What is the recommended insulin regimen for pregnant women with diabetes?

Insulin Regimen for Pregnant Women with Diabetes

Insulin is the preferred agent for managing diabetes in pregnancy, with a basal-bolus regimen recommended where a small proportion of the total daily dose is given as basal insulin and a greater proportion as prandial insulin. 1, 2

Insulin Types and Administration

Recommended Insulin Types

• Human insulins are preferred as they do not cross the placenta 2
• All insulins are pregnancy category B except for glargine and glulisine, which are labeled C 1
• Ultra-short-acting analogs (insulin lispro or insulin aspart) are recommended for postprandial glucose control 3

Administration Methods

• Both multiple daily injections and insulin pump technology are appropriate delivery methods 1, 2
• For patients with severe insulin resistance, concentrated insulin formulations may be required 2, 4

Insulin Requirements Throughout Pregnancy

First Trimester

• Insulin requirements often decrease due to enhanced insulin sensitivity 1
• Higher risk of hypoglycemia during this period 1
• Total daily dose may decrease compared to pre-pregnancy requirements 1

Second Trimester

• Insulin resistance increases exponentially 1
• Weekly or biweekly increases in insulin dose are typically required 1
• Insulin requirements increase linearly at approximately 5% per week through week 36 1

Third Trimester

• Insulin requirements level off toward the end due to placental aging 1
• Total daily dose often doubles compared to pre-pregnancy requirements 1
• A rapid reduction in insulin requirements can indicate placental insufficiency 1

Postpartum

• Insulin requirements drop dramatically after delivery of the placenta 1
• Women become very insulin sensitive immediately postpartum 2

Glycemic Targets

Blood Glucose Targets

• Fasting: 70-95 mg/dL (3.9-5.3 mmol/L)
• One-hour postprandial: 110-140 mg/dL (6.1-7.8 mmol/L)
• Two-hour postprandial: 100-120 mg/dL (5.6-6.7 mmol/L) 1, 2

A1C Target

• <6% if achievable without significant hypoglycemia 1
• Monitor A1C more frequently (e.g., monthly) due to altered red blood cell kinetics during pregnancy 1

Insulin Dosing and Adjustment

Initial Dosing

• For type 1 diabetes: Continue insulin with adjustments based on trimester
• For type 2 diabetes: If newly starting insulin, begin with 0.7-1.0 units/kg/day divided as:
  • 40-50% as basal insulin
  • 50-60% as prandial insulin divided between meals 2

Dose Adjustments

• Adjust based on frequent blood glucose monitoring
• Increase doses weekly or biweekly in second trimester 1
• Higher proportion of total daily dose should be given as prandial insulin rather than basal insulin 1

Special Considerations

Insulin Administration Technique

• For cloudy insulins (NPH and premixed):
  • Gently roll and tip until crystals are resuspended
  • Roll horizontally between palms 10 times for 5 seconds
  • Tip 10 times for 10 seconds at room temperature
  • Avoid vigorous shaking as it produces bubbles affecting accurate dosing 1

Injection Sites During Pregnancy

• Abdomen is generally a safe site for insulin administration 1
• Use 4-mm pen needles due to thinning of abdominal fat from uterine expansion 1
• First trimester: No change in insulin site or technique needed
• Second trimester: Use entire abdomen with properly raised skinfolds
• Third trimester: Use lateral abdomen with properly raised skinfolds or consider thigh, upper arm, or buttock if patient is apprehensive 1

Hypoglycemia Management

• Increased risk of hypoglycemia in first trimester 1
• Altered counter-regulatory response may decrease hypoglycemia awareness 1
• Education for patients and family members about prevention, recognition, and treatment is essential 1, 2

Monitoring and Follow-up

• Frequent blood glucose monitoring is essential due to changing insulin requirements 2
• Pre- and postprandial monitoring is recommended 1
• Consider continuous glucose monitoring when available 2
• Due to complexity of insulin management, referral to a specialized center offering team-based care is recommended 1, 2

Additional Recommendations

• Prescribe low-dose aspirin 100-150 mg/day starting at 12-16 weeks gestation to reduce preeclampsia risk 1, 2
• Medical nutrition therapy with an individualized meal plan developed by a registered dietitian is recommended 2
• Monitor for diabetic ketoacidosis, which can occur at lower blood glucose levels during pregnancy 2

By following this comprehensive insulin regimen approach, optimal glycemic control can be achieved during pregnancy, minimizing risks to both mother and fetus while accommodating the physiological changes that occur throughout gestation.