Association between glycated hemoglobin and risk of all-cause mortality in community patients with type 2 diabetes: A prospective cohort study

Aims/Introduction: To analyze the association between HbA1c level and the risk of all-cause mortality in community patients with type 2 diabetes mellitus, and to provide a scientific basis for the management of type 2 diabetes mellitus in the community. Materials and Methods: Based on a Zhejiang rural community type 2 diabetes mellitus cohort, a total of 10,310 patients with type 2 diabetes mellitus with complete baseline and follow-up data were selected. The Cox proportional hazards regression model and the restricted cubic spline model were used to evaluate the relationship between the HbA1c level and the risk of all-cause mortality. Results: During a mean follow-up of 5.5 years, 971 patients died. With HbA1c levels of 6.5-7.0% as the reference, after adjusting for relevant confounding factors, the HR(95%CI) of all-cause mortality with HbA1c levels of <5.5%, 5.5-6.5%, 7.0-8.0%, 8.0-9.0%, and >= 9.0% were 1.53 (1.08-2.15), 0.97 (0.79-1.21), 1.14 (0.92-1.41), 1.44 (1.14-1.83), and 2.08 (1.68-2.58), respectively. The HbA1c level was associated with the risk of all-cause mortality in a "J-shaped" manner. The risk of all-cause mortality was lowest when the HbA1c was 6.5-7.0%, and increased significantly when the HbA1c was >= 8.0% and the HbA1c was < 5.5% (P < 0.05). The risk of all-cause death in the HbA1c 5.5-6.5% group and the 7.0-8.0% group was not significant compared with the reference group (P > 0.05). Conclusions: The HbA1c levels were associated with the risk of all-cause mortality in type 2 diabetes mellitus in a "J-shaped" manner, a too high or a too low HbA1c level could increase the risk of death. Attention should be paid to the individual evaluation of patients and the setting of appropriate glycemic control goals.