The Division of Vascular and Endovascular Surgery at Stanford Medicine is leading a clinical trial to study the effects of metformin on the growth of abdominal aortic aneurysm (AAA). Metformin is a very common medication that treats type 2 diabetes.

The study, called Limiting AAA with Metformin Trial, or LIMIT, investigates whether the drug prevents the progression (enlargement) of AAAs. Stanford Medicine is currently accepting new patients for this clinical trial, which is funded by the National Heart, Lung, and Blood Institute. The study drug for the trial, as well as additional resources to track medication tolerance, are provided by EMD Serono, a U.S. affiliate of Merck KGaA

Benefits of the LIMIT clinical trial

The vascular surgery team at Stanford Medicine launched this nationwide clinical trial based on findings from earlier studies. The prior studies showed that people who had AAA and type 2 diabetes—and who were taking metformin to control diabetes—experienced less aneurysm disease progression compared to diabetic patients not taking metformin. A prescription for metformin, which was intended to lower blood glucose levels, was consistently associated with reduced rates of AAA enlargement in multiple retrospective studies.

The LIMIT trial will prospectively study whether metformin significantly prevents the enlargement of existing AAAs in non-diabetic people. “This exciting study gives us the opportunity to evaluate the effects of this promising medication on a larger group of patients with AAA,” says Ronald Dalman, MD, vascular surgeon, the Walter C. and Elsa R. Chidester Professor of Surgery at Stanford Medicine, and principal investigator for the LIMIT trial. “Our findings will help determine whether metformin will be an appropriate treatment option for some patients with this life-threatening condition.”

Eligibility for the LIMIT research study

Participation in the LIMIT clinical trial is completely voluntary, and patients can withdraw from the study at any time. Patients may be eligible for the study if they:

• Are between 55 and 90
• Have a diagnosis of AAA with a maximum diameter of 4.9 cm for males or 4.5 cm for females
• Have not had a surgical procedure to repair AAA
• Do not have diabetes and are not taking any diabetic medication, including metformin
• Do not have the following conditions:
  • Severe liver disease
  • Jaundice
  • Active hepatitis
  • Uncontrolled hypertension (systolic blood pressure ≥ 200)
  • Severe anemia (Hgb < 10g/dl)

Details of the LIMIT clinical trial

LIMIT study participants will complete five study assessments over a two-year period. At the baseline visit, patients are randomly assigned to the study drug group or the placebo group. Each participant will submit blood and urine samples, get a CT scan, complete a questionnaire, and receive the study drug. Participants will need to take one pill per day at first and gradually increase the dose, taking up to four pills per day, as tolerated. Some participants will take as little as one pill per day for the duration of the study.

Participants will complete follow-up assessments at six, 12, and 18 months. Some participants may be able to complete these follow-up assessments remotely, either by telephone or video visits. Participants completing in-person follow-up visits will submit blood and urine samples and receive additional supplies of the study drug. They will also complete questionnaires that inquire about their quality of life and other disease-specific issues.

During the study’s final visit at 24 months, patients will give blood and urine samples, return any unused study medications, and get another CT scan. They will also complete a questionnaire about their experience.

Learn more and refer your patients to the LIMIT study

Stanford Medicine encourages you to share information about this research study with your patients. To learn more about the LIMIT clinical trial, contact the study research coordinator, Lori McDonnell, at 650-498-5521 or lorimcd2@stanford.edu.

For additional information and complete eligibility requirements, please download the LIMIT trial brochure, visit the LIMIT clinical trial website, or learn more about the background information for this trial.