Insulin pump dosing across gestation in women with well-controlled type 1 diabetes mellitus.

OBJECTIVE: We hypothesized that bolus and basal insulin doses in women with type 1 diabetes mellitus who use insulin pumps would increase 2-fold to maintain hemoglobin A1c <6.5% across gestation. STUDY DESIGN: This was a retrospective study of 9 women with type 1 diabetes mellitus with preconceptional hemoglobin A1c ≤ 7.4% using insulin pumps. The primary outcome was absolute and percentage change of basal and bolus insulin from preconception to delivery. RESULTS: Total daily dose of insulin increased from 33.3 ± 7.8 U/d before conception to 93.5 ± 27.9 U/d at delivery. Basal rates rose modestly (50% increase, from 16.2 ± 6.5 U/d to 24.0 ± 9 U/d); bolus insulin doses quadrupled from 17.1 ± 6.1 U/d to 69.5 ± 29.6 U/d (P = .0001). Bolus insulin increased from approximately 50% of total daily dose of insulin before conception to 75% of total daily dose of insulin at 36 weeks' gestation. CONCLUSION: In well-controlled type 1 diabetes mellitus, insulin requirements increased 3-fold from before conception to 36 weeks' gestation. Most of this requirement was attributed to an increase in bolus rates that are required for control with meals.