Concentrated Insulin: U-500, U-300 and U-200 Explained
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[Glossary · Mixing and measuring]

Concentrated insulin

Also called U-500 insulin, U-300 insulin, U-200 insulin, high-strength insulin · Reviewed

Definition: Concentrated insulin holds more than the standard 100 units per mL. Examples are Humulin R U-500 (500 units/mL), Toujeo (U-300) and Tresiba U-200. Their pens show the actual dose in units, so no conversion is done. The labels warn never to draw them out of the pen into a syringe.

Why the syringe warning matters

A standard insulin syringe is marked for U-100 insulin. The Humulin R U-500 label says it is 5 times as concentrated as U-100, and drawing it from the pen into a syringe can cause overdose and severe low blood sugar. The Toujeo and Tresiba labels give the same warning.

Worked example: the same mark, five times the insulin

  1. On a U-100 syringe, the 20-unit mark holds 0.2 mL.
  2. With U-100 insulin, 0.2 mL is 20 units.
  3. With U-500 insulin, 0.2 mL is 0.2 x 500 = 100 units.
  4. The syringe reads 20 but delivers 100 units. That is why the labels rule it out.

Who uses it

Concentrated insulins on current labels
ProductStrengthPen step and maximum per injection
Humulin R U-500 KwikPen500 units/mL5-unit steps, up to 300 units
Toujeo Max SoloStar300 units/mL2-unit steps, up to 160 units
Tresiba U-200 FlexTouch200 units/mL2-unit steps, up to 160 units

Humulin R U-500 is only for people who need more than 200 units of insulin a day, and its label says severe lows may develop as long as 18 to 24 hours after an injection.

Why it matters for your log

Log the dose in units as the pen shows it, and record the product name, so a U-100 and a concentrated pen are never mixed up. See insulin syringe units for how syringe marks map to volume.

Read more on Dose Track: Humulin R U-500 side effects · Toujeo side effects · Tresiba side effects · U-40 vs U-100 syringes

General education drawn from labels and published studies, not personal medical advice. Your prescriber, pharmacist and the label that came with your product are the final word.
Basal insulinBasal insulin is long-acting insulin, usually injected once a day, that gives a steady background level of… Insulin syringe unitsThe units on an insulin syringe are marks of volume. On a U-100 syringe, 1 unit = 0.01 mL; on a U-40… U-100 syringeA U-100 syringe is an insulin syringe marked for insulin that holds 100 units per mL. Each unit mark… Insulin pen (injection pen)An insulin pen is a prefilled device that holds several doses of a liquid medicine. You attach a new pen… HypoglycemiaHypoglycemia means low blood glucose (blood sugar). MedlinePlus says that for many people with diabetes…

Frequently asked questions

Can I draw U-500 insulin into a U-100 syringe?+
The Humulin R U-500 label says not to: it is 5 times as concentrated, and drawing it from the pen into a syringe can cause overdose and severe low blood sugar.
Do I need to convert units on a U-300 pen?+
No. The Toujeo label says the dose counter shows units with no conversion needed.

Sources

  1. Humulin R U-500 (insulin human 500 units/mL) US prescribing information, DailyMed
  2. Toujeo (insulin glargine 300 units/mL) US prescribing information, DailyMed
  3. Tresiba (insulin degludec) US prescribing information, DailyMed

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