Participants and randomization
diabetes
DISEASES, DIABETES
The participants between 18 and 70 years of age who received a diagnosis of diabetes according to 1999 World Health Organization (WHO) criteria at 18 years or older within 4 years, and were initially positive for GADA, had a fasting C-peptide level of at least 100 pmol/L or 2-h postprandial C-peptide level of at least 200 pmol/L after MMTT, were eligible for participation in the trial. Participants who received DPP-4 inhibitors, GLP-1 analogues, GLP-1 receptor agonists and thiazolidinediones within 8 weeks prior to randomization and had a medical history of other clinically significant diseases were excluded.Participants were randomly assigned 1:1:1 by a central randomization system to receive metformin with or without insulin (conventional therapy), saxagliptin alone or saxagliptin plus vitamin D as add-on drugs to conventional therapy. Randomization was stratified by the fasting C-peptide (<300 pmol/L or ≥300 pmol/L), GADA level (<180 or ≥180 U/mL)