Impact of time in tight range on all-cause and cardiovascular mortality in type 2 diabetes: A prospective cohort study.

Aims: Currently, there is a lack of evidence regarding time in tight range (TITR) and long-term adverse outcomes. We aimed to investigate the association between TITR and the risk of all-cause and cardiovascular mortality among patients with type 2 diabetes.

Materials And Methods: A total of 6061 patients with type 2 diabetes were prospectively recruited in a single centre. TITR was measured with continuous glucose monitoring (CGM) at baseline and was defined as the percentage of time in the target glucose range of 3.9-7.8 mmol/L (70-140 mg/dL) during a 24-h period. Cox proportion hazard regression models were used to examine the association between TITR and the risk of all-cause and cardiovascular mortality.

Results: During a median follow-up period of 10.9 years, 1898 (31.3%) death events were confirmed, with 689 (11.4%) due to cardiovascular mortality. The restricted cubic spline revealed significant linear relationships between lower TITR and higher risks of all-cause and cardiovascular mortality (p for linearity <0.01). In the fully adjusted model including glycated haemoglobin A1c, each 10% decrease in TITR was associated with 4% (95% confidence interval, 1.01-1.06) increased risk of all-cause mortality and 4% (95% confidence interval, 1.00-1.08) increased risk of cardiovascular mortality. Subgroup analyses showed that the linear relationship between TITR and all-cause mortality risk was sustained in patients with haemoglobin A1c <7.0% and patients with fasting plasma glucose <7.0 mmol/L.

Conclusions: Lower TITR is associated with an increased risk of all-cause and cardiovascular mortality in patients with type 2 diabetes, indicating that tight glycaemic control within the physiological range may be crucial for reducing long-term mortality risk, especially in those with seemingly well-controlled diabetes.