U-shaped association between HbA1c and all-cause mortality in CVD patients with diabetes
Jianhong Yu1, Haodong Hua1, Minggang Yin2
1Department of Clinical Laboratory, Zigong First People's Hospital, Zigong, China.
Insights
Glycated hemoglobin (HbA1c) shows a U-shaped link with mortality in diabetes patients with cardiovascular disease. Optimal glycemic control, around 6.9%, may reduce all-cause mortality risk.
Area of Science:
- Cardiology
- Endocrinology
- Public Health
Background:
- Cardiovascular disease (CVD) and diabetes mellitus are leading causes of mortality worldwide.
- Glycemic control, measured by glycated hemoglobin (HbA1c), is crucial for managing diabetes.
- The relationship between HbA1c levels and mortality risk in CVD patients with diabetes requires further elucidation.
Purpose of the Study:
- To investigate the association between baseline glycated hemoglobin (HbA1c) levels and all-cause mortality in patients with diabetes and cardiovascular disease.
- To determine if this association is linear or non-linear.
- To identify an optimal HbA1c target for reducing mortality in this high-risk population.
Main Methods:
- Analysis of data from the National Health and Nutrition Examination Survey (NHANES) 1999-2014.
- Inclusion of 845 diabetic patients with cardiovascular disease, followed for a median of 7.3 years.
- Application of multivariable Cox proportional hazard models with restricted cubic splines to assess the non-linear association between HbA1c and all-cause mortality.
Main Results:
- A U-shaped relationship was observed between HbA1c levels and all-cause mortality.
- HbA1c as a continuous variable was not significantly associated with mortality.
- Patients with HbA1c levels between 6.2-7.6% had a reduced risk of mortality compared to those with levels below 6.2%. An optimal HbA1c target of 6.9% was identified.
Conclusions:
- The association between HbA1c and all-cause mortality in diabetic patients with CVD is non-linear and U-shaped.
- An HbA1c target of approximately 6.9% may be associated with the lowest mortality risk.
- Individualization of glycemic control strategies is recommended for this patient population to optimize outcomes.
Abstract:
In this analysis, the association of baseline glycated hemoglobin (HbA1c) levels with all-cause mortality in cardiovascular disease (CVD) patients with diabetes was investigated using data from NHANES 1999-2014. Under examination were 845 CVD patients who had diabetes and were followed for a median follow-up of 7.3 years, and an all-cause mortality rate of 22.60% was observed. To examine the association between HbA1c and mortality, multivariable Cox proportional hazard models using spline models determined the non-linear association. HbA1c as a continuous variable was not associated with mortality. However, a significant association was observed when HbA1c was classified according to quartiles. Particularly, after adjustment for potential confounders, in comparison to participants with HbA1c levels below 6.2%, patients with HbA1c levels of 6.2-6.8% and 6.9-7.6% had lower risks of all-cause mortality (hazard ratio: 0.49, 95% CI: 0.30-0.80 and hazard ratio: 0.64, 95% CI: 0.39-1.03, respectively). Using restricted cubic splines, further testing confirmed the lack of a linear association and instead suggested a U-shaped relationship between HbA1c and mortality, with an optimal HbA1c target value of 6.9%. A 1-unit increase in HbA1c with HbA1c less than or equal to 6.9% was predictive of a 55% reduction in all-cause mortality compared to HbA1c levels above 6.9%, which exhibited an elevation in risk. All told, these data suggest that the relationship between HbA1c and all-cause mortality in CVD patients with diabetes is non-linear and U-shaped, and therefore may suggest that individualization of glycemic control may be beneficial for this patient population.
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