What are the target blood sugar levels in mg/dl for pregnant women with diabetes?

Target Blood Sugar Levels in Pregnancy

For pregnant women with diabetes, target fasting blood glucose <95 mg/dL and either 1-hour postprandial <140 mg/dL or 2-hour postprandial <120 mg/dL to minimize risks of macrosomia, neonatal complications, and maternal morbidity. 1

Specific Targets by Diabetes Type

Gestational Diabetes Mellitus (GDM)

For women with GDM not on insulin:

• Fasting glucose: <95 mg/dL 1
• 1-hour postprandial: <140 mg/dL 1
• 2-hour postprandial: <120 mg/dL 1

For women with GDM treated with insulin:

• Fasting glucose: 70-95 mg/dL 1
• 1-hour postprandial: 110-140 mg/dL 1
• 2-hour postprandial: 100-120 mg/dL 1

Preexisting Type 1 or Type 2 Diabetes

For women with preexisting diabetes:

• Fasting/premeal glucose: 70-95 mg/dL 1
• 1-hour postprandial: 110-140 mg/dL 1
• 2-hour postprandial: 100-120 mg/dL 1

The lower limit of 70 mg/dL does not apply to women with type 2 diabetes managed by nutrition alone. 1

A1C Targets

Target A1C <6% if achievable without significant hypoglycemia; may relax to <7% if necessary to prevent hypoglycemia. 1

• A1C <6% is associated with the lowest risk of large-for-gestational-age infants, preterm delivery, and preeclampsia in the second and third trimesters 1
• A1C should be monitored monthly during pregnancy due to increased red blood cell turnover that physiologically lowers A1C 1
• A1C serves as a secondary measure after self-monitoring of blood glucose, as it may not capture postprandial hyperglycemia that drives macrosomia 1

Continuous Glucose Monitoring Targets

For women using CGM (particularly those with type 1 diabetes):

• Target sensor glucose range: 63-140 mg/dL 1
• Time in range goal: >70% 1
• Time below range <63 mg/dL (level 1): goal <4% 1
• Time below range <54 mg/dL (level 2): goal <1% 1

CGM has been shown to improve maternal glucose time in range and reduce time above range in pregnant women with type 1 diabetes. 1

Monitoring Strategy

Perform fasting, preprandial, and postprandial blood glucose monitoring to achieve optimal glucose levels. 1

• Self-monitoring should occur at least 4-7 times daily, including fasting, preprandially, and 1-2 hours postprandially 2
• Postprandial monitoring is superior to preprandial monitoring alone, as it improves glycemic control and reduces neonatal hypoglycemia, macrosomia, and cesarean delivery rates 3
• For women on insulin pumps or basal-bolus therapy, preprandial testing is essential for dose adjustments 2

Critical Pitfalls to Avoid

Early pregnancy presents enhanced insulin sensitivity with significantly increased hypoglycemia risk; targets must be achieved without causing significant hypoglycemia. 1

• Hypoglycemia in pregnancy may increase the risk of low birth weight 1
• Insulin requirements typically decrease in the first trimester, then increase exponentially during the second trimester and plateau in the third trimester 1
• Fear of hypoglycemia leading to inadequate control increases fetal complication risks 4

Do not rely solely on A1C for management decisions during pregnancy. 1

• A1C represents an integrated average and may miss physiologically relevant postprandial hyperglycemia that drives macrosomia 1
• Red blood cell turnover increases during pregnancy, causing A1C to fall even with stable glucose control 1

Evidence Supporting Tighter Targets

A fasting glucose target of <90 mg/dL is most strongly associated with reduced risk of macrosomia in women with gestational diabetes. 5

• Meta-analysis evidence shows this target reduces macrosomia risk by approximately 47% (OR 0.53,95% CI 0.31-0.90) 5
• Postprandial glucose control is particularly important, as postprandial hyperglycemia drives fetal macrosomia more than fasting hyperglycemia 1, 3