How many Insulin Glargine 100 units/mL pens are needed for a 30-day supply at 40 units/day?

Insulin Glargine 100 units/mL Pen Dispensing Calculation

For a 30-day supply at 40 units per day, dispense 4 pens (3 mL each) of Insulin Glargine 100 units/mL. 1

Calculation Breakdown

Total insulin needed for 30 days:

• 40 units/day × 30 days = 1,200 units total 1

Insulin content per pen:

• Each Insulin Glargine SoloStar prefilled pen contains 3 mL 1
• At 100 units/mL concentration, each pen contains 300 units (3 mL × 100 units/mL) 1

Number of pens required:

• 1,200 units ÷ 300 units per pen = 4 pens 1

Practical Dispensing Considerations

Standard dispensing practice:

• Dispense 4 pens for a 30-day supply at 40 units daily 1
• Each pen is single-patient-use only and must never be shared between patients, even if the needle is changed 1

Refill recommendations:

• Provide refills for ongoing therapy, as this 40-unit daily dose falls within typical maintenance ranges for type 2 diabetes (generally around 1 unit/kg) 2
• The American Diabetes Association recommends reassessing and modifying insulin therapy every 3-6 months to avoid therapeutic inertia 3

Clinical Context for This Dose

Dose appropriateness:

• The 40-unit daily dose is reasonable for basal insulin therapy in type 2 diabetes 4, 2
• For a patient weighing approximately 40-80 kg, this represents 0.5-1.0 units/kg/day, which is within typical ranges 4
• When basal insulin exceeds 0.5 units/kg/day and approaches 1.0 units/kg/day, consider adding prandial insulin or GLP-1 receptor agonist rather than continuing to escalate basal insulin alone 3, 4

Administration instructions:

• Administer subcutaneously once daily at bedtime at the same time every day 1
• Rotate injection sites within the same region (abdominal area, thigh, or deltoid) to reduce risk of lipodystrophy 1
• Do not dilute or mix with any other insulin or solution 1