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NCT Number: NCT07030010

Effect of a Liquid Tonic Drink on Post-meal Glucose and Insulin Responses

A randomised, double blinded, placebo-controlled crossover design clinical trial conducted at the Mary MacKillop Institute for Health Research (MMIHR, Australian Catholic University) for individuals with overweight/ obesity. This study will measure the postprandial glucose and hormone responses to a high-carbohydrate meal with/ without a liquid tonic drink.

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Key information

Conditions

Overweight or Obese Adults Body Weight Nutrition Disorders Nutritional and Metabolic Diseases Overnutrition Overweight Pathological Conditions, Signs and Symptoms Signs and Symptoms

Age range

30 year–64 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Australian Catholic University

Melbourne, Victoria, 3065, Australia

About this study

Twenty individuals living with overweight/ obesity will be invited to attend the university laboratories on 2 separate occasions to participate in a postprandial (meal) challenge. Participants will consume the same high-carbohydrate meal on each visit, with or without a liquid tonic drink. This will be a cross-over design study, where participants will consume a placebo drink on the alternate visit. Participants will remain in the laboratory for 3-hours following the meal with a venous cannula in place, and have blood samples taken at regular timepoints. Blood samples will be analysed for glucose and appetite hormones. Participants will also wear a continuous glucose monitor throughout the period which encapsulates both study trials.

Who can participate

Healthy volunteers accepted: No

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

Inclusion criteria

  • Aged ≥30-64 years
  • Body Mass Index (BMI) of ≥27.0 kg/m2

Exclusion criteria

  • younger than 30 or 65 years or older,
  • a BMI less than 27.0 kg/m2,
  • have an allergy to any of the components in the plant-based tonic (see section 6),
  • pregnant or breastfeeding,
  • regularly skipping breakfast (i.e. not consuming breakfast on 5/7 days per week),
  • any diagnosed metabolic (e.g. diabetes), endocrine (e.g. hyperthyroidism), gastrointestinal (e.g. Crohn's) or cardiovascular (e.g. heart failure) abnormalities,
  • on an energy-restricted diet; significant weight fluctuation in the previous 3 months (>5% body weight),
  • high alcohol consumption (>14 units/week) (as per Alcohol Drink Guidelines),
  • medication that is used to treat blood glucose,
  • unable to attend in person testing sessions, or
  • unable or unwilling to provide blood samples.

Treatment and study plan

Breakfast meal challenge with tonic drink

Other

High-carbohydrate containing breakfast meal with the addition of the tonic drink

Breakfast meal challenge with placebo drink

Other

High-carbohydrate containing breakfast meal with the addition of the placebo drink

Primary outcomes

  1. 3-hour postprandial glucose incremental area under the curve

    Time frame: 3 hours

    Venous glucose concentrations measured over the 3 hour period following consumption of the breakfast meal and tonic drink/ placebo, and calculated using the trapezoid method, with T0 concentration as baseline

Secondary outcomes

  1. 3-hour postprandial insulin incremental area under the curve

    Time frame: 3-hours

    Venous insulin concentrations measured over the 3 hour period following consumption of the breakfast meal and tonic drink/ placebo, and calculated using the trapezoid method, with T0 concentration as baseline

  2. 3-hour interstitial postprandial glucose incremental area under the curve

    Time frame: 3 hours

    The interstitial glucose levels observed for the 3 hours following consumption of the breakfast meal and tonic drink/placebo using continuous glucose monitors

  3. Matsuda index (Marker of whole-body postprandial insulin sensitivity)

    Time frame: 3 hours

    This marker takes into account the 3- hour postprandial venous blood glucose and insulin measurements observed

  4. Venous blood C-peptide responses

    Time frame: 3 hours

    3-hour postprandial C-peptide responses measured in venous blood as a marker of insulin secretion

  5. Venous blood insulin to glucagon ratio's at baseline (T0) and 30 minutes (T30)

    Time frame: 30 minutes

    Ratio of venous blood insulin to glucagon at baseline and 30 minutes (T0, T30) as a marker of hepatic glucose production.

Sponsors and collaborators

Lead sponsor

Australian Catholic University

Other

Registry information

Official study title

Examining the Efficacy of a Commercially Available Multi-ingredient Liquid Tonic Drink on Postprandial Glycemia in Men and Women With Overweight and/or Obesity.

Important dates

Study start
2025
Primary completion
2025
Study completion
2026
First posted
Jun 19, 2025
Registry last updated
May 28, 2026

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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