What is the recommended insulin management strategy for a 37-year-old female with overt Diabetes Mellitus (DM) undergoing a repeat Cesarean Section (C-section), currently on insulin 70/30 (Novolin 70/30, NPH/Regular insulin) - 28 units pre-breakfast and 16 units pre-supper?

Perioperative Insulin Management for Cesarean Section in Overt Diabetes

For a 37-year-old woman with overt diabetes on insulin 70/30 undergoing repeat cesarean section, transition immediately postoperatively from her premixed insulin to intravenous insulin infusion targeting blood glucose 100-180 mg/dL, then convert to a basal-bolus subcutaneous regimen before discharge using the total 24-hour IV insulin dose as your calculation basis. 1

Immediate Perioperative Management

Day of Surgery

• Schedule the cesarean section early in the morning to minimize fasting time and reduce the risk of dehydration, acidosis, and ketosis 2
• Hold the morning dose of insulin 70/30 on the day of surgery
• Initiate IV insulin infusion intraoperatively or immediately postoperatively, targeting blood glucose between 100-180 mg/dL 1, 2
• Monitor capillary blood glucose every 30 minutes from induction of anesthesia until fully conscious, then every 1-2 hours while on IV insulin 2, 1

Critical Postoperative Consideration

After delivery, maternal insulin requirements drop precipitously, creating significant hypoglycemia risk if pre-pregnancy insulin doses are continued 2. This physiologic change is further amplified during breastfeeding 2.

Transition from IV to Subcutaneous Insulin

Timing and Calculation

When the patient resumes oral intake and blood glucose stabilizes ≤180 mg/dL for at least 24 hours 1:

1. Calculate total IV insulin administered over the last 24 hours when glucose was stable 1, 3
2. Basal insulin dose = 50% of the 24-hour IV insulin total, given as once-daily long-acting insulin (glargine) 1, 3
3. Prandial insulin dose = remaining 50% divided by 3 meals, using ultra-rapid insulin analogue before each meal 1, 3

Critical Timing to Prevent Ketoacidosis

Administer the subcutaneous basal insulin 2 hours before discontinuing the IV insulin infusion 1, 3. This 2-hour overlap is mandatory to prevent rebound hyperglycemia and diabetic ketoacidosis 1, 3. Never discontinue IV insulin before giving subcutaneous basal insulin—this creates a dangerous coverage gap 1.

Ongoing Monitoring Protocol

Glucose Monitoring Frequency

• Before each meal and at bedtime once eating 1, 4
• Every 1-2 hours while NPO and receiving glucose-containing infusions 4
• Every 15 minutes after hypoglycemia treatment until glucose >100 mg/dL 4

Management of Glycemic Excursions

For hypoglycemia:

• Blood glucose <60 mg/dL: Give 15-20 grams IV dextrose immediately, even without symptoms 4, 3
• Blood glucose 60-70 mg/dL with symptoms: Give 15-20 grams IV dextrose 4

For hyperglycemia (pre-meal glucose >300 mg/dL):

• Check for ketosis immediately 1, 4
• If ketonuria = 0 or ketonemia <0.5 mmol/L: Give 6 units ultra-rapid insulin subcutaneously, recheck glucose in 3 hours 1, 2
• If ketonuria 1+ or ketonemia 0.5-1.5 mmol/L: Give 6 units ultra-rapid insulin subcutaneously, recheck glucose and ketosis in 3 hours 2
• If ketonuria 2+ or ketonemia ≥1.5 mmol/L: Transfer to ICU for IV insulin infusion therapy 2

Discharge Planning

Insulin Regimen at Discharge

Continue the basal-bolus regimen established in hospital at the doses used during hospitalization 1, 2. Do not automatically resume the pre-pregnancy insulin 70/30 regimen, as postpartum insulin requirements are substantially lower 2.

Follow-up Scheduling Based on Glycemic Control

The discharge plan depends on HbA1c level (if available) or inpatient glycemic control 2:

• HbA1c <8% or stable glucose control: Schedule follow-up with primary physician within one month 2, 1
• HbA1c 8-9%: Arrange consultation with diabetologist for treatment intensification 2
• HbA1c >9% or unstable glucose levels >200 mg/dL (11 mmol/L): Request diabetologist consultation before discharge for possible hospitalization in specialized service 2, 1, 3

Patient Education Requirements

Provide education on 2:

• Recognition and management of hypoglycemia (especially critical during breastfeeding) 2
• Self-monitoring of blood glucose
• Insulin injection techniques for the new basal-bolus regimen
• Dietary modifications to support breastfeeding 2

Common Pitfalls to Avoid

1. Never resume pre-pregnancy insulin doses immediately postpartum—insulin requirements drop dramatically after delivery and during breastfeeding 2
2. Never use sliding-scale insulin alone as the primary regimen—this approach increases hypoglycemia risk while providing inadequate basal coverage 4, 3
3. Never discontinue IV insulin without first administering subcutaneous basal insulin—this creates a dangerous gap that can precipitate diabetic ketoacidosis 1, 3
4. Do not delay basal insulin administration—it must be given 2 hours before stopping IV insulin 1, 3

Special Considerations for Breastfeeding

Monitor closely for hypoglycemia during breastfeeding, as this further reduces insulin requirements 2. The patient should have glucose tablets or juice readily available during nursing sessions.