Basal Insulin Regimen for Diabetes

What is a Basal Regimen?

Available Basal Insulin Preparations

Basal Insulin Alone (Starting Regimen for Type 2 Diabetes)

Starting Dose

• Conservative: 10 units at bedtime (9:00 PM), regardless of weight
• Weight-based: 0.2 units/kg/day (or 0.4 units/kg for obese, insulin-resistant, or symptomatic patients)

Titration Protocols

• Start: 10 units at 9:00 PM
• Titrate: +1 unit/night until fasting glucose ≤110 mg/dL
• Alternative: +5 units every Monday

• Start: 10 units at 9:00 PM
• 3-day average fasting glucose drives dose adjustment:
  • <80 mg/dL → -3 units
  • 80-110 mg/dL → no change

  • 110 mg/dL → +3 units

• Perpetual self-titration (do not stop unless instructed)

• Start: 0.4 units/kg at 9:00 PM
• Titrate: +5 units each Monday up to maximum 60 units
• Once 60 units reached, either add prandial insulin (basal-plus) or reduce basal by 20% and add a GLP-1 receptor agonist

Basal-Bolus Regimen (Intensified/Type 1 Diabetes)

Total Daily Dose (TDD) Calculation

• TDD = weight (kg) × 0.7 units (for T1DM)
• Conservative start: 0.4 units/kg/day, then uptitrate
• Range: 0.5-0.8 units/kg/day for average non-obese patients

Dose Split

• Basal = 50% of TDD (given once daily at a consistent time)
• Bolus = 50% of TDD (split equally across 3 meals; ~0.1 units/kg/meal)
• Some patients require a 40:60 split favoring bolus

Prandial Insulin Administration

• Inject 15 minutes before meals
• If pre-meal glucose <80 mg/dL, inject at the onset of the meal
• Rapid-acting analogs preferred: lispro, aspart, glulisine

Prandial Dose Adjustments

Correction (Sliding Scale) Component

Basal-Plus Regimen (Intermediate Intensification)

• Basal insulin (glargine/detemir/degludec) once daily
• One prandial injection added at the largest meal of the day
• Stepwise - additional prandial doses added if targets are not met

Monitoring and Targets

• SMBG before meals and 2 hours after each meal (or CGM)
• Fasting glucose target: 80-130 mg/dL
• 2-hour postprandial target: <180 mg/dL
• If 2-hour postprandial glucose is consistently >50 mg/dL above pre-meal, increase prandial dose by 1-2 units
• If fasting glucose is consistently >130 mg/dL, increase basal dose by 5-10% daily
• Adjust down if fasting glucose <80 mg/dL to avoid nocturnal hypoglycemia

Key Drug Interactions / Combinations

• Continue metformin with insulin - shown to be effective and reduces insulin dose
• GLP-1 agonists can be continued or added (reduce basal dose by ~20% when adding)
• SGLT2 inhibitors and DPP-4 inhibitors can be continued in selected patients
• Pioglitazone + insulin is possible but increases weight gain and edema
• Sulfonylureas can be continued but raise hypoglycemia risk

Special Situations

• CKD: No specific regimen recommended; basal-bolus principles still apply with dose reduction and close monitoring
• Perioperative: Basal insulin regimen is superior to sliding scale alone on general surgical wards; generally continue basal regardless of NPO status (do not hold without direct order)
• Insulin pump (CSII): Delivers continuous basal rate programmed by the clinician; preferred for T1DM patients who cannot meet goals on MDI or who have frequent hypoglycemia or the dawn phenomenon

Recent Evidence (2024-2026)

1. Once-weekly basal insulin Fc vs. degludec (PMID 40509887, 2025): A meta-analysis examining CGM metrics showed once-weekly insulin Fc had comparable glycemic control and hypoglycemia rates to daily degludec - a potential future convenience option.
2. Premixed vs. basal-bolus intensification in T2DM (PMID 39907628, 2025): Premixed regimens showed similar HbA1c reduction to basal-bolus but with different hypoglycemia profiles - still considered second-line to basal-bolus for most patients.
3. Network meta-analysis of insulin regimens in T2DM (PMID 41436667, 2026 - Diabetologia): Compared all major regimens head-to-head; basal-bolus generally achieved greatest HbA1c reduction, with trade-offs in hypoglycemia and weight.