What is the recommended approach for dosing insulin in an inpatient setting?

Inpatient Insulin Dosing Protocol

For inpatient insulin management, a basal-bolus insulin regimen is strongly recommended over sliding scale insulin alone, as it provides better glycemic control and reduces hospital complications.

Critical Care Setting

• Continuous intravenous insulin infusion is the most effective method for achieving glycemic targets in critically ill patients 1
• Infusions should be administered using validated written or computerized protocols that allow for predefined adjustments based on glycemic fluctuations 1
• For diabetic ketoacidosis (DKA) and hyperglycemic hyperosmolar state (HHS), continuous intravenous insulin infusion is recommended 1

Non-Critical Care Setting

For Patients with Poor or No Oral Intake:

• Basal insulin or a basal plus correction insulin regimen is preferred 1
• NPH insulin administered twice or three times daily (every 8 or 12 h) is recommended for patients on enteral nutrition 1
• Correctional insulin should be administered subcutaneously every 6 h using human regular insulin or every 4 h using rapid-acting insulin 1

For Patients with Adequate Nutritional Intake:

• An insulin regimen with basal, prandial, and correction components is preferred 1
• For patients who are eating, insulin injections should align with meals 1
• Point-of-care glucose testing should be performed immediately before meals 1
• If oral intake is poor, administer prandial insulin immediately after the patient eats, with the dose adjusted to the amount ingested 1

Dosing Guidelines:

• Starting total daily insulin dose: 0.3-0.5 units/kg/day for insulin-naïve patients 2, 3
• Lower starting doses (0.2-0.3 units/kg/day) for elderly patients or those with renal impairment 2
• Distribute total daily dose as:
  • 50% as basal insulin (once or twice daily)
  • 50% as prandial insulin divided before meals 3, 4

Converting from IV to Subcutaneous Insulin

• Calculate 60-80% of the total daily insulin requirement from the IV infusion based on the average hourly rate during the final 6 hours of stable glycemic control 5
• Administer first dose of subcutaneous basal insulin 2 hours before discontinuing the IV insulin infusion 1, 5
• Example calculation: If average IV insulin rate is 1.5 units/hour, the estimated 24-hour requirement would be 36 units; convert to 60-80% (22-29 units) for subcutaneous dosing 5

Special Considerations

Type 1 Diabetes:

• An insulin regimen with basal and correction components is necessary for all hospitalized patients with type 1 diabetes, even when NPO 1
• Basal insulin should never be held for patients with type 1 diabetes, especially during care transitions 1

Enteral/Parenteral Nutrition:

• For patients receiving enteral feedings, calculate insulin for nutritional component as 1 unit per 10-15g carbohydrate in the formula 1
• For continuous feedings, consider NPH insulin every 8-12 hours 1
• For bolus feedings, give approximately 1 unit of regular human insulin or rapid-acting insulin per 10-15g carbohydrate before each feeding 1

Avoiding Common Pitfalls

• Prolonged use of sliding scale insulin alone is strongly discouraged as it results in poorer glycemic control and increased complications 1
• Premixed insulin formulations are not routinely recommended for in-hospital use due to increased risk of hypoglycemia 1, 2
• Monitor for hypoglycemia, especially during overnight hours (midnight to 6:00 A.M.) when risk is highest 1
• Implement a standardized hospital-wide hypoglycemia prevention and management protocol 1
• Ensure meal delivery and nutritional insulin coverage are coordinated to prevent hyper/hypoglycemic events 1

Medication Considerations

• SGLT2 inhibitors should be discontinued 3-4 days before surgery and avoided during hospitalization 1
• Metformin should be withheld on the day of surgery 1
• Insulin glargine should be administered at the same time each day, but can be given at any time of day 6
• Do not dilute or mix insulin glargine with any other insulin or solution 6

By following these evidence-based recommendations, you can optimize glycemic control while minimizing the risk of hypoglycemia in hospitalized patients with diabetes.