Humulin R U-500 vs U-100: Concentrated vs Regular Insulin
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[Diabetes · Human insulin · Comparison]

Humulin R U-500 vs Humulin R U-100: how do the two strengths differ?

Who · Strength · Timing · Warnings

Short answer: Both are regular human insulin. Humulin R U-500 is 5 times as concentrated and is only for people who need more than 200 units a day; it comes in a KwikPen and is usually injected two or three times daily.1 Humulin R U-100 comes in vials, is injected about 30 minutes before meals, and can be given into a vein under supervision.2 Neither has a boxed warning.

How do Humulin R U-500 and U-100 compare side by side?

From the US Humulin R U-500 and Humulin R U-100 labels. Neither label gives side-effect percentages.
Humulin R U-500Humulin R U-100
Strength500 units/mL1100 units/mL2
WhoAdults and children needing more than 200 units a day1Adults and children with diabetes2
Form3 mL KwikPen (1,500 units), 5-unit steps, up to 300 units per injection110 mL and 3 mL vials, drawn up with a syringe2
WhenUsually two or three times daily, about 30 minutes before meals1About 30 minutes before meals, usually with an intermediate or long-acting insulin2
How long it actsMean 21 hours (13 to 24) after 50 or 100 units in obese volunteers1About 8 hours (3 to 14); about 18 hours with 50 or 100 units in obese subjects2
Into a vein or pumpNeither1Into a vein only under medical supervision2
In-use storagePen: 28 days, not refrigerated1Vial: 31 days2
Boxed warningNone1None2

Reviewed . Half-life figures are shown only where the value Dose Track uses agrees with the cited source.

What safety steps are specific to U-500?

The U-500 KwikPen shows the actual units to inject, so no conversion is done. The label warns never to draw U-500 from the pen into a syringe, which can cause an overdose and severe low blood sugar. It also says severe lows may develop as long as 18 to 24 hours after an injection, and that use with other insulins or in a pump has not been studied.1

Humulin R U-100 can be mixed in a syringe with Humulin N, drawing Humulin R first, and may be diluted under medical supervision.2 Both labels list low blood sugar as the most common reaction, and neither gives a missed-dose rule.12

Which, if either, fits is for your prescriber. More detail: Humulin R U-500 side effects, Humulin R side effects, the Humulin R U-500 and Humulin R dosing schedules, the regular insulin guide, and Novolin R vs Humulin R: what differs between the two regular insulins?.

Novolin R vs Humulin R: what differs between the two regular insulins?Same insulin and timing, different pens and storage Humulin R vs Humalog: how does regular insulin compare with rapid-acting?Compared directly in the Humalog label's trials Humulin N vs Lantus: how does NPH insulin compare with glargine?Intermediate NPH vs once-daily long-acting glargine

Frequently asked questions

Who is Humulin R U-500 for?+
Only people who need more than 200 units of insulin a day.1
Do I convert the dose on the U-500 pen?+
No. The U-500 KwikPen dose window shows the units to inject. The label warns never to draw it into a syringe.1
What if I miss a dose?+
Neither label gives a missed-dose rule. Ask your prescriber or pharmacist.12
Can Dose Track log my insulin?+
Yes. You can log each dose in units and set reminders.

Sources

  1. Humulin R U-500 (insulin human) injection prescribing information and Patient Information, sections 1, 2, 3, 5, 6, 12.2 and 16. DailyMed, version of September 2, 2026.
  2. Humulin R (insulin human) injection U-100 prescribing information and Patient Information, sections 1, 2, 3, 5, 6, 12.2 and 16. DailyMed, version of September 7, 2026.

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