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

Basal Insulin Dose Adjustment for Elevated Fasting Glucose in Pregnancy

Increase the Lantus dose by 10–20% (6–12 units) immediately to a total of 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

Why This Fasting Glucose Requires Action

• A fasting glucose of 118 mg/dL exceeds the American Diabetes Association target of <95 mg/dL for pregnant women with pre-existing diabetes 2, 1, 3
• The American College of Obstetricians and Gynecologists sets an even stricter fasting target of <90 mg/dL 1
• Fasting hyperglycemia in pregnancy is directly associated with macrosomia, neonatal hypoglycemia, and other adverse perinatal outcomes 2

Specific Titration Algorithm

Initial adjustment:

• Raise the current 60-unit Lantus dose by 10–20%, which equals 6–12 units, bringing the total to 66–72 units 1
• This immediate increase addresses the current hyperglycemia without risking severe hypoglycemia 1

Ongoing titration:

• After the initial increase, continue adding 2–4 units every 2–3 days based on daily fasting glucose measurements 1
• The goal is to achieve fasting glucose consistently <95 mg/dL 2, 1, 3
• During the second and third trimesters, insulin resistance rises exponentially, often requiring weekly or bi-weekly dose escalations; total daily insulin may double or triple by week 36 1
• Insulin requirements typically increase at a rate of approximately 5% per week through week 36 1

Essential Monitoring Requirements

• Measure fasting glucose every morning and perform 4–6 blood glucose checks per day (fasting plus 1-hour or 2-hour postprandial after each meal) 2, 1
• Target 1-hour postprandial <140 mg/dL or 2-hour postprandial <120 mg/dL 2, 1, 3
• Check A1C monthly with a target <6% if achievable without significant hypoglycemia, or <7% if hypoglycemia risk is high 2, 1, 3
• A1C is a secondary metric in pregnancy because increased red blood cell turnover physiologically lowers A1C and may miss postprandial spikes that drive fetal macrosomia 1, 3

Critical Consideration: Prandial Insulin Coverage

• Basal insulin alone does not control postprandial glucose excursions 1
• If postprandial values exceed targets despite optimized basal insulin, add rapid-acting insulin (lispro or aspart) before each meal 1
• The American College of Obstetricians and Gynecologists recommends allocating a greater proportion of total daily insulin to prandial doses during pregnancy 1

Red-Flag Situations Requiring Urgent Evaluation

• A sudden, unexplained drop in insulin requirements may indicate placental insufficiency and warrants immediate obstetric assessment 1, 4
• First-trimester hypoglycemia risk is highest due to increased insulin sensitivity; comprehensive hypoglycemia education for the patient and family is mandatory before escalating insulin 1, 4

Multidisciplinary Referral

• Refer promptly to a specialized diabetes-and-pregnancy center for coordinated care involving maternal-fetal medicine, endocrinology, diabetes education, and nutrition 1, 4
• The complexity of insulin management in pregnancy—with rapidly changing insulin resistance and strict glycemic targets—requires team-based care for optimal maternal and fetal outcomes 1, 4