What is the recommended approach for basal bolus insulin preparation?

Basal-Bolus Insulin Preparation

For insulin-naive patients with type 2 diabetes requiring basal-bolus therapy, start with a total daily dose of 0.3-0.5 units/kg, split 50% as basal insulin (once or twice daily) and 50% as rapid-acting prandial insulin (divided equally before three meals), with lower doses (0.1-0.2 units/kg) for high-risk patients including those over 65 years, with renal failure, or poor oral intake. 1

Initial Dosing Strategy

For Insulin-Naive Patients

• Calculate total daily dose (TDD): 0.3-0.5 units/kg body weight 1
• Distribute as follows:
  • 50% as basal insulin (given once or twice daily) 1
  • 50% as rapid-acting prandial insulin (divided into three equal pre-meal doses) 1

Risk-Based Dose Reduction

Use lower starting doses (0.1-0.25 units/kg/day) for patients at higher hypoglycemia risk: 1

• Age >65 years 1
• Renal failure 1
• Poor or unpredictable oral intake 1
• Patients undergoing surgery 1

For Patients Already on Home Insulin

If the patient is on ≥0.6 units/kg/day at home, reduce total daily dose by 20% during hospitalization to prevent hypoglycemia related to decreased oral intake. 1

Stepwise Intensification Approach

Starting from Basal Insulin Alone

When basal insulin is optimized but A1C remains above goal: 1

1. Add single prandial dose: Start with 4 units or 10% of basal dose before the largest meal or meal with greatest postprandial glucose excursion 1
2. Titrate: Increase by 1-2 units or 10-15% twice weekly based on glucose response 1
3. Consider reducing basal: If A1C <8%, lower basal dose by 4 units or 10% when adding prandial insulin 1

Progression to Full Basal-Bolus

Add stepwise additional prandial injections (progressing from one to two to three meals) until glycemic targets are achieved. 1

Transitioning from IV to Subcutaneous Insulin

For ICU patients transitioning to subcutaneous therapy: 1

• Calculate TDD: Average hourly IV insulin rate × 24 hours (e.g., 1.5 units/hour = 36 units/day) 1
• Ensure stability: Glucose stable for 4-6 hours, hemodynamically stable, normal anion gap, stable nutrition plan 1
• Split dose: Proportion of basal versus prandial depends on insulin type and nutritional status 1

Critical Pitfalls to Avoid

Sliding Scale Insulin Alone

Never use sliding scale insulin (SSI) alone as the primary regimen—it is associated with clinically significant hyperglycemia and higher treatment failure rates (19% vs 0-2% with basal-bolus or basal-plus regimens). 1, 2

• SSI alone may be appropriate only for patients without diabetes who have mild stress hyperglycemia 1
• SSI should never be used alone in type 1 diabetes 1

Premixed Insulin in Hospital

Avoid premixed insulin (70/30) in the hospital setting—it carries an unacceptably high rate of iatrogenic hypoglycemia. 1

The 50-50 Rule Limitation

While the 50-50 basal-to-bolus split is a reasonable starting point, recognize that most patients with type 2 diabetes do not maintain this ratio long-term—over 75% of stable patients require <50% basal insulin, with significant individual variation over time. 3

Basal-Plus Alternative

For patients with mild hyperglycemia (glucose <200 mg/dL), decreased oral intake, or undergoing surgery, consider a basal-plus regimen instead: 1, 2

• Single dose of basal insulin (0.1-0.25 units/kg/day) 1
• Correctional rapid-acting insulin before meals or every 6 hours if NPO 1
• This approach achieved similar glycemic control to full basal-bolus with lower hypoglycemia risk in medical/surgical patients 2

Hypoglycemia Risk Management

Basal-bolus therapy carries 4-6 times higher hypoglycemia risk than SSI alone, with mild hypoglycemia occurring in 12-30% of patients in controlled settings. 1

When hypoglycemia occurs: 1

• Determine the cause
• If no clear reason identified, reduce the corresponding insulin dose by 10-20% 1

Insulin Selection

Prandial insulin options include: 1

• Rapid-acting analogs (lispro, aspart, glulisine) 1
• Ultra-rapid-acting analogs 1
• Short-acting human insulin 1
• Inhaled human insulin 1

Rapid-acting analogs should be given within 15 minutes before meals or immediately after meals. 4

Monitoring and Titration

Assess insulin adequacy at every visit, looking for signs of overbasalization: 1

• Basal dose >0.5 units/kg/day 1
• Elevated bedtime-to-morning glucose differential 1
• Elevated postprandial-to-preprandial differential 1
• Hypoglycemia (aware or unaware) 1
• High glucose variability 1

Use evidence-based titration algorithms, such as increasing basal insulin by 2 units every 3 days to reach fasting plasma glucose goal without hypoglycemia. 1