Routine HbA1c monitoring and cardiovascular outcomes in diabetes: Evidence from a large Spanish cohort
Domingo Orozco-Beltran1, Samuel Seidu2, Jose Antonio Quesada3
1Primary Care Research Center CIAP, Department of Clinical Medicine, University of Miguel Hernández Elche, Comunidad Valenciana, Spain.
Insights
Missing glycated hemoglobin (HbA1c) values in diabetes patients are linked to a more than doubled risk of cardiovascular events or death. This highlights the importance of routine HbA1c monitoring for prognosis.
Area of Science:
- Endocrinology and Metabolism
- Cardiovascular Health
- Health Informatics
Background:
- Glycated hemoglobin (HbA1c) is crucial for monitoring diabetes control.
- The clinical implications of missing HbA1c values in patient records are not well understood.
- Understanding missing data risks is vital for accurate patient outcome prediction.
Purpose of the Study:
- To investigate the association between missing HbA1c values and major adverse cardiovascular events or all-cause mortality.
- To analyze the prognostic significance of unrecorded HbA1c levels in individuals with diabetes.
- To evaluate the risk stratification potential of complete versus incomplete HbA1c data.
Main Methods:
- Retrospective cohort study utilizing the Spanish BIFAP primary care electronic medical records database.
- Inclusion of individuals aged 30+ with incident diabetes mellitus, followed from diagnosis (2005-2019) until an endpoint event or end of study (Dec 31, 2019).
- Analysis employed Cox models, comparing risks across HbA1c categories: <7%, 7%-8%, >8%, and missing.
Main Results:
- The study included 303,199 diabetes patients (mean age 62.2 years, 44.7% female) with a mean follow-up of 5.7 years.
- A significant proportion (10.2%) of patients had missing HbA1c values at baseline.
- Missing HbA1c was associated with a substantially elevated risk (HR 2.95; 95% CI: 2.89-3.05) compared to HbA1c <7%.
Conclusions:
- Missing HbA1c values in newly diagnosed diabetes patients indicate a significantly higher risk of major cardiovascular events and death.
- The risk associated with missing HbA1c is more than double that of patients with the poorest glycemic control (HbA1c >8%).
- Routine HbA1c recording and monitoring are essential not only for metabolic assessment but also as a prognostic indicator, potentially signaling suboptimal clinical care.
Aim:
Glycated hemoglobin (HbA1c) is a key indicator of diabetes control. However, the risk of missing HbA1c values in clinical records is unknown. We aimed to analyze the relationship between missing HbA1c values and the occurrence of major cardiovascular events or death from all causes.
Methods:
Retrospective cohort study based on a national database of primary care electronic medical records in Spain (BIFAP). We included people aged 30 years and older with an incident diagnosis of diabetes mellitus. Follow-up started on the date of diabetes diagnosis between 2005 and 2019, and ended on occurrence of composite endpoint (major cardiovascular events and/or death from all causes), or December 31st, 2019. The baseline exposure variable was HbA1c (< 7 %, 7 %-8 %, > 8 %, missing). Cox models were fitted.
Results:
Our analysis included 303,199 people with diabetes, with an average age of 62.2 years and 44.7 % were women. The mean follow-up was 5.7 years, and 10.2 % of patients had missing HbA1c values. The cardiovascular risk was 1.18 (95 %CI: 1.14-1.22) in the HbA1c 7 %-8 % group, 1.41 (95 %CI: 1.36-1.46) in HbA1c > 8 %, and 2.95 (95 %CI: 2.89-3.05) in HbA1c missing, compared with HbA1c < 7 %.
Conclusions:
In this large cohort of people with newly diagnosed diabetes, missing HbA1c values was associated with a significantly higher risk of major cardiovascular events or death, more than double the risk observed in people with the worst glycemic control. These findings underscore the clinical importance of routinely recording and monitoring HbA1c at diagnosis, not only as a marker of metabolic control but also as a potential prognostic indicator. The lack of HbA1c may act as an indicator of suboptimal clinical follow-up.
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