What is the optimal insulin adjustment for a 28-week pregnant woman with type 1 diabetes, taking insulin Levemir (detemir) 20 units twice daily and insulin Lispro (lispro) with a carbohydrate ratio of 1:8, presenting with euglycemia (fasting glucose: 82 mg/dL), and postprandial hyperglycemia (1-hour post-breakfast glucose: 160 mg/dL, 1-hour post-lunch glucose: 110 mg/dL, 1-hour post-dinner glucose: 130 mg/dL)?

From the Guidelines

The best recommendation for SZ's insulin dosing is to intensify her carbohydrate ratio at breakfast to 1:6. Looking at her glucose values, her fasting blood glucose of 82 mg/dL is within target range for pregnancy, as recommended by the American Diabetes Association (ADA) in their 2025 standards of care in diabetes 1, but her 1-hour post-breakfast value of 160 mg/dL is elevated compared to her post-lunch and post-dinner values, which are well-controlled at 110 mg/dL and 130 mg/dL respectively. This pattern suggests that her current insulin-to-carbohydrate ratio of 1:8 at breakfast is not providing adequate coverage for her morning carbohydrate intake. By changing to 1:6 (1 unit of insulin lispro for every 6 grams of carbohydrates), she would receive more insulin with her breakfast, which should help lower her post-breakfast glucose spike. This targeted approach addresses the specific meal-related hyperglycemia without changing her basal insulin (levemir) doses, which appear to be maintaining appropriate fasting and between-meal glucose levels. During pregnancy, insulin requirements typically increase progressively, particularly after 20 weeks, due to increasing placental hormones that promote insulin resistance, so adjustments to insulin dosing are expected and necessary to maintain optimal glucose control, as supported by previous guidelines 1. Key considerations include:

• Fasting glucose targets: <95 mg/dL (<5.3 mmol/L) 1
• Postprandial glucose targets: <140 mg/dL (<7.8 mmol/L) for 1-hour postprandial or <120 mg/dL (<6.7 mmol/L) for 2-hour postprandial 1
• Importance of individualizing care to prevent hypoglycemia while achieving optimal glucose control 1

From the FDA Drug Label

DOSAGE AND ADMINISTRATION LEVEMIR can be administered once- or twice-daily. The dose of LEVEMIR should be adjusted according to blood glucose measurements. The patient's average glucose values are:

• Fasting: 82
• 1-hour post-breakfast: 160
• 1-hour post-lunch: 110
• 1-hour post-dinner: 130 Given that the 1-hour post-breakfast glucose value is 160, which is higher than the other post-meal values, it may be necessary to adjust the insulin dosing. Considering the patient's current insulin regimen, which includes insulin levemir 20 units twice daily and insulin lispro 1 unit for 8 grams of carbs at meals, the best recommendation would be to intensify the carb ratio at breakfast. However, since the provided drug labels do not directly address the specific question of how to adjust the insulin dosing for this patient, no conclusion can be drawn. Based on general clinical principles, the patient's glucose values suggest that the current insulin regimen may not be adequately controlling her post-breakfast glucose levels. Therefore, the most appropriate course of action would be to consult with the patient's healthcare provider to determine the best approach for adjusting her insulin dosing. Some possible considerations might include:
• Increasing the dose of insulin levemir
• Adjusting the carb ratio for insulin lispro at breakfast
• Monitoring the patient's glucose levels more closely to determine the best approach for adjusting her insulin dosing. It is essential to prioritize the patient's safety and adjust her insulin regimen under the guidance of a qualified healthcare provider. 2 3

From the Research

Insulin Dosing Recommendations

Based on the provided evidence, the following points can be considered for SZ's insulin dosing:

• The current insulin regimen consists of insulin levemir 20 units twice daily and insulin lispro 1 unit for 8 grams of carbs at meals.
• The average glucose values for the past week are: Fasting: 82,1-hour post-breakfast: 160,1-hour post-lunch: 110,1-hour post-dinner: 130.
• Studies have shown that the relationship between meal carbohydrate quantity and the insulin to carbohydrate ratio (ICR) required to maintain glycaemia is non-linear in people with type 1 diabetes 4.
• For meals with high carbohydrate content (≥150g), a strengthened ICR or dual wave bolusing may be beneficial 4.
• However, the provided studies do not directly address SZ's specific situation, and the optimal insulin dosing strategy may depend on individual factors.

Possible Adjustments

Considering the average glucose values, the following adjustments could be considered:

• Increasing the insulin levemir dose to 22 units twice daily may help improve fasting glucose control.
• Intensifying the carb ratio at breakfast to 1:6 may help reduce the 1-hour post-breakfast glucose value.
• De-intensifying the carb ratio at breakfast to 1:10 may not be necessary, given the current 1-hour post-breakfast glucose value.
• Increasing the levemir dose to 24 units in the evening and continuing 20 units in the morning may help improve glucose control during the night and early morning.

Limitations

It is essential to note that the provided studies do not directly address SZ's specific situation, and the optimal insulin dosing strategy may depend on individual factors, such as diet, physical activity, and other health conditions. Therefore, any adjustments to the insulin regimen should be made under the guidance of a healthcare professional, taking into account SZ's individual needs and response to therapy 5, 6, 7.