What Does Basal-Bolus Mean?
Basal-bolus insulin therapy is a physiologic insulin replacement strategy that combines long-acting "basal" insulin (given once or twice daily to control blood glucose between meals and overnight) with rapid-acting "bolus" insulin (given before each meal to cover postprandial glucose excursions), plus correction doses for elevated blood glucose. 1
Components of Basal-Bolus Therapy
The regimen consists of three distinct insulin components:
1. Basal Insulin
- Long-acting or intermediate-acting insulin administered once or twice daily
- Provides continuous background insulin coverage
- Restrains hepatic glucose production during fasting periods
- Examples include insulin glargine, detemir, degludec, or NPH insulin 2
2. Bolus (Prandial) Insulin
- Rapid-acting or short-acting insulin given before meals
- Covers postprandial glucose excursions
- Examples include insulin lispro, aspart, glulisine, or regular insulin 1
3. Correction Insulin
- Supplemental doses of rapid-acting insulin for blood glucose above target
- Customized to match individual insulin sensitivity
- Administered together with bolus insulin or separately if not eating 2
Dosing Strategy
For insulin-naive patients, the typical starting approach allocates approximately 50% of total daily insulin to basal dosing and 50% to prandial insulin (divided among three meals). 1 For example:
- Total daily dose: 0.3-0.5 units/kg for most patients
- If total daily dose = 40 units: 20 units basal + 20 units prandial (split as ~7 units before each meal)
- Lower doses (0.1-0.25 units/kg) for elderly patients, those with renal failure, or poor oral intake 1
Clinical Rationale
This approach mimics normal physiologic insulin secretion more closely than older regimens. Randomized trials consistently demonstrate superior glycemic control with basal-bolus therapy compared to sliding-scale insulin alone, with associated reductions in complications including postoperative wound infection, pneumonia, bacteremia, and acute renal and respiratory failure. 1
Important Caveats
The primary risk is hypoglycemia—basal-bolus insulin carries approximately 4-6 times higher risk of hypoglycemia than sliding-scale insulin alone, with mild hypoglycemia occurring in 12-30% of patients in controlled settings. 1
For patients with:
- Mild hyperglycemia (blood glucose <200 mg/dL)
- Decreased oral intake
- Undergoing surgery
Consider a "basal-plus" approach instead: single dose of basal insulin (0.1-0.25 units/kg/day) plus correction doses only, without scheduled prandial insulin. 1
Avoid sliding-scale insulin as the sole therapy in patients with established diabetes, particularly those with type 1 diabetes, as it treats hyperglycemia reactively rather than preventing it. 1