Finasteride, Dutasteride and Insulin Action


The purpose of this study is to see if an enzyme in the body (5-alpha reductase, 5αR) is important in controlling how the body handles sugar and fat. The investigators believe that 5αR is a crucial step in regulating these actions as well as controlling how insulin works in the body but regulating the amount of steroid hormones including cortisol and testosterone in the body. In previous clinical studies, the investigators have shown that the activity of 5αR increases as you gain weight and decreases with weight loss. In addition, work that the investigators have performed in the laboratory has shown that if you increase 5αR levels in liver cell grown in the laboratory, the amount of fat that they contain increases. The investigators would therefore like to demonstrate the effect of inhibition 5αR on the regulation of insulin, glucose and fat in the body.

Full Title of Study: “An Open Label Study of 5α-reductase Inhibition on the Regulation of Insulin Action and Metabolic Phenotype in Healthy Volunteers.”

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Parallel Assignment
    • Primary Purpose: Treatment
    • Masking: None (Open Label)
  • Study Primary Completion Date: October 2013


  • Drug: Finasteride
    • Finasteride 5mg once daily for 3 weeks
  • Drug: Dutasteride
    • Dutasteride 0.5mg once daily for 3 weeks

Arms, Groups and Cohorts

  • Experimental: Finasteride
    • Finasteride treatment 5mg for 3 weeks
  • Experimental: Dutasteride
    • Dutasteride treatment 0.5mg for 3 weeks

Clinical Trial Outcome Measures

Primary Measures

  • insulin sensitivity
    • Time Frame: 3 weeks
    • stable isotope measurements of glucose production rate and glucose disposal

Secondary Measures

  • adipose tissue insulin sensitivity
    • Time Frame: 3 weeks
    • insulin mediated suppression of glycerol release into adipose tissue

Participating in This Clinical Trial

Inclusion Criteria

  • Male sex – Age 18-65years – BMI 20-35kg/m2 – BMI >35kg/m2 Exclusion Criteria:

  • Diabetes Mellitus – Glucocorticoid use within the last 6 months – Uncontrolled hypertension (BP>160/100mmHg) – Drugs know to impact upon glucocorticoid metabolism

Gender Eligibility: Male

Minimum Age: 18 Years

Maximum Age: 65 Years

Are Healthy Volunteers Accepted: Accepts Healthy Volunteers

Investigator Details

  • Lead Sponsor
    • University of Birmingham
  • Provider of Information About this Clinical Study
    • Principal Investigator: Dr Jeremy Tomlinson, MRC Senior clinical fellow and Reader in Endocrinology – University of Birmingham

Clinical trials entries are delivered from the US National Institutes of Health and are not reviewed separately by this site. Please see the identifier information above for retrieving further details from the government database.

At, we keep tabs on over 200,000 clinical trials in the US and abroad, using medical data supplied directly by the US National Institutes of Health. Please see the About and Contact page for details.