The Physiological Responses and Adaptation of Brown Adipose Tissue to Chronic Treatment With Beta3-Adrenergic Receptor Agonists

Recruiting now · Phase 1 · Has a placebo group

Conditions studied: Polycystic Ovary Syndrome

In brief

Background: Brown adipose tissue (BAT) is a type of fat in the body. It may prevent weight gain, improve insulin sensitivity, and reduce fatty liver. Researchers want to see if BAT helps the body burn energy. Objective: To learn more about how BAT works to burn energy. Eligibility: People ages 18-40 with a body mass index between 18 and 40 Design: Participants will be screened with: Medical history Physical exam Blood, urine, and heart tests Dietitian interview Participants will have an overnight baseline visit. This includes: Repeats of screening tests Exercise test Scans. For one scan, a radioactive substance is injected into the arm. FSIVGIT: An IV is inserted into veins in the right and left arms. Glucose and insulin are injected in one arm. Blood glucose and insulin levels are measured from the other. Metabolic suite: Participants stay 18-19 hours in a room that measures their metabolic rate. Monitors on the body measure heart rate, movement, and temperature. Optional fat biopsy: A small piece of tissue is removed with a needle. Participants will take 2-4 pills daily for 4 weeks. All women will take the drug mirabegron. Men will be randomly get either the drug or a placebo. All participants will have a visit after 2 weeks of the pills. They will repeat the screening tests. Participants will have an overnight visit 2 weeks later. They will repeat the baseline tests. Participants will keep food and medication diaries. Participants will have a follow-up visit 2 weeks after stopping the pills. This includes heart tests.

Key facts

Study ID

NCT03049462

Run by

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

People needed

100

Starts

2017-03-13

Expected to finish

2026-09-30

Last updated by the study team

2026-08-04

Who can join

Age: 18 and older, up to 40. Sex: any. Healthy volunteers: not accepted.

You may not qualify if…

• Hypersensitivity and associated allergic reactions to mirabegron (or similar drug substances or components)
• Abnormal bladder function, diagnosis of bladder outlet obstruction, urinary incontinence, urgency, and urinary frequency or use of antimuscarinic medication to treat overactive bladder (OAB)
• Type 1 or Type 2 Diabetes mellitus, fasting serum glucose >125 mg/dL, and/or an HbA1c test >6.5%
• Hypertension, defined as blood pressure (Bullet)140/90 mmHg, based on WHO guidelines (https://www.who.int/news-room/fact-sheets/detail/hypertension)
• Hypo- or hyper-thyroid disease (TSH >5.0, <0.4 miU/L) that is controlled for less than one year
• Anemia, defined by hemoglobin < 11.3 g/dL (females) or < 13.8 g/dL (males); sickle cell anemia or other blood disorders; and/or wound healing problems
• Cardiovascular disease, cardiac arrhythmias, orthostasis, unstable vasomotor system, or renal impairment
• A clinically significant abnormal ECG and/or QTc interval above normal
• Elevated liver enzymes with probable or diagnosed liver disease (other than fatty liver disease)
• Psychological conditions such as claustrophobia, untreated clinical depression or anxiety, untreated bipolar disorders, or forms of mental incapacity that would be incompatible with safe and successful participation in this study
• Recent history in last 4 weeks of any local or systemic infectious disease with fever or requiring antibiotics
• Self-reported intolerance of cold that would prevent the individual from spending several hours in a chilled room with a cooling vest
• Current use of any drugs known to:
• have major drug-drug interactions with mirabegron
• Prolong QT interval
• Alter glucose metabolism or cause insulin resistance (in last six months)
• Treat diabetes mellitus
• Treat hypertension
• Be drugs of abuse
• Self-reported weight loss or weight gain > 5% in the preceding 6 months.
• Pregnancy, childbirth within the last year, or breastfeeding in the past 12 months
• Individuals who spend >70% of daily hours outdoors since the exposure to varied environmental temperatures will potentially impact the ability to influence and measure BAT activity.
• Addiction to alcohol or substances of abuse within the last 5 years
• Self-reported current alcohol consumption of more than 2 servings of alcohol per day
• Self-reported current use of nicotine and/or tobacco products

Where it is running

• National Institutes of Health Clinical Center — Bethesda, Maryland, United States (enrolling)

Full record on ClinicalTrials.gov

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