Time in range in relation to all-cause and cardiovascular mortality in patients with type 2 diabetes: a prospective cohort study

Objective: There is growing evidence linking time in range (TIR), an emerging metric for assessing glycemic control, to diabetes-related outcomes. We aimed to investigate the association between TIR and mortality in patients with type 2 diabetes.

Research design and methods: A total of 6225 adult patients with type 2 diabetes were included from January 2005 to December 2015 from a single center in Shanghai, China. TIR was measured with continuous glucose monitoring at baseline, and the participants were stratified into 4 groups by TIR: >85%, 71-85%, 51-70%, and ≤50%. Cox proportional hazards regression models were used to estimate the association between different levels of TIR and the risks of all-cause and cardiovascular disease (CVD) mortality.

Results: The mean age of the participants was 61.7 years at baseline. During a median follow-up of 6.9 years, 838 deaths were identified, 287 of which were due to CVD. The multivariable-adjusted hazard ratios associated with different levels of TIR (>85% [reference group], 71-85%, 51-70%, and ≤50%) were 1.00, 1.23 (95% CI, 0.98-1.55), 1.30 (95% CI, 1.04-1.63), and 1.83 (95% CI, 1.48-2.28) for all-cause mortality (P for trend <0.001), and 1.00, 1.35 (95% CI, 0.90-2.04), 1.47 (95% CI, 0.99-2.19), and 1.85 (95% CI, 1.25-2.72) for CVD mortality (P for trend =0.015), respectively.

Conclusions: The present study indicated an association of lower TIR with an increased risk of all-cause and CVD mortality among patients with type 2 diabetes, supporting the validity of TIR as a surrogate marker of long-term adverse clinical outcomes.