Insulin Dosing for TPN in a Type 2 Diabetes Patient
For a 57-year-old male with type 2 diabetes starting TPN with 210 grams of dextrose, add 21 units of regular insulin to the TPN solution (1 unit per 10g of dextrose) while continuing his daily Lantus dose of 23 units.
Initial Insulin Calculation for TPN
- The American College of Clinical Endocrinologists recommends adding regular human insulin to the TPN solution at an initial dose of 1 unit per 10g of carbohydrate 1
- For this patient with 210g of dextrose in TPN, the initial regular insulin dose would be 21 units added directly to the TPN solution 2
- Continue the patient's basal insulin (Lantus 23 units daily) to maintain background glycemic control 2
Rationale for This Approach
- Regular insulin is the appropriate insulin formulation to add directly to TPN solutions due to its compatibility with parenteral nutrition components 1
- The 1:10 ratio (1 unit of insulin per 10g of carbohydrate) is the standard starting point for insulin dosing in TPN for patients with diabetes 2, 1
- Maintaining the patient's basal insulin (Lantus) helps provide consistent background insulin coverage while the TPN-added insulin addresses the carbohydrate load from the nutrition 2
Monitoring and Adjustment Protocol
- Monitor blood glucose every 6 hours initially 2
- If more than 20 units of correctional insulin are required in a 24-hour period, increase the insulin dose in the TPN solution 2, 1
- Consider the patient's weight (100kg) and BMI (30), which suggest insulin resistance, potentially requiring higher insulin doses over time 2
Important Considerations
- Patients with type 2 diabetes generally require higher insulin doses (approximately 1 unit/kg) compared to those with type 1 diabetes 2
- Be aware that insulin can adsorb to polyvinylchloride (PVC) surfaces of fluid containers and infusion sets, potentially reducing the amount of insulin that reaches the patient 3
- If TPN is interrupted, immediately start a 10% dextrose infusion to prevent hypoglycemia 1