Effects of a Mediterranean Diet With Cycling and Rowing Exercise on Blood Sugar in Women With Prediabetes

NCT07326891 | Enrolling By Invitation DMC

• 1 other identifier: 09.2022.946
• Study Type: interventional
• Target: 30
• Locations: 1 country
• Sites: 1

Brief Summary

The goal of this clinical trial is to learn how a Mediterranean-style diet, with and without added exercise, affects blood sugar control in women with prediabetes. Prediabetes means blood sugar levels are higher than normal but not yet type 2 diabetes. Healthy eating and regular physical activity can help prevent diabetes. The investigators aim to answer two main questions:

• Group 1 (Diet only): Will follow a Mediterranean eating plan for 12 weeks.
• Group 2 (Diet + Exercise, Current High Blood Sugar): Will follow the same diet and also do supervised exercise (cycling, then rowing) three times a week for 8 weeks.
• Group 3 (Diet + Exercise, Recent Normal Blood Sugar): Will follow the same diet and exercise program as Group 2. These women had prediabetes in the past year but now have normal blood sugar levels. All participants will follow the study protocol for 12 weeks, which includes the following key components:
• Dietary Intervention: Adherence to a Mediterranean-style eating plan, which emphasizes high intake of vegetables, fruits, whole grains, legumes, olive oil, and fish.
• Continuous Glucose Monitoring: Wearing a continuous glucose monitoring (CGM) device-a small, minimally invasive sensor placed on the upper arm-during multiple 10-day periods. This device tracks interstitial glucose levels throughout the day and night to assess daily glucose patterns.
• Blood Sampling and Analysis: Providing fasting blood samples for the measurement of glycemic and metabolic health markers. These include fasting plasma glucose, hemoglobin A1c (HbA1c), fasting insulin, and 2-hour oral glucose tolerance test (OGTT) results.
• Anthropometric Assessments: Undergoing standardized measurements of height, body weight, body fat percentage (via bioelectrical impedance), waist circumference, and Body Mass Index (BMI) at scheduled intervals.
• Questionnaires: Completing validated surveys to assess habitual dietary intake, sleep quality and duration, and levels of physical activity. Investigators will compare changes in blood sugar control and other health measures from the start to the end of the 12-week study among the three groups.

Conditions

Prediabetes

Keywords

Prediabetes; Continuous Glucose Monitoring; Mediterranean Diet; Glycaemic Variability; Aerobic Exercise

Outcome Measures

Primary Outcomes (4)

• Change in Fasting Plasma Glucose (FPG)

  Change in Fasting Plasma Glucose levels, measured in mg/dL from venous blood.

  Baseline (week 0) and the end of the 12 weeks program (week 13)

• Change in 2-hour Oral Glucose Tolerance Test (OGTT) Glucose

  Change in plasma glucose levels measured 2 hours after a standardized glucose load, measured in mg/dL from venous blood.

  Baseline (week 0) and the end of the 12 weeks program (week 13)

• Change in Hemoglobin A1c (HbA1c)

  Change in the percentage (%) of glycated hemoglobin (HbA1c) measured from venous blood.

  Baseline (week 0) and the end of the 12 weeks program (week 13)

• Change in Fasting Insulin

  Change in fasting serum insulin levels, measured in microinternational units per milliliter (µIU/mL) from venous blood. This measurement serves as an indicator of basal insulin secretion and insulin resistance.

  Baseline (week 0) and the end of the 12 weeks program (week 13)

Secondary Outcomes (15)

• Change in Body Weight

  Baseline (Week 0), Weeks 2, 4, 6, 8, 10, and 12.

• Change in Body Mass Index (BMI)

  Baseline (Week 0), Weeks 2, 4, 6, 8, 10, and 12.

• Change in Body Fat Percentage

  Baseline (Week 0), Weeks 2, 4, 6, 8, 10, and 12.

• Change in Waist-to-Hip Ratio

  Baseline (Week 0), Weeks 2, 4, 6, 8, 10, and 12.

• Change in Glycemic Variability (CV)

  Exercise groups: Baseline (week 2) , Week 6, Week 10 and Week 13. Control group: Baseline (week 2) and Week 13.

Study Arms (3)

Control Group

ACTIVE COMPARATOR

Women with medically documented prediabetes who are not eligible for the supervised exercise program for medical reasons. This arm serves as the primary comparison group and represents standard care. Participants will follow a 12-week individualized Mediterranean diet intervention emphasizing high intake of vegetables, fruits, whole grains, legumes, nuts, and olive oil; moderate consumption of fish and poultry; and low intake of red meat, processed foods, and sweets. Dietary counseling will be provided by a dietitian, and participants will complete food diaries. All participants will undergo the same scheduled assessments as the intervention arms, including blood tests, anthropometric measurements, questionnaires, and continuous glucose monitoring (CGM).

Other: Mediterranean Diet

Active Prediabetes Exercise Group

EXPERIMENTAL

Women with active prediabetes who are medically eligible for exercise will participate in a 12-week intervention including a Mediterranean-style diet throughout the study and a supervised 8-week sequential exercise program between Weeks 3 and 10. The exercise program will consist of cycling ergometer training during Weeks 3-6 and rowing ergometer training during Weeks 7-10. Participants will complete three supervised sessions per week, each lasting approximately 51 minutes. Exercise intensity will be individualized using the Heart Rate Reserve (HRR) method, based on resting heart rate and maximal heart rate measured by a maximal Bruce protocol test. Each session will include a warm-up at 40% HRR, alternating intervals at 50% and 60% HRR with short recovery periods, and a cool-down at 40% HRR. Heart rate will be continuously monitored using a Polar H10 chest strap.

Other: Mediterranean Diet; Behavioral: Supervised Sequential Exercise

Remission Prediabetes Exercise Group

EXPERIMENTAL

Participants in this arm are women with a documented diagnosis of prediabetes within the past year who are normoglycemic at screening according to American Diabetes Association (ADA) criteria and are medically eligible to participate in exercise. These participants will receive the same 12-week Mediterranean diet program and the same supervised 8-week sequential exercise intervention (cycling followed by rowing) as the active prediabetes exercise group.

Other: Mediterranean Diet; Behavioral: Supervised Sequential Exercise

Interventions

Mediterranean Diet OTHER

This is a 12-week personalised dietary intervention based on the Mediterranean diet, structured around four daily meals. It emphasises a high intake of vegetables, fruits, whole grains, legumes, nuts and olive oil, as well as moderate consumption of fish and poultry, and a low intake of red meat, processed foods and sweets. Participants receive individual counselling sessions with a dietitian every two weeks and are required to keep a daily food diary to monitor adherence and provide feedback.

Active Prediabetes Exercise Group; Control Group; Remission Prediabetes Exercise Group

Supervised Sequential Exercise BEHAVIORAL

An 8-week, supervised, sequential aerobic exercise program. Participants attend three sessions per week. The first 4 weeks consist of cycling ergometer sessions, followed by 4 weeks of rowing ergometer sessions. Exercise intensity is personalized using Heart Rate Reserve (HRR) based on directly measured maximum heart rate from a baseline cardiopulmonary exercise test. Sessions are supervised by an exercise physiologist.

Active Prediabetes Exercise Group; Remission Prediabetes Exercise Group

Eligibility Criteria

• Age: 22 Years - 55 Years
• Sex: female
• Healthy Volunteers: No
• Age Groups: Adult (18-64)

You may qualify if:

• Having a diagnosis of prediabetes (within the last 1 year)
• Impaired Fasting Glucose (IFG) 100-125 mg/dl
• OGTT result 2-hour postprandial Impaired Glucose Tolerance (IGT) 140-199 mg/dl
• HbA1c 5.7-6.4%
• Being between 22-55 years of age
• Being female
• Body Mass Index 18-34.9 kg/m2
• Meeting the criteria in the American College of Sports Medicine (ACSM) and American Heart Association (AHA) cardiovascular disease risk assessment scoring system
• Not engaging in regular planned exercise or physical activity (sedentary)

You may not qualify if:

• Diabetes
• Being pregnant
• No self-reported low iron concentrations or anaemia
• Use of medication, insulin, or weight loss injections known to affect lipid and glucose metabolism
• Presence of cardiovascular disease
• Current smoking or excessive alcohol consumption
• Presence of abnormal electrocardiogram (ECG)
• Presence of autonomic neuropathy
• Presence of uncontrolled hypertension (systolic blood pressure \>135 mmHg, diastolic blood pressure \>85 mmHg)
• Joint-muscle-bone injury limiting exercise

Sponsors & Collaborators

• Begüm Yücesoy Güneysu: lead
• Marmara University: collaborator
• Marmara University Pendik Training and Research Hospital: collaborator
• Goztepe Prof Dr Suleyman Yalcın City Hospital: collaborator

Study Sites (1)

Marmara University

Beykoz, Istanbul, Turkey (Türkiye)

Location

MeSH Terms

Conditions

Prediabetic State

Interventions

Diet, Mediterranean

Condition Hierarchy (Ancestors)

Diabetes Mellitus; Glucose Metabolism Disorders; Metabolic Diseases; Nutritional and Metabolic Diseases; Endocrine System Diseases

Intervention Hierarchy (Ancestors)

Diet, Plant-Based; Diet Therapy; Nutrition Therapy; Therapeutics; Diet; Nutritional Physiological Phenomena; Diet, Food, and Nutrition; Physiological Phenomena

Study Officials

• Hasan Birol Çotuk, Prof.

  Turkish-German University

  STUDY DIRECTOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NON RANDOMIZED
• Masking: SINGLE
• Who Masked: OUTCOMES ASSESSOR
• Masking Details: Due to the behavioral nature of lifestyle interventions (supervised exercise and diet counseling), it will not be possible to blind participants or personnel administering the interventions. However, the data analyst performing the statistical analyses will be unaware of information regarding group assignment. Analysis datasets will be anonymized with neutral codes before being provided to the analyst.
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR INVESTIGATOR
• PI Title: PhD(c), Dietitian, Principal Investigator

Model Details: This is a non-randomized, three-arm, parallel-group study. Participants are allocated to one of three groups based on their glycemic status and medical eligibility for exercise: 1) Control: Mediterranean diet only (active prediabetes, exercise-ineligible); 2) Intervention Group 1: Mediterranean diet + sequential exercise (active prediabetes); 3) Intervention Group 2: Mediterranean diet + sequential exercise (prediabetes in remission). The primary scientific comparison is between the two exercise groups (Group 2 vs. Group 3) to assess the influence of baseline metabolic phenotype on intervention response.

Study Record Dates

• First Submitted: December 22, 2025
• First Posted: January 8, 2026
• Study Start: December 15, 2025
• Primary Completion (Estimated): July 1, 2026
• Study Completion (Estimated): December 1, 2026
• Last Updated: January 8, 2026

Record last verified: 2025-12

Locations

TU (1)