How do I transition a patient from a regular insulin sliding scale to a fixed dose of insulin?

Transitioning from Sliding Scale to Fixed-Dose Insulin

Discontinue sliding scale insulin immediately and initiate a basal-bolus insulin regimen, which provides superior glycemic control and reduces hospital complications compared to reactive sliding scale dosing alone. 1, 2

Why Sliding Scale Insulin Should Be Abandoned

• Sliding scale insulin is strongly discouraged as the sole treatment for hospitalized patients with diabetes because it treats hyperglycemia reactively rather than proactively, leading to poor glycemic control and rapid blood glucose fluctuations 1
• Randomized controlled trials consistently demonstrate that basal-bolus regimens achieve better glycemic control (68% vs 38% achieving mean glucose <140 mg/dL) and reduce complications including postoperative wound infections, pneumonia, bacteremia, and acute renal failure compared to sliding scale insulin alone 1, 2
• Sliding scale insulin should never be used as monotherapy in patients with type 1 diabetes 1

Calculate the Total Daily Insulin Dose

For Insulin-Naive Patients or Those on Low Doses:

• Start with 0.3-0.5 units/kg/day as the total daily insulin dose 1, 2
• Use lower doses (0.3 units/kg/day) for patients at higher risk of hypoglycemia: elderly patients (>65 years), those with renal failure, or poor oral intake 1, 2

For Patients Already on Higher Insulin Doses at Home:

• Reduce the home total daily insulin dose by 20% during hospitalization to prevent hypoglycemia 2

For Patients Transitioning from IV Insulin:

• Calculate the total daily dose as 60-80% of the 24-hour IV insulin infusion amount, or use the average insulin infused during the previous 12 hours and multiply by 2 1

Divide the Total Daily Dose into Basal and Bolus Components

• Allocate 50% to basal insulin (given once or twice daily as long-acting insulin such as glargine, detemir, or NPH) 1, 2
• Allocate 50% to rapid-acting prandial insulin (divided equally before three meals as lispro, aspart, or regular insulin) 1, 2

Example Calculation:

For a 70 kg patient starting at 0.4 units/kg/day:

• Total daily dose = 70 kg × 0.4 = 28 units/day
• Basal insulin = 14 units once daily (or 7 units twice daily if using NPH)
• Prandial insulin = 14 units total, divided as ~5 units before each meal 1, 2

Add Correction Insulin

• Continue using correction-dose rapid-acting insulin in addition to scheduled basal-bolus doses to address unexpected hyperglycemia 1, 2
• A simplified approach: give 2 units for premeal glucose >250 mg/dL and 4 units for premeal glucose >350 mg/dL 2
• If correction doses are frequently required, increase the scheduled basal or prandial insulin doses accordingly rather than continuing to rely on corrections 2

Timing and Administration

• Administer basal insulin once daily (with evening meal or at bedtime) or twice daily if using NPH insulin 3
• Give prandial insulin immediately before meals for patients eating regularly 1
• For patients with poor or uncertain oral intake, administer prandial insulin immediately after meals with the dose adjusted based on actual intake 1
• Point-of-care glucose testing should be performed immediately before meals 1

Target Glucose Range

• Target 140-180 mg/dL for most hospitalized patients 1, 2
• Tighter control (100-140 mg/dL) may be considered in cardiac surgery patients using computerized algorithms that minimize hypoglycemia risk, but this approach has not shown additional benefit in other populations and increases hypoglycemia risk 1

Common Pitfalls to Avoid

• Do not use premixed insulin formulations in the hospital setting—they are associated with unacceptably high rates of hypoglycemia compared to basal-bolus regimens 1, 2
• Do not continue sliding scale insulin as monotherapy even if it appears to be "working"—studies show no benefit and potential harm 4, 5
• Monitor for hypoglycemia, which occurs in 12-30% of patients on basal-bolus regimens in controlled settings 2
• Review the insulin regimen any time blood glucose falls below 70 mg/dL as this predicts subsequent severe hypoglycemia 1

Special Populations

• For patients with mild stress hyperglycemia without a diabetes diagnosis, sliding scale insulin alone may be appropriate 1
• For patients with type 1 diabetes, basal insulin is absolutely required—never use sliding scale insulin alone 1