Insulin glargine U100 and U300: What is the difference?

If the box says 300 units, look for the volume

One Lantus prefilled pen listed by Sanofi China contains 300 units in 3 mL, or 100 units per mL (U100). A Chinese Toujeo pen contains 450 units in 1.5 mL, or 300 units per mL (U300). If “300 units” appears next to “3 mL,” it may mean the total amount in the pen. “300 units/mL” is a concentration.

Chinese Lantus prefilled pen — Concentration per mL: 100 units/mL. Volume and total per pen: 3 mL, 300 units.

Chinese Toujeo prefilled pen — Concentration per mL: 300 units/mL. Volume and total per pen: 1.5 mL, 450 units.

US Toujeo Max SoloStar — Concentration per mL: 300 units/mL. Volume and total per pen: 3 mL, 900 units.

These are examples from prescribing information or manufacturer packaging. Your doctor determines the prescribed dose for each injection.

Two U300 pens can work differently

The US Toujeo label lists a 1.5 mL SoloStar and a 3 mL Max SoloStar. Both are U300, but their dose counters advance in 1-unit and 2-unit increments respectively. If you take a US Max SoloStar to China, photograph the full model name so the team can tell which pen you use.

Lantus is also listed in prefilled pens and cartridges. If your old prescription only says Lantus or insulin glargine, show photos of the box and pen to help the team check the generic name, concentration, device and local availability.

Concentration and the dose counter

Concentration describes the liquid. The counter displays the number of units dialled on that pen. Both strengths contain insulin glargine, but their effects in the body differ and a clinician must supervise a switch. Do not use the concentration ratio to calculate your own dose or withdraw insulin from a U300 pen with a syringe.

The US and Chinese labels cover different groups

The Chinese Toujeo leaflet cited here lists adults with type 2 diabetes requiring insulin. The US label covers adults and children aged 6 and older with diabetes. Before travelling, give the receiving doctor the diagnosis, age, original prescription and exact pen model if the medicine is for a child or an adult with type 1 diabetes. This comparison is limited to the two label versions cited.

What to bring when continuing treatment in China

Bring the prescription, photos of the side of the box and the pen label, and recent glucose records. Keep U100 or U300 and SoloStar or Max SoloStar legible. If you recently had low blood sugar, tell the doctor when it happened and what you measured.

If the hospital cannot supply your original presentation, ask the team to specify the product and device in writing. Ask a pharmacist to show you how to read the counter if needed. Ask the doctor what glucose readings to record before follow-up and whom to contact if a reading is abnormal. See What to do if your usual medicine is unavailable in China.