In a pregnant patient with a fasting plasma glucose of 118 mg/dL on Lantus (insulin glargine) 60 units, how many units should the Lantus dose be increased?

Insulin Dose Adjustment for Elevated Fasting Glucose in Pregnancy

Increase the Lantus dose by 10-20% (6-12 units) immediately to 66-72 units, then continue titrating upward by 2-4 units every 2-3 days until fasting glucose consistently falls below 95 mg/dL. 1

Rationale for Immediate Dose Escalation

Your patient's fasting glucose of 118 mg/dL substantially exceeds the American Diabetes Association's target of 70-95 mg/dL for pregnant women with diabetes 2, 1. This degree of hyperglycemia requires prompt intervention because:

• Fasting hyperglycemia is the strongest predictor of macrosomia and adverse pregnancy outcomes in gestational diabetes 3
• The current dose of 60 units is clearly insufficient given the marked fasting elevation
• Insulin resistance increases exponentially during the second and third trimesters, with requirements rising approximately 5% per week through week 36 1, 4
• Total daily insulin typically doubles to triples by late pregnancy compared to early pregnancy or pre-pregnancy doses 2, 1, 4

Specific Titration Algorithm

Initial Adjustment

• Add 6-12 units immediately (10-20% increase from current 60 units) 1
• This brings the dose to 66-72 units as a starting point

Ongoing Titration Strategy

• Increase by 2-4 units every 2-3 days based on daily fasting glucose measurements 1
• Continue escalating until fasting glucose is consistently <95 mg/dL 2, 1
• Do not hesitate to make frequent adjustments—weekly or biweekly dose escalations are often necessary during the second and third trimesters 1, 5

Alternative Aggressive Approach

A recent study demonstrated that patient-led daily titration using 4-unit increases after every fasting glucose ≥90 mg/dL resulted in significantly better glycemic control (mean fasting 83 vs 92 mg/dL), lower birthweight z-scores, and no increase in hypoglycemia 3. This approach may be considered if the patient is reliable and has adequate diabetes education.

Critical Monitoring Requirements

• Daily fasting glucose measurements are mandatory to guide dose adjustments 1, 4
• Perform 4-6 blood glucose checks daily: fasting, pre-meals, and either 1-hour postprandial (<140 mg/dL) or 2-hour postprandial (<120 mg/dL) 2, 1, 4
• Monthly A1C monitoring with a target <6% (or <7% if hypoglycemia risk is high) 2, 1
• Remember that A1C is a secondary metric in pregnancy because it may miss postprandial spikes that drive fetal macrosomia 1

Prandial Insulin Considerations

Basal insulin alone will not control postprandial glucose excursions. 1 If postprandial values exceed targets despite adequate basal coverage:

• Add rapid-acting insulin (lispro or aspart) before each meal 1
• The American College of Obstetricians and Gynecologists recommends that a greater proportion of total daily insulin should be allocated to prandial doses rather than basal insulin during pregnancy 1, 4

Critical Safety Warnings

Red-Flag Situations

• A sudden unexplained drop in insulin requirements may indicate placental insufficiency and warrants immediate obstetric evaluation 2, 1, 5, 4
• First-trimester hypoglycemia risk is highest due to enhanced insulin sensitivity; comprehensive hypoglycemia education for patient and family is essential 1, 5, 4

Hypoglycemia Prevention

• Provide education on prevention, recognition, and treatment of hypoglycemia before escalating doses 1, 5, 4
• Pregnancy attenuates counter-regulatory hormone responses, reducing hypoglycemia awareness 1
• Diabetic ketoacidosis can develop at lower glucose levels (<200 mg/dL) in pregnancy and carries high risk of stillbirth 1

Specialized Care Recommendation

Referral to a specialized diabetes-and-pregnancy center is strongly recommended due to the complexity of insulin management during pregnancy 1, 5, 4. These centers provide coordinated multidisciplinary care involving maternal-fetal medicine, endocrinology, diabetes education, and nutrition.

Common Pitfalls to Avoid

• Do not under-dose out of fear of hypoglycemia—the fasting glucose of 118 mg/dL indicates substantial insulin deficiency that requires aggressive correction
• Do not wait more than 2-3 days between dose adjustments when fasting glucose remains elevated 1
• Do not rely solely on basal insulin—assess postprandial values and add prandial coverage as needed 1
• Do not ignore the exponential rise in insulin resistance—expect to make frequent, substantial dose increases throughout the second and third trimesters 2, 1, 4