Objective: To evaluate the mathematical relationships between dosing factors in type 1 diabetic patients using multiple daily injections.
Methods: In this single-center, prospective study in type 1 diabetic patients, the basal continuous glucose monitoring glucose target was less than 130 mg/dL with fewer than 10% of 24-hour readings at less than 70 mg/dL. Basal glucose for the 4-hour meal periods was obtained from once-daily serial meal omissions. On an isocaloric, 50% carbohydrate, fixed diet, the insulin to carbohydrate ratio was adjusted to achieve a 2- to 4-hour postbolus glucose value within ±20% of premeal glucose. For determining dosing formulas, the slope of the linear regression line comparing the variables of weight, total daily dose (TDD), total basal dose (TBD), insulin-to-carbohydrate ratio (ICR), and correction factor (CF) was determined.
Results: Forty-nine patients were included. Titrating insulin glargine to the morning glucose led to hypoglycemia during the rest of the day (2 PM to 4 AM). Therefore the basal glucose target was the nondawn phenomenon portion of the day. The resulting estimation formulas could be rounded to the following: TBD = 0.2 x weight (kg) | TBD = 0.33 x TDD | 90/TBD = ICR = CF/4.5.
Conclusions: Smaller insulin glargine doses to achieve control are in contrast to those much larger doses reported in clinical trials in multiple daily injection-treated type 1 diabetes in which the morning fasting glucose is the basal insulin target.