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NCT Number: NCT04715022

Sympathetic-vascular Dysfunction in Obesity and Insulin Resistance (Vitamin C Study)

The main purpose of research is to examine and understanding the development of hypertension in obese adults with insulin resistance. Findings from our studies will identify unique mechanisms that can be targeted to limit increases in vascular dysfunction and reduce the excessively high prevalence of hypertension and risk for cardiovascular disease (CVD).

This study is testing the health of the blood vessels and the activity of the nerves that control the blood vessels in adults with insulin resistance. The extent to which ascorbic acid (Vitamin C) improves the function of the blood vessels will be determined. The primary outcome is blood pressure, which is the result of blood vessel health and activity of the nerves, and the reduction in blood pressure that is observed with ascorbic acid.

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Key information

Conditions

Hypertension Cardiovascular Diseases Vascular Diseases

Age range

35 year–65 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 1 / Phase 2

Primary location

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Obese: BMI >30 m/kg2
  • Middle-aged: 35-65 years
  • Participants must be willing and able to discontinue taking any vitamin C or E supplements or omega-3 fatty acids beginning 2 weeks prior.
  • Able and willing to provide written informed consent

Exclusion criteria

  • Diabetes mellitus: fasting glucose < 1267 mg/dL and/or HbA1c < 6.5%
  • Currently taking a statin or antihypertension medication
  • Hyperlipidemia: Fasting triglycerides < 250 mg/dL
  • Hypertension: <130/80 mmHg
  • History of heart disease (e.g., myocardial infarction, stent)
  • History of vascular disease (e.g., bypass, stroke)

Treatment and study plan

Ascorbic acid solution (American Regent Laboratories Inc.)

Drug

Ascorbic acid solution (American Regent Laboratories Inc.) will be obtained from the KU Investigational Pharmacy located in the KU Clinical Research Center where studies will take place. A priming bolus of 0.06 g ascorbic acid/kg fat free mass (FFM) dissolved in 100 mL of saline will be infused intravenously at 5 mL/min for 20 minutes, followed immediately by a "drip-infusion" of 0.02 g/kg FFM dissolved in 30 mL of saline administered over 2 hours at 0.5 mL/min.

Saline

Drug

Placebo (saline) will be administered

Primary outcomes

  1. Efficacy of infusion of ascorbic acid

    Time frame: 30 minutes

    The difference in sympathetic-vascular transduction (mmHg) between ascorbic acid and placebo infusion will be taken as a measure of the modulation of SVT by oxidative stress.

  2. Efficacy of infusion of ascorbic acid

    Time frame: 60 minutes

    The difference in sympathetic-vascular transduction (mmHg) between ascorbic acid and placebo infusion will be taken as a measure of the modulation of SVT by oxidative stress.

  3. Efficacy of infusion of ascorbic acid

    Time frame: 90 minutes

    The difference in sympathetic-vascular transduction (mmHg) between ascorbic acid and placebo infusion will be taken as a measure of the modulation of SVT by oxidative stress.

  4. Efficacy of infusion of ascorbic acid

    Time frame: 120 minutes

    The difference in sympathetic-vascular transduction (mmHg) between ascorbic acid and placebo infusion will be taken as a measure of the modulation of SVT by oxidative stress.

Study contacts

Contact information is provided by the study sponsor or research team.

Manuel Clark, MPA

CONTACT

[email protected]

913-945-5763

Seth Holwerda, PhD

CONTACT

[email protected]

9729223230

Sponsors and collaborators

Lead sponsor

University of Kansas Medical Center

Other

Registry information

Official study title

Sympathetic-vascular Dysfunction in Obesity and Insulin Resistance

Important dates

Study start
2021
Primary completion
2026
Study completion
2027
First posted
Jan 20, 2021
Registry last updated
Jun 8, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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