The effect of aerobic and resistance training in patients with type 2 diabetes on vitamin D (DIAVITEX): a study protocol

Introduction: Aerobic and resistance training can effectively improve clinical management in people with type 2 diabetes (T2D). Low vitamin D (VitD) levels are associated with T2D risk and metabolic disturbances, and may help reduce this risk, particularly in individuals with low VitD levels. In this line, many individuals with T2D, who may also be older adults or have osteoporosis, regularly include VitD treatment in their healthcare routines. Although the impact of exercise has been extensively studied, its effect on diabetic patients taking VitD remains limited. The aim of this study is to investigate the effect of aerobic and resistance training on clinical parameters in patients with T2D already taking VitD. Methods: The DIAVITEX study is a randomized controlled superiority trial, with four parallel arms, including 80 individuals with T2D. Patients will be selected at the Primary Care Centers and stratified according to their pre-existing VitD treatment. Participants will subsequently be randomized to the exercise intervention or control as follows: Group 1, Exercise + VitD users (n = 20); Group 2, Exercise + VitD non-users (n = 20); Group 3, VitD only (no exercise) (n = 20); and Group 4, Control (No VitD & No Exercise) (n = 20). In this study, a sarcoplasm-stimulating training program will be carried out online, three sessions per week for a total of 16 weeks. Before and after the physical activity subjects will perform fitness and blood tests. Nutritional education programs will be provided to normalize their diets for study consistency. The primary endpoint of the trial is the change in HOMA-IR index from baseline to week 16. Secondary endpoints include changes in HbA1c, lipid profile, body composition, and inflammatory biomarkers. Discussion: Expected improvements in insulin resistance, glycated hemoglobin, lipid profile, and inflammatory markers are anticipated following a 16-week regimen of exercise in patients with T2D on VitD. Clinical trial registration: The study was registered on September 21, 2024, with the identifier number NCT06081387, https://clinicaltrials.gov/study/NCT06081387.