispro, aspart, or glulisine) given 0-15 minutes before meals 1, 3
• Dose based on carbohydrate content: approximately 1 unit per 10-15 grams of carbohydrate 1

For Patients with Poor or No Oral Intake (NPO or Minimal Intake)

Basal Plus Correction Regimen 1, 2:

• Lower basal insulin dose: 0.1-0.25 units/kg/day 2
• No scheduled prandial insulin (since not eating) 1
• Correction insulin every 4-6 hours using rapid-acting insulin 1

Critical pitfall: Patients who are NPO should NOT receive prandial insulin, only basal plus correction doses 1

For Patients Already on Insulin at Home

Calculate basal needs from preadmission regimen 1:

• If on long-acting or intermediate insulin: use 30-50% of total daily home dose as basal component 1
• Switching from NPH once daily: Use same dose of glargine 4
• Switching from NPH twice daily: Use 80% of total NPH dose as once-daily glargine 4

Special Clinical Scenarios

Enteral Tube Feedings

For continuous tube feedings 1:

• Calculate total daily nutritional insulin as 1 unit per 10-15 grams carbohydrate per day 1
• This represents 50-70% of total daily insulin dose 1
• Use basal insulin (NPH every 8 hours, detemir every 12 hours, or glargine every 24 hours) 1
• Add correction insulin every 4-6 hours 1

For bolus tube feedings 1:

• Give 1 unit regular or rapid-acting insulin per 10-15 grams carbohydrate before each feeding 1
• Add correction insulin before each feeding 1

Glucocorticoid Therapy

For patients on steroids (particularly dexamethasone or prednisone) 1:

• Morning steroid regimens: Use NPH insulin (prandial dosing pattern) due to disproportionate daytime hyperglycemia 1
• Long-acting or continuous steroids: Require long-acting basal insulin plus increased prandial and correction doses 1
• Starting dose for high-dose steroids: 1.0-1.2 units/kg/day (25% basal, 75% prandial) 1
• For patients without diabetes on steroids: Consider single morning dose of NPH (0.1-0.3 units/kg/day) 1

Critical adjustment: Insulin requirements decline rapidly when steroids are stopped—adjust doses immediately 1

Parenteral Nutrition

For continuous parenteral nutrition 1:

• Add regular insulin directly to solution if >20 units correction insulin needed in past 24 hours 1
• Starting dose: 1 unit regular insulin per 10 grams dextrose 1
• Adjust daily in the solution 1
• Provide subcutaneous correction insulin separately 1

Transitioning from IV to Subcutaneous Insulin

When moving patients from IV insulin infusion to subcutaneous therapy 2:

1. Calculate 24-hour insulin requirement based on average hourly infusion rate over previous 12 hours 2
2. Administer first subcutaneous basal insulin dose 2-4 hours BEFORE discontinuing IV infusion 2
3. This prevents rebound hyperglycemia 1, 2

Monitoring Requirements

Blood glucose monitoring frequency 2:

• Patients eating: Before each meal and at bedtime 2
• Patients NPO: Every 4-6 hours 2
• Patients on IV insulin: Every 30 minutes to 2 hours 2

Critical Pitfalls to Avoid

Never Use Sliding Scale Insulin (SSI) Alone

SSI as monotherapy is strongly discouraged and ineffective 1, 5:

• SSI treats hyperglycemia reactively after it occurs rather than preventing it 1, 5
• Associated with clinically significant hyperglycemia and poor outcomes 5
• One study showed only 38% achieved glucose control with SSI versus 68% with basal-bolus regimen 1

The ONLY acceptable use of SSI alone: Patients without established diabetes who have mild stress hyperglycemia 5

Type 1 Diabetes Patients

Always maintain basal insulin in Type 1 diabetes patients 2, 5:

• Never use SSI alone in Type 1 diabetes 5
• These patients require continuous basal insulin to prevent diabetic ketoacidosis 2
• Even if NPO, they need basal insulin 2

Hypoglycemia Prevention

Implement systematic hypoglycemia prevention 1, 2:

• Review and adjust regimen when glucose falls <100 mg/dL 1, 2
• Modify regimen when glucose <70 mg/dL unless easily explained (e.g., missed meal) 1
• Document all hypoglycemic episodes for quality tracking 2
• Common triggers: NPO status without insulin adjustment, interrupted tube feedings, reduced steroid doses 1

Renal Insufficiency

Use lower insulin doses in patients with renal impairment 2, as insulin clearance is reduced and hypoglycemia risk increases.

Admission Orders

Initial admission orders should include 1:

• Document type of diabetes (Type 1, Type 2, gestational, pancreatic) 1
• Obtain HbA1c if not available from previous 3 months 1, 5
• Assess diabetes self-management knowledge 1
• Implement structured insulin order sets using computerized physician order entry (CPOE) when available 1

Self-Management Considerations

Selected patients may continue self-management in hospital 1, 2:

• Must have stable consciousness and insulin requirements 1, 2
• Successfully self-manage at home with multiple daily injections or pump therapy 1
• Proficient in carbohydrate counting and sick-day management 1
• Requires agreement between patient, physician, and nursing staff 1