INS and diabetes mellitus: As the results indicated, insulin treatment was a significant positive predictor of IAA (OR = 5.20, 95%CI 2.96–9.14, p < 0.0001) after adjusted for BMI, duration of diabetes, and postprandial C peptide, while level of fasting C peptide was a significant negative predictor of GADA (OR = 0.52, 95%CI 0.30–0.91, p = 0.02) with correction for BMI, FBG, and postprandial C peptide.