Conditions: Insulin Resistance Postmenopause
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 35
Healthy volunteers: yes

Brief summary:
The purpose of this research study is to determine if a relationship between insulin resistance (IR) and testosterone (T) exists in women who have already gone through menopause.

Detailed description:
This study tests the central hypothesis that insulin resistance (IR) increases androgen (male sex hormone) production in postmenopausal women. Participation will include five visits, each lasting on average 2.5 hours, over a period of 13-20 weeks.

At the screening visit, the participant's medical history, current use of medications and dietary supplements, and social habits will be recorded. This information will be reviewed on each subsequent visit; participants are asked to maintain their current diet and physical activity level throughout the study.

A brief physical exam will be performed, and blood will be drawn.

At the 2nd (baseline) visit, patients will undergo a euglycemic-hyperinsulinemic clamp (a procedure to measure insulin sensitivity by continuous intravenous infusion of insulin, and variable infusion of glucose). Blood samples will be drawn throughout the procedure. At completion, the insulin infusion will be stopped, participants will be fed, and the glucose infusion continued for at least 15 minutes to ensure stability of the blood glucose concentration. After the procedure, participants will be randomized to receive either metformin plus leuprolide placebo, leuprolide plus metformin placebo, or metformin placebo plus leuprolide placebo. The leuprolide or leuprolide placebo will be administered as an injection by a nurse. The metformin or metformin placebo will be dispensed to the participant in the form of pills, with instructions for titrating the dose. Participants will be contacted by telephone once weekly during the titration period to assess drug tolerability and adverse events (AEs). Participants will be maintained at their maximum tolerated dose for the duration of the study intervention period.

Participants will return every 4 weeks for follow-up. Blood will be drawn, the nurse will administer the leuprolide or leuprolide placebo injection, and metformin or metformin placebo will be dispensed. At the final visit (week 12), participants will undergo a brief physical exam, and will then undergo a final euglycemic-hyperinsulinemic clamp.

Arms:
arm 1: metformin pill plus placebo injection arm 2: leuprolide injection plus placebo pill arm 3: placebo pill plus placebo injection

Interventions: intervention 1: metformin intervention 2: leuprolide injection intervention 3: placebo pill intervention 4: placebo injection
Intervention descriptions: intervention 1: Initiated on 500 mg daily and titrated up to 1000 mg twice a day during the first four weeks, remaining at that dose until 12 weeks intervention 2: 3.75 mg injection every 4 weeks (e.g. at baseline, 4, and 8 weeks) intervention 3: matching pill twice a day for 12 weeks intervention 4: matching injection every 4 weeks (e.g. baseline, 4, and 8 weeks)

Protocol document: