What is the volume in milliliters of a 100 unit (International Unit) insulin syringe?

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Last updated: May 27, 2025View editorial policy

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From the Guidelines

A 100 unit diabetes syringe holds 1 milliliter (1 mL) of fluid, as indicated by the most recent evidence from 2023 1. This is because insulin concentration is standardized at 100 units per milliliter (U-100) in most countries, including the United States. When a syringe is marked for 100 units, it corresponds exactly to 1 mL of volume. This standardization is important for accurate insulin dosing, as even small measurement errors can significantly affect blood glucose control. For patients using insulin, understanding this equivalence helps ensure proper medication administration. The markings on these syringes are specifically calibrated for insulin, with each small line typically representing 2 units (or 0.02 mL), as supported by previous studies 1. Some patients with very insulin-sensitive conditions may use smaller capacity syringes (such as 30 or 50 unit syringes) for more precise dosing of smaller amounts. Key points to consider include:

  • The most common syringe sizes are 1 mL, 0.5 mL, and 0.3 mL, allowing doses of up to 100 units, 50 units, and 30 units of U-100 insulin, respectively 1.
  • Insulin pens offer added convenience by combining the vial and syringe into a single device, and may be preferred for individuals with dexterity issues or vision impairment 1.
  • Proper insulin technique is a requisite to obtain the full benefits of insulin injection therapy, and patients should be educated on the proper use of syringes and pens 1.

From the FDA Drug Label

PRINCIPAL DISPLAY PANEL Levemir® Insulin detemir (rDNA origin) injection NDC 68258-8977-01 List 368712 100 units/mL (U-100) 10 mL For subcutaneous use only Rx Only The 100 unit diabetes syringe is designed to hold 1 mL of insulin, as it is a U-100 syringe, meaning it has 100 units/mL.

  • Key point: 100 units = 1 mL 2

From the Research

Insulin Syringe Capacity

  • The provided studies do not directly address the capacity of a 100 unit diabetes syringe in milliliters.
  • None of the studies 3, 4, 5, 6, 7 mention the specific volume of a 100 unit diabetes syringe.
  • The studies primarily focus on insulin pump therapy, insulin regimens, and the management of diabetes, but do not provide information on the capacity of insulin syringes.

Relevant Information

  • The studies discuss various aspects of insulin therapy, including insulin pumps, continuous subcutaneous insulin infusion, and insulin regimens for type 1 and type 2 diabetes.
  • However, they do not provide the specific information needed to answer the question about the capacity of a 100 unit diabetes syringe in milliliters, as cited in 3, 4, 5, 6, 7.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Type 2 Diabetes Mellitus: Outpatient Insulin Management.

American family physician, 2018

Research

Insulin Pumps: Review of Technological Advancement in Diabetes Management.

The American journal of the medical sciences, 2019

Research

The current schemes of insulin therapy: Pro and contra.

Diabetes research and clinical practice, 2021

Research

A Clinical Overview of Insulin Pump Therapy for the Management of Diabetes: Past, Present, and Future of Intensive Therapy.

Diabetes spectrum : a publication of the American Diabetes Association, 2019

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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