Objective:To explore the correlation between time in range (TIR) after short-term treatment and glycated hemoglobin after 3 months (HbA lc-3m) in patients with newly-diagnosed type 2 diabetes mellitus (T2DM). Methods:In this cross-sectional study, a total of 94 patients with newly-diagnosed T2DM who received treatment in the Department of Endocrinology of Inner Mongolia Autonomous Region People′s Hospital were enrolled from January 2018 to September 2022. The patients were followed-up for 3 months and had complete medical record. TIR was divided into three groups according to different target ranges of blood glucose (TIR1: TIR with blood glucose between 3.9 and 10.0 mmol/L, TIR2: TIR with blood glucose between 3.9 and 7.8 mmol/L, TIR3: TIR with fasting, premeal or bedtime blood glucose <6.1 mmol/L and 2 h postprandial blood glucose <8.0 mmol/L). The patients were divided into two groups based on whether their HbA 1c-3m level was less than 6.5%, and the baseline data and variations in TIR for distinct target glucose levels were compared between the two groups. Spearman′s correlation analysis and binary logistic regression analysis were used to analyze the relationship between baseline indicators, TIR after short-term treatment and HbA 1c-3m. Receiver operating characteristic curve (ROC) was drawn to evaluate the predictive ability of different TIR after short-term therapy for HbA 1c-3m. Results:There were statistically significant differences in TIR1 [81.0 (67.5, 94.6)% vs 71.4 (51.7, 85.7)%], TIR2 [57.7 (29.7, 70.8)% vs 40.9 (22.4, 52.3)%] and TIR3 [23.8 (10.2, 39.5)% vs 13.0 (4.8, 25.0)%] between patients with a HbA 1c-3m<6.5% and patients with a HbA 1c-3m≥6.5% (all P<0.05). Spearman correlation analysis showed that among all the patients with newly-diagnosed T2DM, TIR1, TIR2 and TIR3 were all negatively correlated with HbA 1c-3m [6.4 (6.1, 6.9)%] ( r=-0.322, -0.348, -0.303, respectively, all P<0.01). Logistic regression analysis showed that after adjusting for the confounding factors, TIR1 ( OR=1.021, 95% CI: 1.002-1.041; P=0.034), TIR2 ( OR=1.024, 95% CI: 1.006-1.043; P=0.011), TIR3 ( OR=1.037, 95% CI: 1.010-1.065; P=0.008) were all independently related to HbA 1c-3m. When HbA lc-3m<6.5% was taken as the target value, the area under the ROC curve: TIR1 was 0.639 (95% CI: 0.528-0.751), TIR2 was 0.671 (95% CI: 0.560-0.782), TIR3 was 0.659 (95% CI: 0.549-0.770), respectively. When HbA lc-3m<7.0% was taken as the target value, the area under the ROC curve: TIR1 was 0. 730 (95% CI: 0.619-0.841), TIR2 was 0.744 (95% CI: 0.642-0.846), TIR3 was 0.701 (95% CI: 0.588-0.814). There was no significant difference in the area among the three statistics ( P>0.05). Conclusions:For newly-diagnosed T2DM patients, TIR after short-term treatment is negatively correlated with HbA 1c after 3 months and has good predictive value for it.