How should Humulin R (Regular insulin) be dosed in a diabetic patient using a sliding scale regimen, starting with 20 units?

Humulin R 20 Units with Sliding Scale Dosing

Sliding scale insulin as monotherapy is explicitly condemned by all major diabetes guidelines and should be immediately replaced with a scheduled basal-bolus regimen. 1

Critical Problems with Sliding Scale Monotherapy

• Sliding scale insulin treats hyperglycemia reactively after it occurs rather than preventing it, leading to dangerous glucose fluctuations and suboptimal control. 1, 2
• Randomized trials demonstrate that scheduled basal-bolus therapy provides superior glycemic control with reduced hospital complications compared to sliding scale monotherapy. 1, 2
• The American Diabetes Association explicitly states that sliding scale insulin alone should never be used as the sole treatment approach. 1

Recommended Insulin Regimen Structure

All patients requiring insulin should be on a scheduled regimen with basal, prandial, and correction components—not correction insulin alone. 1, 2

For Type 2 Diabetes Patients:

Basal Insulin Initiation:

• Start with 10 units of long-acting basal insulin (glargine, detemir, or degludec) once daily at the same time each day, OR use 0.1-0.2 units/kg body weight. 1, 2
• Continue metformin unless contraindicated, as this combination provides superior glycemic control with reduced insulin requirements and less weight gain. 1, 2

Basal Insulin Titration:

• Increase by 2 units every 3 days if fasting glucose is 140-179 mg/dL. 1, 2
• Increase by 4 units every 3 days if fasting glucose is ≥180 mg/dL. 1, 2
• Target fasting plasma glucose: 80-130 mg/dL. 1, 2
• If hypoglycemia occurs without clear cause, reduce dose by 10-20% immediately. 1, 2

Adding Prandial Coverage:

• When basal insulin exceeds 0.5 units/kg/day or when fasting glucose is controlled but HbA1c remains elevated after 3-6 months, add prandial insulin. 1, 2
• Start with 4 units of rapid-acting insulin (lispro, aspart, or glulisine) before the largest meal, OR use 10% of the basal dose. 1, 3
• Titrate prandial insulin by 1-2 units or 10-15% every 3 days based on 2-hour postprandial glucose readings. 1, 3

Correction Insulin Protocol:

• Use rapid-acting insulin as an adjunct to scheduled doses, not as monotherapy. 1, 2
• For premeal glucose >250 mg/dL: add 2 units of rapid-acting insulin. 2, 3
• For premeal glucose >350 mg/dL: add 4 units of rapid-acting insulin. 2, 3

For Type 1 Diabetes Patients:

• Start with total daily dose of 0.5 units/kg/day, divided as 50% basal insulin and 50% prandial insulin split among three meals. 2
• Adjust based on carbohydrate-to-insulin ratios and insulin sensitivity factors. 2

Converting from Humulin R Sliding Scale

If currently using Humulin R 20 units with sliding scale:

1. Calculate total daily insulin requirement: If the patient has been receiving an average of 20 units daily via sliding scale, this represents inadequate coverage. 1, 2

2. Implement basal-bolus regimen:

   • Start basal insulin at 10-20 units once daily (or 0.3-0.5 units/kg for severe hyperglycemia). 1, 2
   • Add prandial insulin at 4 units before each meal if HbA1c >9% or blood glucose consistently >300 mg/dL. 1, 2

3. Discontinue sliding scale monotherapy immediately and use correction doses only as adjunct to scheduled insulin. 1, 2

Monitoring Requirements

• Check fasting blood glucose daily during titration phase. 1, 2
• Check pre-meal and 2-hour postprandial glucose to guide prandial insulin adjustments. 1, 2
• Reassess every 3 days during active titration and every 3-6 months once stable. 1, 2

Critical Pitfalls to Avoid

• Never continue sliding scale insulin as monotherapy—this approach is ineffective and dangerous. 1, 2
• Never give rapid-acting insulin at bedtime to avoid nocturnal hypoglycemia. 1, 2
• Never continue escalating basal insulin beyond 0.5-1.0 units/kg/day without adding prandial coverage, as this leads to overbasalization with increased hypoglycemia risk. 1, 2
• Never discontinue metformin when starting insulin unless contraindicated, as this leads to higher insulin requirements and more weight gain. 1, 2