Abstract
AIMS: To characterize changes in continuous glucose monitoring (CGM)-derived time in tight range (TIR) measures in individuals with prediabetes or non-insulin-treated type 2 diabetes undergoing dietary weight loss intervention and to quantify the association between weight loss and TIR improvement. METHODS: Data from the Personal Diet Study, a 6-month behavioural weight loss intervention in adults with prediabetes or non-insulin-treated type 2 diabetes [HbA(1c) ≤ 8.0% (64 mmol/mol), managed with diet alone or with metformin], was analysed. Participants wore a CGM for a maximum of 2 weeks at baseline and 6 months. Changes in overall, daytime (06:00 h-23:59 h) and overnight (00:00 h-05:59 h) time in 54-140 mg/dL or 3.0-7.8 mmol/L (TIR(54-140)), 70-140 mg/dL or 3.9-7.8 mmol/L (TIR(70-140)) and >140 mg/dL or >7.8 mmol/L (TAR(>140)) were analysed. The association between weight change and TIR change adjusted for demographic and clinical covariates was computed using linear regression. RESULTS: Baseline and 6 months CGM data from 76 participants (63 ± 8 years, 62% female, 64% White, BMI 33 ± 5 kg/m(2), HbA(1c) 5.8 ± 0.6%) were analysed. Overall TIR(54-140) increased (3.3% [0.3, 6.3]%; p = 0.03), with improvement in daytime (3.8% [0.9, 6.8]%; p = 0.01) but not overnight TIR(54-140) (2.0% [-2.2, 6.1]%; p = 0.36). In adjusted analysis, every 5% points of weight loss was associated with a 3.2% points increase in overall TIR(54-140) (p = 0.016), driven by a 3.5% points increase in daytime TIR(54-140) (p = 0.006). Similar associations were found for TAR(>140) but not TIR(70-140). There were no associations between weight loss and change in any overnight TIR measure. CONCLUSION: Weight loss was associated with improved daytime TIR(54-140) and TAR(>140) in individuals with prediabetes and non-insulin-treated type 2 diabetes undergoing dietary intervention. The daytime time in tight range measures can complement traditional markers like HbA1c, offering a more comprehensive view of glycaemic variations during dietary weight loss programmes for individuals with prediabetes and type 2 diabetes not on insulin.