Objective: To reevaluate current formulas for determining the total basal insulin dosage (TBD), insulin to carbohydrate ratio (ICR), and correction factor (CF) from weight or total daily dosage (TDD) in pump-treated patients with type 1 diabetes mellitus.
Methods: From a post hoc analysis of data from 4 previously published studies, subjects who met the inclusion criteria were selected. No subject was duplicated. For all studies, the basal glucose target was to have fewer than 20%of glucose readings greater than 170 mg/dL and to have 10% or fewer glucose readings less than 70 mg/dL. Bolus insulin was adjusted to achieve a 2- to 4-hour postbolus glucose value within 20% of the premeal glucose (ICR) or 80 to 120 mg/dL from premeal hyperglycemia (CF). In the first 2 studies, dosing titration by CGM was performed from 72-hour CGM tracings every week to every 6 weeks. In the other 2 studies, 24- to 72-hour CGM downloads and insulin adjustments were done each weekday.
Results: Of 101 participants, 61 (59% women) met the inclusion criteria. Estimation formulas could be rounded to the following: TBD = 0.2 x weight (kg) or 0.4 x TDD; ICR = 300 / TDD; and CF = 1500 / TDD. In particular the relationship between all 3 dosing factors could be represented as 100 / TBD = ICR = CF / 4.5.
Conclusions: These results suggest that current formulas give a higher estimate for TBD and a lower estimate for the bolus dose.