The Effects of Metformin on Blood Vessel Structure and Function

Individuals with the Metabolic Syndrome (MeS) are at increased risk for developing cardiovascular diseases. This increased risk may, in part, be related to abnormalities in the blood vessels. MeS is defined as having 3 or more of the following 5 criteria:

• Abdominal obesity (waist measurement >39.8 inches in men, >34.4 inches in women)
• Elevated triglycerides (>150 mg/dl)
• Low HDL or "good" cholesterol (<40 mg/dl in men or <50 mg/dl in women)
• Elevated blood pressure (>130/85) or treatment for high blood pressure
• Elevated fasting blood sugar (>100 mg/dl)

Metformin is a medication that is approved by the Food and Drug Administration (FDA) for the treatment of diabetes; however, it can also be safely administered to non-diabetic subjects. We are evaluating whether Metformin reduces the stiffness of blood vessels and improves endothelial function.

This study requires 4 visits to the NIA Clinical Research Center (located on the premises of Harbor Hospital) over a 5-month period. At the initial visit, patients will be given a physical examination with blood and urine tests, and an EKG. They will be randomized into one of two groups; one group will receive Metformin (1700 mg per day), while the other group will receive a placebo. Participants will take the medication for 4 months. Subsequent visits will include additional blood tests, ultrasound and echo exams.

Taking part in this study is entirely voluntary. All testing and medications will be provided at no cost to the participant or their family.

Inclusion criteria

Participants with the Metabolic Syndrome, which is defined as having 3 or more of the following 5 alterations:

• Abdominal obesity (waist measurement >39.8 inches in men, >34.4 inches in women)
• Elevated triglycerides (>150 mg/dl)
• Low HDL or "good" cholesterol (<40 mg/dl in men or <50 mg/dl in women)
• Elevated blood pressure (>130/85) or treatment for high blood pressure
• Elevated fasting blood sugar (>100 mg/dl)

Exclusion criteria

• Diabetes treated with medication
• Blood pressure >160/100 mmHg
• Clinical Congestive Heart Failure
• Anemia with hematocrit <32%
• Asthma or Chronic Obstructive Pulmonary Disease (COPD) requiring daily medication or use of home oxygen therapy
• Major surgery planned within the next six months
• A recent, unexplained weight loss of >10% of body weight in the past 6 months
• A known allergy or hypersensitivity to Metformin
• History of hepatitis or cirrhosis
• History of kidney disease (defined as serum creatinine >1.4 mg/dL in men, >1.3 mg/dL in women)
• Pregnancy or the absence of an effective method of contraception
• Illicit drug or alcohol abuse
• Cancer requiring treatment currently or recently completed treatment in the last 2 months