Different Aerobic-to-Resistance Training Ratios in Adults Aged 50 Years and Older With Prediabetes

The goal of this clinical trial is to evaluate how different time ratios of aerobic and resistance training affect blood glucose levels and physical health in adults aged 50 years and older with prediabetes. Researchers will compare three combined exercise programs with aerobic-to-resistance training time ratios of 3:1, 1:1, and 1:3 with a health education control group. Participants in the exercise groups will take part in supervised training three times per week for 12 weeks. Each session will include approximately 60 minutes of aerobic and resistance exercise, with the amount of time spent on each type of exercise differing according to the assigned group. Participants will complete health assessments before and after the 12-week intervention. The main outcome of interest is glycated hemoglobin (HbA1c), which reflects average blood glucose levels over the previous 2 to 3 months. Participants in the control group will receive standardized health education and will not take part in the study-provided structured exercise program during the 12-week intervention period.

Inclusion Criteria: * Age 50 years or older. * Body mass index (BMI) of 24.0 to 32.5 kg/m². * Prediabetes, defined by at least one of the following: fasting plasma glucose of 5.6-6.9 mmol/L, 2-hour plasma glucose of 7.8-11.0 mmol/L during a 75-g oral glucose tolerance test, or glycated hemoglobin (HbA1c) of 5.7%-6.4%, without meeting diagnostic criteria for diabetes. * Not regularly meeting recommended exercise levels during the previous 3 months, defined as less than 150 minutes per week of moderate-intensity aerobic activity or an equivalent amount of moderate-to-vigorous aerobic activity, and resistance training on fewer than 2 days per week. * Able to perform activities of daily living independently and considered medically suitable to participate safely in moderate-intensity aerobic and resistance exercise. * Able to participate in the 12-week intervention and major study assessments. * Able to understand the study procedures and provide written informed consent. Exclusion Criteria: * Previously diagnosed diabetes, or diabetes-range glucose results at formal baseline screening confirmed by medical assessment. * Regular use within the previous 3 months of medications that may substantially affect glucose metabolism, body weight, or the primary outcome, including glucose-lowering medications, weight-loss medications, or systemic glucocorticoids. * Severe, acute, or inadequately controlled medical conditions that, in the judgment of the study medical team, would make exercise participation or exercise testing unsafe. * Severe musculoskeletal, neurological, cognitive, or psychiatric conditions that would interfere with safe participation in the intervention or study assessments. * Alcohol Use Disorders Identification Test (AUDIT) score ≥16, or clinically significant harmful alcohol use or alcohol dependence based on medical assessment. * Unintentional body weight change greater than 5% during the previous 6 months, or current participation in another structured intervention likely to substantially affect glucose metabolism, body weight, or physical activity. * Pregnancy, breastfeeding, planned pregnancy during the study period, or other circumstances expected to prevent completion of the 12-week intervention and primary outcome assessment.