When linking dietary interventions and blood glucose management, much of the existing research - particularly studies exploring the effects of vinegar - has relied on discrete readings from the conventional testing methods: blood samples or glucometers. These methods lack the capacity to provide insights into blood glucose dynamics 24/7.

Recognizing this gap, the current study aims to utilize continuous glucose monitoring to examine the impact of daily vinegar ingestion on glucose variability in adults identified as glucose intolerant.

Participants are randomly assigned to either Group A or Group B using the Microsoft Excel randomization function. Group A will be instructed to consume 4 tablespoons of red wine vinegar (2 tablespoons diluted in water at the start of the lunch and the dinner meals) for the first 4 days of the trial. Conversely, participants in Group B will ingest the placebo for the initial 4 days, ingesting one pill daily upon waking in the morning. On days 5-9, participants will switch to the opposite treatment. The red wine vinegar dosage (4 tablespoons containing 3.5 g acetic acid - this is the amount of acetic acid in a large 4-inch dill pickle), and the placebo vinegar pill dosage (one pill containing 0.022 g acetic acid) will be taken daily during the trial. On visit 1, anthropometric measurements, including height, weight, and body composition (lean fat mass and body fat mass), will be measured, and the continuous glucose monitor will be placed on the upper arm. The participants will be instructed to fast >8 hours (no food or beverages with the exception of water) ahead of visit 1. To ensure accurate use and data collection, researchers discussed the operation of CGM devices and that these waterproof devices are to be continuously worn during the entire 9-day trial and will be removed on day 9 (visit 2).

Inclusion Criteria:

• glucose intolerance (defined as one of the following: fasting glucose >99 mg/dl; diagnosis of prediabetes or diabetes; history of gestational diabetes)
• 18 years of age or older
• sedentary or moderately active (defined as a score ≤ 24 on the Godin-Shepard Leisure Time Physical Activity Questionnaire)

Exclusion Criteria:

• currently adhering to a non-typical diet that would impact carbohydrate intake (including weight loss diets)
• medication/drug use that has not been consistent for the previous 3 months or will be discontinued during the trial
• any acute illness
• regular smokers, pregnant or lactating women, or individuals taking insulin
• Unwilling to tolerate vinegar ingestion

Liquid and pill vinegar will be the treatments. The pill is the 'control' as the level of acetic acid is below the amount needed for an antiglycemic effect (a fact not realized by the participant).