What are the target blood sugar levels for pregnant women?

Target Blood Sugar Levels for Pregnant Women

For pregnant women with diabetes, the recommended blood glucose targets are: fasting <95 mg/dL, one-hour postprandial <140 mg/dL, and two-hour postprandial <120 mg/dL. 1

Specific Target Ranges by Type of Diabetes

For Gestational Diabetes Mellitus (GDM)

• Fasting: <95 mg/dL (5.3 mmol/L) 1
• One-hour postprandial: <140 mg/dL (7.8 mmol/L) 1
• Two-hour postprandial: <120 mg/dL (6.7 mmol/L) 1

For Preexisting Type 1 or Type 2 Diabetes

• Fasting/premeal: 70-95 mg/dL (3.9-5.3 mmol/L) 1
• One-hour postprandial: 110-140 mg/dL (6.1-7.8 mmol/L) 1
• Two-hour postprandial: 100-120 mg/dL (5.6-6.7 mmol/L) 1
• Bedtime and overnight glucose: 60-99 mg/dL (3.3-5.4 mmol/L) 1

A1C Targets in Pregnancy

• Optimal target: <6% (42 mmol/mol) if achievable without significant hypoglycemia 1
• May be relaxed to <7% (53 mmol/mol) if necessary to prevent hypoglycemia 1
• A1C should be monitored more frequently during pregnancy (e.g., monthly) due to altered red blood cell kinetics 1

Monitoring Recommendations

Self-Monitoring of Blood Glucose

• Both fasting and postprandial monitoring are recommended for all pregnant women with diabetes 1
• Preprandial testing is also recommended for women using insulin pumps or basal-bolus therapy 1
• Postprandial monitoring is associated with better glycemic control and lower risk of preeclampsia 1, 2

Continuous Glucose Monitoring (CGM)

• For women with type 1 diabetes, CGM can help achieve better glycemic control 1
• Target range using CGM: 63-140 mg/dL (3.5-7.8 mmol/L) with goal >70% time in range 1
• Time below range (<63 mg/dL) should be <4% 1

Important Considerations and Pitfalls

Hypoglycemia Risk

• Targets should be achieved without causing significant hypoglycemia 1
• Early pregnancy is a time of enhanced insulin sensitivity with increased risk for hypoglycemia, particularly in women with type 1 diabetes 1
• If hypoglycemia is a concern, slightly higher targets may be considered: fasting <105 mg/dL, 1-h postprandial <155 mg/dL, and 2-h postprandial <130 mg/dL 1

Changing Insulin Requirements During Pregnancy

• First trimester: Often decreased insulin requirements 1
• Second and third trimesters: Insulin resistance increases exponentially, requiring frequent dose adjustments 1
• Insulin is the preferred medication for treating hyperglycemia in pregnancy 1, 3

Postprandial vs. Preprandial Monitoring

• Postprandial monitoring has been shown to be more effective than preprandial monitoring in achieving glycemic control and reducing adverse outcomes 2
• One-hour postbreakfast and two-hour postdinner measurements may capture more abnormal values than standard timing 4

Risks of Uncontrolled Diabetes in Pregnancy

• Fetal anomalies, macrosomia, and intrauterine fetal demise 1
• Preeclampsia and other maternal complications 1
• Neonatal hypoglycemia and hyperbilirubinemia 1
• Increased risk of obesity and type 2 diabetes in offspring later in life 1

Nutritional Considerations

• Consistent carbohydrate intake is important to match insulin administration 1
• Referral to a registered dietitian is recommended to establish an appropriate meal plan 1
• For women with GDM, lifestyle changes (diet and exercise) may be sufficient for glycemic control in many cases 1, 5

Remember that while these targets represent optimal control, they may need to be individualized based on the woman's specific situation, particularly for those with type 1 diabetes who may have difficulty achieving these targets without hypoglycemia 1.