2.1. Study Design and Population
fracture, T2DM, hypoglycemic
ACUTE INFECTION, OSTEOPOROSIS, RENAL INSUFFICIENCY
The study was a randomized controlled trial with a 12-week intervention and additional 12-week follow-up period assessing the impact of vitamin D and exercise intervention on glycemic improvement in participants diagnosed with T2DM without insulin treatment in Xi’an, China (34° N latitude). Participants were excluded if they had (a) past insulin therapy or a plan to change hypoglycemic drugs during the trial; (b) ≥400 IU/day vitamin D supplementation for a month or regular exercise training; (c) acute infection; stress; heart, liver, and renal insufficiency; osteoporosis; or fracture; (d) a history of sunbathing at the beach, at a swimming pool, or anywhere else in the last six months; or (e) use of metal implants or other factors that could influence dual-energy X-ray absorptiometry (DXA) testing. Participants were randomly allocated into four groups using a computer-generated random number sequence: exercise + vitamin D group (EX + VD: Based on our previous study examining the association of vitamin D intervention with HOMA-IR [All of the procedures were reviewed and approved by the Ethics Committee of Xi’an Jiaotong University Health Science Center. The study was conducted in accordance with the Declaration of Helsinki and registered in the Chinese Clinical Trial System (No. ChiCTR1800015383).