What volume of insulin glargine (Lantus) is required for a 90-day supply, given a dosing regimen of 40 units twice daily (BID) and a concentration of 100 units per 3 milliliters (mL) pen?

From the Research

To provide a 90-day supply of glargine insulin for a patient injecting 40 units twice daily (BID), you would need 72 mL of insulin. This calculation is based on the patient using 80 units total per day (40 units BID), which equals 80 units × 90 days = 7,200 units total for the 90-day period. Since each 3 mL pen contains 100 units/mL (300 units total per pen), you would need 7,200 units ÷ 300 units per pen = 24 pens. This equals 24 pens × 3 mL = 72 mL of insulin. The most recent study 1 supports the use of twice-daily dosing of insulin glargine, but it does not affect the calculation of the required volume of insulin. Key points to consider when calculating the required volume of insulin include:

• The patient's daily insulin dose (80 units)
• The duration of the supply (90 days)
• The concentration of insulin glargine (100 units/mL)
• The volume of each pen (3 mL) The calculation is straightforward and is not affected by the patient's diabetes type or other factors, as shown in previous studies 2, 3, 4, 5.