Can a post-operative patient with a Hemoglobin A1c (HbA1c) of 11, currently on a sliding scale insulin regimen and total parenteral nutrition (TPN), be started on long-acting insulin glargine (insulin glargine)?

Starting Long-Acting Insulin Glargine in a Post-Operative Patient on TPN

Yes, you should start long-acting insulin glargine in this post-operative patient with HbA1c of 11% and blood glucose of 230 mg/dL on TPN, as sliding scale insulin alone is inadequate and strongly discouraged for managing hyperglycemia in hospitalized patients. 1

Why Sliding Scale Alone is Insufficient

• Sliding scale insulin (SSI) as monotherapy is not effective and should not be used, especially because it excludes a basal insulin component from therapy 2
• The basal-bolus regimen significantly improves glycemic control compared to sliding scale alone, with mean glucose of 145 mg/dL versus 172 mg/dL, and reduces composite complications from 24.3% to 8.6% (OR 3.39, P=0.003) 1
• Your patient's HbA1c of 11% indicates severely uncontrolled diabetes requiring a basal-bolus insulin regimen 3

Specific Insulin Regimen for TPN Patients

Initiate a basal-bolus insulin regimen with the following approach:

Basal Insulin (Glargine) Dosing:

• Start glargine at 0.3-0.4 IU/kg/day for patients with diabetes receiving TPN 4
• Administer once daily at the same time each day 5
• For a patient with HbA1c >9% and blood glucose >11 mmol/L (200 mg/dL), maintain the basal-bolus scheme rather than attempting to simplify therapy 3

Prandial/Correction Insulin:

• Continue correction doses with ultra-rapid insulin analogue (aspart, lispro, or glulisine) for blood glucose excursions 2
• For pre-meal blood glucose >16.5 mmol/L (300 mg/dL), administer 6 units of ultra-rapid insulin subcutaneously and check for ketosis 6

TPN-Specific Considerations

Important nuances for patients on TPN:

• Insulin can be safely administered subcutaneously alongside TPN rather than added directly to the TPN bag, which has variable bioavailability (44-95%) and makes dose adjustments difficult 7
• The basal-correction insulin regimen is an effective alternative method for managing hyperglycemia in non-critically ill surgical patients on TPN 4
• Target blood glucose should be maintained between 100-180 mg/dL (5.6-10.0 mmol/L) 1, 6

Monitoring Protocol

Implement the following glucose monitoring schedule:

• Check capillary blood glucose every 4-6 hours while on continuous TPN 8
• Monitor more frequently (every 1-2 hours) if blood glucose is unstable or >180 mg/dL 1, 6
• Adjust insulin doses daily based on glucose patterns 6

Critical Pitfalls to Avoid

• Never rely on sliding scale insulin alone as the primary regimen in a patient with HbA1c of 11% 1, 2
• Do not delay starting basal insulin—begin immediately given the current hyperglycemia and severely elevated HbA1c 1
• Avoid administering glargine intravenously or mixing it with TPN solution 5
• Do not inject into areas of lipodystrophy; rotate injection sites within the same region (abdominal area, thigh, or deltoid) 5

Hypoglycemia Management

Be prepared to treat hypoglycemia:

• For blood glucose <60 mg/dL, administer 15-20 grams IV dextrose immediately, even without symptoms 1, 6
• Monitor glucose every 15 minutes after hypoglycemia correction until glucose >100 mg/dL 1

Expected Insulin Requirements

• Studies show insulin total daily dose (TDD) averages 0.5 ± 0.3 U/kg/day in patients with diabetes on TPN 4
• Hypoglycemic events occur but are not increased with basal-correction regimens compared to other approaches 4

Consultation Recommendations

Given the HbA1c >9% and blood glucose >11 mmol/L (200 mg/dL):

• Request diabetologist consultation before discharge for possible hospitalization in a specialized service or intensive outpatient management 3
• This patient requires ongoing diabetes education and close follow-up given the severity of hyperglycemia 3, 6