Inflammatory Response to CSII Catheters in a Tummy Tuck Model (IRCATT)

July 29, 2025 updated by: Medical University of Graz

A Pilot Study for the Systematic Evaluation of the Inflammatory Response to Commercially Available Insulin Infusion Catheters in Subcutaneous Adipose Tissue

In insulin pump therapy, insulin is continuously infused into the subcutaneous adipose tissue via a continuous subcutaneous insulin infusion (CSII) catheter using a basal/bolus pattern. Unfortunately, insulin absorption from the tissue surrounding a CSII catheter can be slow, variable, and unreliable. It is recommended to replace CSII catheters after 2 to 3 days of use. Frequently changing the injection site can be tedious and moreover leads to scarring, while reusing the same injection site can lead to medical complications such as lipohypertrophy. CSII catheters are manufactured from both steel and Teflon and use of either of these materials is based on personal preference/experience rather than scientific, empirical data. We hypothesize that the inflammatory response to CSII catheters is a major contributor to variable insulin absorption and that this response is significantly different between materials and catheters shapes. In order to develop CSII catheters with an extended life-time up to 7 days, we need to better understand the inflammatory response caused by the introduction and maintenance of a CSII catheter into the subcutaneous adipose tissue. This study is a pilot study in humans scheduled for elective plastic surgery where a large skin flap is removed from the abdominal region. Teflon and steel CSII catheters will be inserted into the abdomen 7, 4, and 3 days prior to surgery. This study design allows for the removal of tissue plugs surrounding CSII catheters without causing additional scarring for the patient.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

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Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Background:

Approximately one million patients worldwide manage their diabetes with an insulin pump. Insulin is continuously infused into the subcutaneous adipose tissue via a Continuous Subcutaneous Insulin Infusion (CSII) catheter using a basal/bolus pattern that can be adjusted by the patient according to meal times, mimicking the natural function of the pancreas. One major advantage of this form of therapy is the improvement of living quality. Compared to multiple daily insulin injections, the catheter has to be inserted only once every 2-3 days where it remains within the subcutaneous tissue. This is especially advantageous for children of young age.

Unfortunately, insulin absorption from the tissue surrounding a CSII catheter can be slow, variable, and unreliable. It is recommended to replace infusion sets and CSII catheters after 2 to 3 days of clinical use. After this time, blood glucose control becomes difficult for the patient because insulin absorption from the subcutaneous tissue into the blood stream and lymphatics becomes highly variable.

The underlying mechanisms for impaired insulin absorption are poorly understood and the knowledge of rotating the site of injection is based on user experience. Frequently changing the injection site can be tedious and moreover leads to scarring, while reusing the same injection site can lead to medical complications such as lipohypertrophy. In order to develop CSII catheters with an extended life-time up to 7 days, there is a need to better understand the inflammatory response caused by the introduction and maintenance of a CSII catheter into the subcutaneous adipose tissue. The clinical use of a 7-day CSII catheter with low pharmacokinetics (PK) variability will significantly improve blood glucose control, decrease the risk for hypoglycemia, increase compliance, and decrease cost. Since continuous glucose monitoring (CGM) devices are approved for 7-day wear time, the development of a CSII catheter with extended lifetime is also crucial for the development of single-port artificial pancreas (AP) systems where CSII and CGM are combined in one catheter, mimicking pancreatic function. Furthermore, the improvement of catheter longevity will reduce insertion sites and scars. This is especially important for children with a smaller body surface area.

The choice of one material over the other is largely based on the patient's personal preference, his or her endocrinologist's or diabetes educator's opinion and therapy costs. There is a trend in both the United States and Europe towards using Teflon sets (90 % and 75 %, respectively) but approximately 40 to 45 % of pump users in Germany use steel catheters. Compared to Teflon, steel catheters are easier to insert and are less prone to kinking, and can be worn by patients allergic to Teflon. Patients using steel catheters report better metabolic control, less variable insulin absorption and less unexplained hyperglycemia (Heinemann 2016; Reichert et al. 2013). However, especially during exercise, steel may cause discomfort and the softer and more flexible Teflon catheter is assumed to be more comfortable to wear. The wear-time of the CSII catheter considerably varies between patients (from 2 to 10 days), although recommendations for the optimal frequency of changing an insulin infusion set (2 days for steel and 3 days for Teflon) exist.

In a prior pig study the inflammatory response to commercial CSII catheters comparing steel, Teflon and Teflon with an anti-inflammatory coating was analyzed. There was significant reduction in area of inflammation and macrophage recruitment around the non-coated and coated Teflon catheters. Steel elicited the most severe inflammatory response with significantly higher fibrosis.

Although the pig has proven to be an excellent model for the study of human skin and adipose tissue, there is an urgent medical need to confirm these findings in a human model. For the histopathological and molecular analysis of subcutaneous tissue in the vicinity of the catheter, large amounts of tissue need to be excised from the site of interest. This makes a human study almost impossible. Nevertheless, the generation of human data is crucial and a lot of this important information is still lacking in diabetes research and treatment. The possibility to excise extensive amounts of tissue without causing additional scars or pain (except that caused by the abdominoplasty itself) for the patient presents the main benefit of this study setup.

Aim:

The aim of this study is to compare the inflammatory response to commercially available CSII catheters of two different materials (steel and Teflon) over 1 day, 4 days and 7 days of wear-time in humans scheduled for elective plastic surgery (abdominoplasty).

Hypothesis:

Conventional steel CSII catheters elicit a more severe acute inflammatory response in the subcutaneous adipose tissue than Teflon CSII catheters.

H0 = there is no difference in mean area of fibrin deposition around catheters H1 = there is a significant difference in mean area of fibrin deposition between catheters

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
20

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

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Study Contact Backup

Study Locations

  • Austria
      • Graz, Austria, 8036
        • Division of Plastic, Aesthetic and Reconstructive Surgery

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years to 99 years (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Men and women, age 18 years or older
  • Scheduled elective abdominoplasty at the Dpt. of Plastic Surgery, Medical University of Graz
  • Signed informed consent form

Exclusion Criteria:

  • Allergy to Teflon or steel
  • Known skin diseases (atopic dermatitis, psoriasis)
  • History of immunodeficiency diseases
  • Patients on glucocorticoid or other immunomodulating therapy
  • History of bleeding disorder
  • Pregnancy or planned pregnancy
  • Unable to fully understand study procedures and to provide informed consent

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Insertion of Insulin Infusion Catheters
Non-diabetic patients scheduled for abdominoplasty will be inserted continuous subcutaneous insulin infusion (CSII) catheters of two different materials into the part of the abdomen which will be removed during surgery.
Device: Continous Subcutaneous Insulin Infusion Catheter
Catheters will be inserted into the abdomen of each patient using aseptic technique according to the following schedule: (1) 8 days before surgery, (2) 4 days before surgery and (3) 1 day before surgery (Table 1). At each time point 2 steel (Medtronic Sure-T, 9 mm) and 2 Teflon (Medtronic Quick-set®, 9 mm) CSII catheters will be inserted into the subcutaneous abdominal tissue. In total, 12 catheters will be inserted into each patient's abdomen using only the area predefined by the plastic surgeon for removal.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Area of inflammation (mm2)
Time Frame: 7 days
Assessed by microscopy; area of inflamed tissue, including cell infiltration, necrosis, fibrin/collagen deposition
7 days

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Area of fibrin deposition (mm2)
Time Frame: 7 days
Assessed by microscopy; area of fibrin
7 days
Area of fat necrosis (mm2)
Time Frame: 7 days
assessed by microscopy; area of necrosed adipocytes
7 days
Inflammation distance (mm)
Time Frame: 7 days
assessed by microscopy; distance from skin surface to lowest point of microscopically assessed inflammation
7 days
Cytokine gene expression (fold change)
Time Frame: 7 days
Assessed by qPCR; relative fold change in gene expression compared to non-traumatized tissue (IL-1b, TNFa, TGFb, IL-6, IL-8, IL-10)
7 days
Macrophage marker gene expression (fold change)
Time Frame: 7 days
Assessed by qPCR; relative fold change in CD68 gene expression compared to non-traumatized tissue
7 days

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Medical University of Graz

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Lars-Peter Kamolz, MD Prof, Medical University of Graz

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
February 1, 2018

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
May 9, 2023

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 31, 2024

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
September 21, 2017

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
September 26, 2017

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
October 2, 2017

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
August 1, 2025

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 29, 2025

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
July 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • IRCATT

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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Conditions

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