Mechanisms for Activation of Beige Adipose Tissue in Humans

Phase 2

Recruiting

• Conditions: PreDiabetes
• Interventions: Drug: Placebo; Drug: Mirabegron

• Registration Number: NCT04666636
• Lead Sponsor: Philip Kern

Brief Summary

Mirabegron (Myrbetriq®, Astellas) is a highly specific and well-tolerated ß3 agonist marketed for overactive bladder. This trial will assess the effects of mirabegron on glucose tolerance and adipose tissue in prediabetic patients

Detailed Description

Among the many survival adaptations developed by mammals is a defense against the cold and hypothermia; one of these adaptations is the ability to uncouple oxidative phosphorylation and generate heat, rather than adenosine triphosphate (ATP), from lipid substrate in specialized tissues, and there has been much interest in exploiting this inefficient metabolism for the treatment of obesity and insulin resistance. Brown adipose tissue (BAT) protects against obesity in mice, and studies have documented cold-induced BAT in humans using positron emission tomography (PET-CT) scanning. Additional studies have demonstrated that white adipose tissue (WAT) can upregulate its thermogenic capacity and become "beige", and this beiging of SC WAT likely provides an additional defense against the cold.

Brown and beige fat can be activated by cold temperatures, or through catecholamines. The catecholamines epinephrine and norepinephrine have undesirable side effects. However, adipocytes are among the few cells that contain ß3 adrenergic receptors (ß3AR), whereas the heart is dominated by ß1 and ß2 receptors. Therefore, a drug that could target the ß3AR could activate brown/beige fat without cardiovascular side effects. Recently, there have been human studies performed and obese human subjects participants were treated with the ß3AR agonist mirabegron. This resulted in improved glucose homeostasis by increasing insulin sensitivity and insulin secretion. It was also found that mirabegron treatment of obese adults did not increase BAT or induce weight loss, but instead induced beige fat, along with increased insulin sensitivity, which was accompanied by an increase in type I fibers in skeletal muscle. Mirabegron treatment stimulated subcutaneous (SC) WAT beiging, lipolysis, and remodeling. However, unlike WAT, insulin-producing ß-cells and muscle do not express the ß3AR; therefore, it is thought that the beneficial effects of mirabegron treatment occurred by an indirect mechanism.

Currently, mirabegron (Myrbetriq®, Astellas) is a highly specific and well-tolerated ß3 agonist marketed for overactive bladder. It is hypothesized that mirabegron treatment of prediabetic subjects will improve glucose homeostasis through improved insulin sensitivity and ß-cell function, in addition to other changes in adipose tissue. Additionally, mirabegron treatment may change the plasma composition of proteins, lipids, metabolites, short-chain fatty acids, or exosomal miRNAs that are known to affect peripheral tissue function.

This trial will quantify the effects of the ß3 agonist mirabegron on glucose metabolism and adipose tissue in a placebo-controlled trial and determine some of the mechanistic underpinnings of these effects.

Study Timeline

• Study Start: 2020-12-07
• Study First Submitted: 2020-12-07
• Study First Submitted QC: 2020-12-07
• Study First Posted: 2020-12-14
• Status Verified: 2025-01
• Last Update Submitted: 2025-01-17
• Last Update Posted: 2025-01-20
• Primary Completion: 2026-01-31
• Study Completion: 2026-01-31

Recruitment & Eligibility

• Status: RECRUITING
• Sex: All
• Target Recruitment: 65

Inclusion Criteria

• BMI 27-45
• prediabetes (A1c 5.7-6.4)
• impaired fasting glucose or impaired glucose tolerance

Exclusion Criteria

• diabetes
• chronic use of anti-diabetic medication
• acute or chronic inflammatory condition
• unstable medical condition
• cancer
• renal insufficiency
• any contraindication for Mirabegron
• BMI >45

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Placebo	Placebo	Participants in the group will receive placebo.
Mirabegron	Mirabegron	Participants in this group will receive Mirabegron for 16 weeks.

Primary Outcome Measures

Name	Time	Method
Change in Insulin Secretion	16 weeks (at baseline and at 16 weeks)	Insulin secretion will be measured with a euglycemic clamp.
Change in Resting Metabolic Rate	16 weeks (at baseline and at 16 weeks)	Resting Metabolic Rate (RMR) will be measured using indirect calorimetry.
Change in Brown Adipose Tissue Activity	16 weeks (at baseline and at 16 weeks)	Brown adipose tissue (BAT) activity will be measured using water-vest cold stimulation combined with positron emission tomography (PET-CT).
Change in Peripheral Insulin Sensitivity	16 weeks (at baseline and at 16 weeks)	Peripheral insulin sensitivity will be measured with a euglycemic clamp.
Change in glycohemoglobin	16 weeks (at baseline and at 16 weeks)	Hemoglobin A1c (HbA1C) will be measured from blood samples.
Change in Glucose Tolerance	16 weeks (at baseline and at 16 weeks)	The standard oral glucose tolerance test (OGTT) using 75g glucose will be used to assess tolerance.
Change in Body Composition	16 weeks (at baseline and at 16 weeks)	Body composition (percent body fat) will be measured using dual-energy X-ray absorptiometry (DEXA).

Trial Locations

Locations (1)

University of Kentucky; 🇺🇸 Lexington, Kentucky, United States