Appendix_TIR_manuscript_04202021.pdf (348.34 kB)

Increased Hemoglobin A1c Time in Range Reduces Adverse Health Outcomes in Older Adults With Diabetes

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posted on 15.06.2021, 07:05 by Julia C. Prentice, David C. Mohr, Libin Zhang, Donglin Li, Aaron Legler, Richard E. Nelson, Paul R. Conlin
Objective: Short and long-term glycemic variability are risk factors for diabetes complications. However, there are no validated A1c target ranges or measures of A1c stability in older adults. We evaluated the association of a patient-specific A1c variability measure, A1c time in range (A1c TIR), on major adverse outcomes.

Research Design and Methods: We conducted a retrospective observational study using administrative data from the Department of Veterans Affairs and Medicare from 2004 - 2016. Patients were ≥65 years old with diabetes and at least four A1c tests during a three-year baseline period. A1c TIR was the percentage of days during the baseline in which A1c was in an individualized target range (from 6.0-7.0% up to 8.0-9.0%) based on clinical characteristics and predicted life expectancy. Increasing A1c TIR was divided into categories of 20% increments and linked to mortality and cardiovascular disease (CVD) (i.e. myocardial infarction [MI] and stroke).

Results: The study included 402,043 Veterans (mean [SD] age, 76.9 [5.7] years; 98.8% male). During an average of 5.5 years of follow-up, A1c TIR had a graded relationship with mortality and CVD. Cox proportional hazards models showed lower A1c TIR was associated with increased mortality (A1c TIR 0-<20%; Hazard Ratio (HR) = 1.22; 95% CI, 1.20-1.25) and CVD (A1c TIR 0-<20%; HR = 1.14; 95% CI, 1.11-1.19) when compared to A1c TIR 80-100%. Competing risk models and shorter follow-up (e.g. 24 months) showed similar results.

Conclusion: In older adults with diabetes, maintaining A1c levels within individualized target ranges is associated with lower risk of mortality and CVD.


Supported by the Department of Veterans Affairs, Veterans Health Administration, Office of Research and Development, Health Services Research and Development (IIR 15-116) and the National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases (R01 DK114098). Data were obtained with support from VA Information Resource Center (VIRReC), VA/CMS Data for Research Project, SDR 02-23.