Diabetes management dilemma: association between glycated hemoglobin levels and mortality risk in diabetic patients.

Abstract

Background: The relationship between improved glycemic control and mortality reduction in diabetes remains controversial. This study aimed to examine the temporal trends and association between haemoglobin A1c (HbA1c) control status and mortality risk among adults with diabetes.

Methods: This study utilized data from the National Health and Nutrition Examination Survey (NHANES) collected between 1999 and 2014. The statistical significance of linear or nonlinear trends was evaluated using logistic regression. Nonlinear temporal trends were evaluated by including quadratic terms for time in the regression models. To explore the relationships between HbA1c and mortality, the study employed the Cox proportional hazards model for multivariate analysis, along with Kaplan-Meier survival curves for univariate visualization.

Results: With 6,516 participants, the study showed a significant improvement in the control rate of HbA1c among diabetic patients, increasing from 41.61% in 1999 to 58.72% in 2014 (P<0.001). However, there was no noticeable trend in the overall all-cause mortality rate, which was 10.79% in 1999 and 12.08% in 2014 (P=0.608), or in cardiovascular mortality, which was 4.74% in 1999 and 4.24% in 2014 (P=0.371), among diabetic patients. No significant differences were found in the risks of all-cause mortality [hazard ratio (HR): 0.64; 95% confidence interval (CI): 0.36-1.13; P=0.13] or cardiovascular mortality (HR: 1.11; 95% CI: 0.41-3.02; P=0.84) between patients with HbA1c below 7.0% and those with HbA1c 7.0% or higher. Interestingly, the rate of sulfonylureas use went down from 30.25% in 1999 to 12.42% in 2014 (linear P value <0.001).

Conclusions: Despite significant improvements in HbA1c control rates among US adults with diabetes from 1999 to 2014, we observed no corresponding reduction in 5-year mortality risks. Achieving HbA1c <7.0% was not associated with lower mortality risk in this population. These findings suggest that improvements in glycemic control alone may be insufficient to reduce mortality in diabetic populations, highlighting the need for a more comprehensive approach to diabetes management.