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Taking people in United StatesPhase 2

Metformin and the growth of abdominal aortic aneurysms

Tests whether metformin changes how fast abdominal aortic aneurysms grow.

Key facts

Who runs it
Stanford University
Where
Stanford, United StatesSee the site
Trial code
Registry title
Limiting AAA With Metformin (LIMIT) Trial
Status
Recruiting
Phase
Phase 2
People taking part
314 people, planned
Started
28 Feb 2022
Expected to end
30 Jun 2028
Type of study
Interventional, 2 groupsOne group gets an existing treatment, for comparison.
Treatments tested
  • Metformin
  • Placebo
Record updated
18 April 2025

Who can take part

AI summary

From the trial's eligibility criteria. Machine-read from the registry text on this page, so it can be wrong. The registry text below and the trial team decide who can take part.

The trial is looking for adults with a small to medium abdominal aortic aneurysm (a swelling of the main artery in the belly) who do not have diabetes. It tests whether metformin slows the aneurysm's growth.

Age
50 to 95 years
Sex
Men and women
Disease stage
Aneurysm below the kidneys, measured by CT scan: 35 to < 50 mm wide in men, 30 to < 45 mm wide in women.
Earlier treatment
No earlier surgery to repair the aneurysm.
Biomarker or test result
Kidney function (eGFR) of ≥ 30 ml/min/1.73 m2. HgbA1c (blood sugar test) of ≤ 6.5%.

Main reasons for not taking part

  • Diabetes, or taking medicine for diabetes
  • Allergy to metformin
  • Aneurysm repair expected within two years, or expected survival under two years
  • Aneurysm in the chest aorta, or conditions like Marfan or Ehlers Danlos syndrome
  • Severe liver disease, severe anemia (Hgb < 10g/dl), pregnancy or breastfeeding

The registry criteria, word for word

Show all 10 criteriaShow less

Other criteria

  • 7.2 Inclusion Criteria
  • Provision of signed and dated informed consent
  • Stated willingness to comply with all study procedures and availability for the duration of the study
  • Male or female, aged 50 to 95 years inclusive
  • Have a maximal orthogonal infrarenal aortic diameter between 35 and < 50 mm for males and between 30 and < 45 mm for females as measured by CTA
  • Eligible participants must have an estimated glomerular filtration rate (eGFR) of ≥ 30 ml/min/1.73 m2 at the initiation of trial participation, and must remain ≥ 30 ml/min/1.73 m2 throughout the term of the study to continue participation
  • HgbA1c must be ≤ 6.5% at initiation to receive study medication
  • Ability to take oral medication and be willing to adhere to the medication regimen throughout the course of the trial
  • Must be willing and able to undergo two computed tomographic aortograms (CTA, with timed intravenous iodinated contrast injections if possible) at initiation and termination of study participation
  • For females of reproductive potential: use of highly effective contraception for at least 1 month prior to screening, with an agreement to use such a method of contraception during study participation and for an additional 4 weeks after the end of study drug administration; 7.3 Exclusion Criteria 1. Diagnosis of, or taking medications for, diabetes mellitus, as defined as HgbA1c > 6.5% at baseline evaluation; 2. Known hypersensitivity to metformin hydrochloride. Individuals with known prior anaphylactic reaction to iodinated contrast will have the option of CT scan without contrast or will not be eligible to participate. Individuals with a prior allergic reaction not including anaphylaxis will be managed with the standard CT protocol for premedication for allergy to contrast - 3 doses of prednisone (50 mg p.o. per) beginning 13 hours prior to the procedure as well as 50 mg of Benadryl p.o. Premedication start times are as follows: 13 hours before contrast, 50 mg PO prednisone 7 hours before contrast, 50 mg PO prednisone; 1 hour before contrast, 50 mg PO prednisone + 50 mg PO diphenhydramine These individuals will also be given the option of CT scan without contrast if unwilling to follow the premedication as indicated above; 3. Presence of metabolic acidosis, defined as total CO2 below the lower limit of normal on chemistry panel obtained during determination of study eligibility; 4. Expected survival less than two years; 5. Prior surgical AAA repair, or anticipated repair within two years; 6. Known thoracic aortic aneurysm disease, as defined as a prior dissection or thoracic aortic diameter > 5 cm); 7. The presence of known syndromic aortic conditions, including but not limited to Ehlers Danlos or Marfan Syndromes, or the at-risk allele in the ACTA2 gene mutation or similar conditions; 8. Severe liver disease, jaundice, or active hepatitis; 9. Severe anemia, defined as a Hgb < 10g/dl; 10. Concurrent participation in other investigational drug trials; 11. For female participants of childbearing potential: pregnancy, intent to become pregnant, lactation, or unwilling or unable to use an effective method of contraception; 12. Alcoholism or chronic excessive alcohol intake; 13. Common iliac artery aneurysms > 3.5 cm; 14. Uncontrolled hypertension defined as Systolic BP≥200, or considered to have hypertensive emergency or urgency

Check if you might fit

Answer for yourself. This is not a decision: only the study team can say whether you can take part.

  • Are you between 50 and 95 years old?

Where in United States

  • Stanford Hospital and ClinicsStanford, United StatesContact: Lori McDonnellTaking people

About the trial

What the trial wants to find out

In this research, the investigators are looking at the effects of a drug called metformin may have on the growth of abdominal aortic aneurysm (AAA)s. AAA is an abnormal enlargement of the aorta, which is the large artery in the abdomen (stomach area). The enlargement of the aorta carries a risk that it will rupture and cause life-threatening bleeding in the abdomen (belly). In this study the investigators hope to learn how metformin is associated with the enlargement or change in size of the AAA in study participants. Smaller studies have suggested that metformin may reduce the rate at which aortic aneurysms enlarge. This study will test this question: does metformin prevent AAAs from growing larger?

The 2 groups in the trial

  • Metformin groupExisting treatment, for comparison

    Participants will either be assigned to take metformin 500 mg tablet(s) daily or identical tablet(s) that contain no active drug, also taken every day. Over the first four weeks of the study, you will increase your dosage every week by one pill, so at the end of the first month you will be taking up to four pills per day. If you develop any symptoms or side effects from pill ingestion during this process, your dose will be decreased to the last number of pills you were able to take without developing side effects.

    Treatment: Metformin

  • Placebo GroupPlacebo, for comparison

    Participants will either be assigned to take metformin 500 mg tablet(s) daily or identical tablet(s) that contain no active drug, also taken every day. Over the first four weeks of the study, you will increase your dosage every week by one pill, so at the end of the first month you will be taking up to four pills per day. If you develop any symptoms or side effects from pill ingestion during this process, your dose will be decreased to the last number of pills you were able to take without developing side effects.

    Treatment: Placebo

Questions to ask the study team

  1. How often do I need to come in, and for how long each time?
  2. Are travel costs paid?
  3. Can I keep my own doctor?
  4. What happens if I want to stop?

Contact the study team: see the registry record → Contacts and Locations

Print a page for my doctor

Data and sources

Registry record
Listed on ClinicalTrials.gov.
Official title
LIMItIng AAA With meTformin (LIMIT) Trial
Plain-language title
Metformin and the growth of abdominal aortic aneurysmsGenerated from the registry record. The registry title is the official one.
AI summary
From the trial's eligibility criteria. Read by machine on 14 November 2026.
Fit questions
Built from NCT04500756, who can take part
Record updated
18 April 2025