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:
1. Does adding a supervised program of cycling and rowing exercises to the diet lead to better blood sugar control than the diet alone? 2. Do women who recently returned to normal blood sugar levels respond differently to the exercise program than those who currently have high blood sugar?
Participants will be placed into one of three groups based on current blood sugar levels and medical fitness for exercise:
* 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.
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%
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
Parallel
Mediterranean Diet
Other interventionThis 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.
Supervised Sequential Exercise
BehavioralAn 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.
Change in Fasting Plasma Glucose (FPG)
Change in Fasting Plasma Glucose levels, measured in mg/dL from venous blood.
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.
Change in Hemoglobin A1c (HbA1c)
Change in the percentage (%) of glycated hemoglobin (HbA1c) measured from venous blood.
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.
Change in Body Weight
Change in body weight measured in kilograms (kg).
Change in Body Mass Index (BMI)
Weight and height measurements will be combined to report Body Mass Index in kilograms per square meter (kg/m²), calculated as weight (kg) / \[height (m)\]².
Change in Body Fat Percentage
Change in total body fat measured as a percentage (%).
Change in Waist-to-Hip Ratio
Waist and hip circumference measurements (in centimeters) will be combined to calculate and report the Waist-to-Hip Ratio. The ratio is calculated as Waist Circumference (cm) / Hip Circumference (cm) and is a unitless value. Changes in this ratio will be assessed.
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Begüm Yücesoy Güneysu
Lead sponsor
Marmara University
Sponsor institution
Marmara University
Collaborator
Marmara University Pendik Training and Research Hospital
Collaborator
Goztepe Prof Dr Suleyman Yalcın City Hospital
Collaborator
