What is the recommended insulin dosage for a pregnant female with diabetes?

Insulin Dosage for Pregnant Females with Diabetes

Insulin is the preferred medication for managing both type 1 and type 2 diabetes in pregnancy, with dosing requiring frequent titration as requirements typically double to triple by the third trimester. 1, 2

Initial Insulin Regimen Selection

Either multiple daily injections (basal-bolus regimen) or continuous subcutaneous insulin infusion (insulin pump) can be used, as neither has been shown to be superior. 1, 2 The choice should be based on patient preference and local expertise. 3

• Human insulin preparations that do not cross the placenta are preferred 2
• Insulins studied in randomized controlled trials should be prioritized over those with only observational data 2

Insulin Dose Adjustments Throughout Pregnancy

First Trimester (Weeks 0-13)

• Insulin requirements often decrease due to enhanced insulin sensitivity, significantly increasing hypoglycemia risk 1, 2, 4
• Many women with type 1 diabetes will have lower insulin requirements during this period 1
• Close monitoring is essential, with dose reductions as needed to prevent hypoglycemia 4

Second and Third Trimesters (Weeks 14-40)

• Insulin resistance increases exponentially starting around 16 weeks of gestation 1, 2
• Requirements typically increase by approximately 5% per week through week 36 4
• By late gestation, total daily insulin requirements typically double to triple compared to pre-pregnancy doses 2, 5
• Regular evaluation and dose adjustment every 2-3 weeks is necessary 2

Specific Dosing Patterns by Diabetes Type

Type 1 Diabetes:

• Insulin requirements follow a triphasic pattern with progressive increases through pregnancy 5
• Women require careful monitoring due to higher hypoglycemia risk and altered counterregulatory responses 2, 4

Type 2 Diabetes:

• Glycemic control is often easier to achieve than in type 1 diabetes, but may require much higher absolute insulin doses 1, 2
• Some patients may require concentrated insulin formulations (such as U-500 insulin) due to severe insulin resistance 2, 6
• Type 2 diabetes patients require significantly higher doses than type 1 patients during each trimester 5

Target Glucose Levels for Dose Titration

Insulin doses should be adjusted to achieve the following targets: 1, 2, 4

• Fasting glucose: 70-95 mg/dL (< 5.3 mmol/L)
• One-hour postprandial: 110-140 mg/dL (< 7.8 mmol/L)
• Two-hour postprandial: 100-120 mg/dL (< 6.7 mmol/L)

Monitoring Strategy

• Daily monitoring of fasting and postprandial blood glucose 4-6 times daily is essential for insulin dose adjustments 2, 4
• Preprandial testing is recommended when using insulin pumps or basal-bolus therapy to adjust premeal rapid-acting insulin dosage 1
• Continuous glucose monitoring can help identify trends and prevent severe hypoglycemia, but should not replace self-monitoring for dose adjustments 1, 2, 4

Critical Warning Signs

A rapid reduction in insulin requirements, especially in the second or third trimester, may indicate placental insufficiency and requires immediate medical evaluation. 2, 4 This is a medical emergency requiring:

• Urgent fetal assessment including non-stress testing and ultrasound 4
• Evaluation for preeclampsia (blood pressure, proteinuria) 4
• Increased frequency of fetal monitoring 4

Post-Delivery Insulin Management

Insulin resistance drops precipitously after placental delivery, requiring immediate dose reduction. 2, 4

• Resume basal-bolus insulin at either 80% of pre-pregnancy doses or 50% of end-of-pregnancy doses 2
• Close monitoring is essential in the immediate postpartum period 1

Critical Pitfalls to Avoid

• Never stop basal insulin in type 1 diabetes patients, as this carries high risk of diabetic ketoacidosis (DKA) 4
• Pregnancy is a ketogenic state, and women with type 1 diabetes are at risk for DKA at lower blood glucose levels than when not pregnant 1, 2, 4
• Women should be prescribed ketone strips and receive education on DKA prevention and detection 1, 4
• Hypoglycemia awareness may be decreased during pregnancy, requiring education for patients and family members about prevention, recognition, and treatment 1, 2, 4

Specialized Care Recommendation

Due to the complexity of insulin management in pregnancy, referral to a specialized center offering team-based care (including maternal-fetal medicine specialist, endocrinologist, dietitian, nurse, and social worker) is recommended. 1, 2