What is the equivalent dose of 15 units of insulin glargine when using a U‑100 insulin such as the FlexTouch pen?

15 Units of Insulin Glargine Equals 15 Units with U-100 FlexTouch

The dose is exactly the same: 15 units of insulin glargine is 15 units regardless of whether you use a U-100 vial, syringe, or FlexTouch pen. U-100 means there are 100 units of insulin per milliliter, and this concentration is standard across all U-100 insulin products 1.

Understanding U-100 Insulin Concentration

All U-100 insulins—whether insulin glargine (Lantus), insulin degludec, or any other basal insulin—contain the same concentration: 100 units per mL. This means:

• 15 units delivered from a U-100 FlexTouch pen = 15 units from any U-100 insulin delivery device
• The volume injected will be 0.15 mL (15 units ÷ 100 units/mL)
• No dose conversion or adjustment is needed when switching between U-100 delivery devices 1

Critical Distinction: U-100 vs. Concentrated Insulins

Important caveat: This 1:1 equivalence only applies when comparing U-100 products. If you were switching to concentrated insulin formulations, the dosing would differ:

• U-300 glargine is three times more concentrated (300 units/mL), so 15 units delivers the same biological effect but in one-third the volume 2, 3
• U-200 degludec is twice as concentrated (200 units/mL) 2, 3
• U-500 regular insulin is five times more concentrated and has different pharmacokinetics entirely 4

However, these concentrated formulations are typically reserved for patients requiring large insulin doses (>200 units/day for U-500, or those needing >0.5 units/kg/day) 4, 5.

FlexTouch Pen Advantages

The FlexTouch delivery system for U-100 insulin offers practical benefits without changing the dose:

• Delivers doses from 1-80 units in 1-unit increments 1
• Lower injection force required compared to other pens 6
• No push-button extension, improving ease of use 6
• Preferred by >90% of patients and healthcare professionals over other pen devices 6

Practical Dosing Guidance

When administering 15 units of U-100 insulin glargine via FlexTouch 1:

1. Attach a new sterile needle (never reuse)
2. Perform safety test (dial 2 units, press injection button until insulin appears)
3. Dial dose selector to 15 units
4. Inject subcutaneously into thigh, upper arm, or abdomen
5. Press injection button fully and hold while counting to 10
6. Remove needle and dispose properly

Rotate injection sites within the same anatomical area to prevent lipodystrophy (skin pitting or thickening) 1.

Common Pitfall to Avoid

Never use a syringe to withdraw insulin from a FlexTouch pen 1. The pen is designed as a complete delivery system. Using a syringe could result in dosing errors and pen damage. If you need to use a syringe, obtain insulin in vial form.