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Relationship between hemoglobin A1c and cardiovascular disease in mild-to-moderate hypercholesterolemic Japanese
Rimei Nishimura1, Tomoko Nakagami, Hirohito Sone
1Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Jikei University School of Medicine, 3-25-8 Nishi-Shinbashi, Minato-ku, Tokyo 105-8461, Japan. rimei@yahoo.co.jp
Insights
Elevated hemoglobin A1c (HbA1c) significantly increases cardiovascular disease (CVD) risk in hypercholesterolemic individuals. Managing HbA1c is crucial for CVD prevention, independent of cholesterol treatment.
Area of Science:
- Cardiology
- Endocrinology
- Metabolic Diseases
Background:
- The ADA/EASD/IDF recommends hemoglobin A1c (HbA1c) for diabetes diagnosis.
- The relationship between HbA1c and cardiovascular disease (CVD) in hypercholesterolemia requires further investigation.
- This study analyzes HbA1c and CVD risk in Japanese hypercholesterolemic patients.
Purpose of the Study:
- To investigate the association between HbA1c levels and the incidence of CVD.
- To determine if this association is influenced by sex, LDL-C, or pravastatin treatment.
- To understand the role of HbA1c in CVD risk among hypercholesterolemic individuals.
Main Methods:
- Subanalysis of the MEGA Study involving 4002 hypercholesterolemic patients (aged 40-70).
- Patients were stratified based on average HbA1c levels (<6.0%, 6.0%-<6.5%, ≥6.5%) during the first year.
- Subsequent 5-year CVD incidence rates were compared across strata, considering sex, LDL-C, and treatment (diet alone vs. diet plus pravastatin).
Main Results:
- Individuals with HbA1c ≥ 6.5% had a 2.4-fold higher CVD risk compared to those with HbA1c <6.0%.
- This increased risk was consistent across sexes and independent of the treatment arm (diet or pravastatin).
- Continuous risk increase was observed with rising HbA1c levels, as shown by spline curves.
Conclusions:
- Cardiovascular disease risk escalates linearly with HbA1c levels in hypercholesterolemic patients.
- Elevated HbA1c is a significant, independent predictor of CVD risk.
- Effective HbA1c management is essential alongside lipid reduction for comprehensive CVD prevention.
Background:
Although the ADA/EASD/IDF International Expert Committee recommends using hemoglobin A1c (HbA1c) to define diabetes, the relation between HbA1c and cardiovascular disease (CVD) has not been thoroughly investigated. We analyzed this relation using clinical data on Japanese individuals with hypercholesterolemia.
Methods:
In the large-scale MEGA Study 7832 patients aged 40 to 70 years old with mild-to-moderate hypercholesterolemia without CVD were randomized to diet alone or diet plus pravastatin and followed for >5 years. In the present subanalysis of that study a total of 4002 patients with baseline and follow-up HbA1c data were stratified according to having an average HbA1c during the first year of follow-up <6.0%, 6.0%-<6.5%, or ≥ 6.5% and their subsequent 5-year incidence rates of CVD compared according to sex, low-density lipoprotein cholesterol (LDL-C), and treatment arm.
Results:
Overall, risk of CVD was significantly 2.4 times higher in individuals with HbA1c ≥ 6.5% versus <6.0%. A similar relation was noted in men and women (hazard ratio [HR], 2.1; p <0.01 and HR, 3.0; p <0.01, respectively) and was regardless of treatment arm (diet alone group: HR, 2.2; p <0.001; diet plus pravastatin group: HR, 1.8; p = 0.02). Spline curves showed a continuous risk increase according to HbA1c level in all subpopulations studied.
Conclusions:
In hypercholesterolemic individuals the risk of CVD increases linearly with HbA1c level. This significant contribution by elevated HbA1c to increased CVD is independent of pravastatin therapy, and thus requires appropriate HbA1c management in addition to lipids reduction.
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