A Trial of Tadalafil and Glycemic Traits

Thomas J. Wang, MD73 enrolled

Overview

The purpose of this study is to find out if tadalafil can help overweight and obese people metabolize blood sugar more efficiently. The investigators also want to find out if 20 mg/day of tadalafil for 3 months is safe to take without causing too many side effects. The investigators are plan to enroll 100 subjects at Massachusetts General Hospital (MGH).

This study is examining changes in insulin resistance and glucose tolerance following 3 months of treatment with oral, once daily tadalafil. The investigators primary hypotheses are that measurable decreases in insulin resistance (as measured by HOMA-IR) and increases in insulin sensitivity (as measured by the Matsuda index) will occur following 3 months of treatment with oral tadalafil 20 mg daily compared to placebo. The investigators secondary hypotheses are that improvements in average glycemia (as measured by hemoglobin A1C), pancreatic beta cell function (as measured by the oral disposition index), and body composition (including weight, waist circumference, body mass index, and waist-hip ratio) will occur as a result of tadalafil-mediated changes in the cGMP pathway.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

DOUBLE

Enrollment

Conditions

Cardiovascular Disease Insulin Resistance Glucose Intolerance Obesity

Interventions

TadalafilDRUG

20 mg Tadalafil taken once a day for 3 months

PlaceboDRUG

Placebo tablet taken by mouth once a day for 3 months

Eligibility

Sex: ALLMin age: 18 YearsMax age: 50 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: * Age \> 18 years and \< 50 years * BMI \> 30 kg/m2 * Fasting insulin \> 10 uU/mL Exclusion Criteria: * Systolic blood pressure (SBP) \< 100, \> 150 mmHg * Current anti-hypertensive medication use, including diuretics * Current use of organic nitrates * Current use of PDE-5 inhibitors (sildenafil, tadalafil, vardenafil) * History of reaction to PDE-5 inhibitors * Known HIV infection * Use of medications that strongly alter CYP3A4 activity * History of myocardial infarction, angina, uncontrolled cardiac arrhythmia, stroke, transient ischemic attack, or seizure * Known non-arteritic ischemic optic retinopathy (NAIOR) * History of hearing loss * Estimated glomerular filtration rate (eGFR) \< 60 ml/min/1.73 m2 by the modified diet in renal disease (MDRD) equation * Hepatic transaminase (AST and ALT) levels greater than three times the upper limit of normal * Known pregnancy or those unwilling to avoid pregnancy during the course of the study * History of priapism * Use in excess of four alcoholic drinks daily * History of diabetes mellitus or use of anti-diabetic medications * Known anemia (men, Hct \< 38% and women, Hct \< 36%)

Locations (1)

Massachusetts General Hospital

Boston, Massachusetts, United States

Outcomes

Primary Outcomes

Change in Insulin Resistance From Baseline to 3 Months, as Measured by HOMA-IR

The primary endpoint is defined as the treatment group difference in the change in insulin resistance (baseline HOMA-IR minus 3-month HOMA-IR). HOMA-IR = \[fasting glucose \* fasting insulin\]/405

Time frame: Baseline and 3 months

Secondary Outcomes

Baseline to 3-month Change in Insulin Sensitivity, as Measured by the Matsuda Index

The secondary endpoint is defined as the treatment group difference in the change in Matsuda Index (baseline minus 3-month). This index is a measure of insulin resistance derived from a frequently sampled oral glucose tolerance test, obtaining glucose and insulin levels in the fasting state, as well as 30, 60, 90, and 120 min after administration of oral glucose load. Matsuda index = 10,000/SQRT \[fasting glucose\*fasting insulin\* (mean glucose from time 30, 60, 90, 120 min) \* (mean insulin at time 30, 60, 90, and 120 min)\]

Time frame: Baseline and 3 months

Baseline to 3-month Change in Endothelial Function Measured by EndoPAT

Endothelial function was measured using the reactive hyperemia index, acquired using EndoPAT device. Peripheral arterial tonometry probes were placed on both index fingers. After a 5 min equilibration period, a blood pressure cuff was inflated to 200 mmHg and kept inflated for 5 min. The cuff was then rapidly deflated and the reactive hyperemic response pulse volume recorded, where RHI = ratio of hyperemic finger pulse volume (post-cuff inflation / pre-cuff inflation) to control finger pulse volume (post-cuff inflation / pre-cuff inflation)

Time frame: Baseline and 3 months

Insulinogenic Index

The secondary endpoint is defined as the treatment group difference in the change in insulinogenic index (baseline minus 3-month). This index is thought to reflect insulin secretion, and is derived from fasting and 30 min-post oral glucose tolerance testing glucose and insulin values. Insulinogenic index = \[fasting insulin - insulin at time 30 min\] / \[fasting glucose - glucose at time 30 min\]

Data from ClinicalTrials.gov

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