How do you determine the basal insulin, prandial insulin, and correction insulin regimen for a patient?

Determining Insulin Regimens: Basal, Prandial, and Correction Components

For patients requiring insulin therapy, a basal-bolus regimen with basal, prandial, and correction components is the preferred treatment approach for optimal glycemic control. 1

Initial Basal Insulin Calculation

• Start basal insulin at 0.1-0.2 units/kg per day for most patients with type 2 diabetes 1
• For a 70kg patient, this would translate to approximately 7-14 units of basal insulin daily 1
• Choose a long-acting insulin analog (like insulin glargine) that can be administered once daily at the same time each day 2
• Set a fasting plasma glucose (FPG) target and follow an evidence-based titration algorithm 1
• Increase basal insulin by approximately 2 units every 3 days until reaching FPG target without hypoglycemia 1
• If hypoglycemia occurs, reduce the dose by 10-20% 1

Assessing Basal Insulin Adequacy

• Evaluate clinical signals for overbasalization (basal dose >0.5 units/kg/day, elevated bedtime-morning glucose differential, hypoglycemia, high variability) 1
• Consider adding a GLP-1 receptor agonist if A1C remains above target despite optimized basal insulin 1
• If basal insulin has been titrated to acceptable fasting glucose but A1C remains above target, advance to prandial insulin 3

Prandial (Mealtime) Insulin Initiation

• Start with one dose with the largest meal or meal with greatest postprandial glucose excursion 1
• Initial prandial insulin dose: 4 units per day or 10% of basal dose 1
• When adding prandial insulin, consider reducing basal insulin by 4 units or 10% to prevent hypoglycemia 1
• For patients requiring multiple daily injections, a full basal-bolus regimen divides total insulin as 50% basal and 50% prandial (split between meals) 3
• Titrate prandial insulin by 1-2 units or 10-15% twice weekly based on postprandial glucose readings 1

Correction Insulin Calculation

• Correction insulin uses the same rapid-acting insulin as prandial insulin 1
• Should not be used as the sole insulin strategy (sliding scale alone) as this approach is strongly discouraged 1
• Correction insulin should be added to scheduled insulin doses to address hyperglycemia that has already occurred 1
• For insulin-naive patients, a total daily insulin dose between 0.3 and 0.5 units/kg is recommended 1
• Lower correction doses should be used for patients at higher risk of hypoglycemia (older patients >65 years, those with renal failure, poor oral intake) 1

Special Considerations

• For patients with type 1 diabetes, a regimen with basal and correction components is necessary for all hospitalized patients, with prandial insulin added if eating 1
• When transitioning from IV insulin to subcutaneous insulin, administer subcutaneous basal insulin 2-4 hours before discontinuing IV insulin 1
• Convert to basal insulin at 60-80% of the daily infusion dose when transitioning from IV to subcutaneous insulin 1
• For a patient receiving an average of 1.5 units per hour IV insulin, the estimated daily subcutaneous dose would correspond to 36 units/24 hours 1
• Monitor for hypoglycemia (<70 mg/dL) and adjust treatment regimen accordingly 1

Common Pitfalls to Avoid

• Avoid sole use of sliding scale insulin (correction only), which is associated with poor glycemic control 1
• Avoid premixed insulin formulations in the hospital setting due to increased hypoglycemia risk 1
• Avoid rapid adjustments in insulin dosing without considering patterns over several days 1
• Be vigilant for hypoglycemia, especially if medication doses change or with irregular meal patterns 3
• Recognize that basal insulin alone is often insufficient for patients with significant postprandial hyperglycemia 4

By following these guidelines for calculating and adjusting basal, prandial, and correction insulin components, clinicians can optimize glycemic control while minimizing the risk of hypoglycemia in patients requiring insulin therapy.