This article is more than 5 years old. Information may no longer be current.
Rising HbA1c levels contribute to CV event risk in diabetes, CAD
The longitudinal increase of HbA1c was found to be independently associated with elevated incidence of CV events for patients with diabetes and multivessel CAD, according to findings published in JAMA Network Open.
Researchers found, after adjusting for age, sex, two-vessel or three-vessel CAD, initial CAD treatments, ejection fraction and creatinine and LDL levels, a 1-point increase in the longitudinal value of HbA1c was associated with a 22% higher risk for all-cause mortality, MI and stroke (HR = 1.22; 95% CI, 1.12-1.35).
“This study suggests that the control of glycemia and, consequently, HbA1c should focus not only on achieving strict, isolated levels but also on minimizing variation over time,” Paulo Cury Rezende, MD, PhD, clinical researcher at the Medicine, Angioplasty, or Surgery Research Group and collaborating professor of cardiology at the University of São Paulo Medical School, and colleagues wrote. “Especially in this population with multivessel CAD, in which control of diabetes might influence the occurrence of cardiac events, avoiding variation of HbA1c levels could have the potential to lower cardiovascular risk during a long-term follow-up period.”
Researchers assessed 725 patients who had diabetes, multivessel CAD and complete health records and HbA1c information during a median follow-up of 10 years (median age, 62 years; 64% men), with a mean of number of 9.5 HbA1c measurements per patient.
Researchers observed that the composite endpoint of all-cause mortality, MI or stroke occurred in 36.1% of the cohort during the study period.
“Although all patients underwent rigorous control of HbA1c during follow-up, performed by the same group of physicians using similar treatment strategies, it is possible that the patients with higher fluctuations of glycemia and, consequently, of HbA1c had more severe diabetes, less pancreatic reserve, and, thus, more difficulty controlling glycemia,” the researchers wrote. “Moreover, it is also possible this group of patients had lower adherence to the treatment.” – by Scott Buzby
Disclosures: The authors report no relevant financial disclosures.
Perspective
Back to Top
The basic message is that the higher the A1c, the higher the CV risk. We pretty much know that to be the case from a variety of other population studies of larger size.
The problem with this particular study is ascertainment bias. Rezende and colleagues made a number of adjustments, but they did not adjust for the kind of treatments the patients received vs. the A1c.
People with more mild earlier stages of CVD are more easily treated. Usually there are one or two bypassable lesions in their coronary system. Those can be bypassed, and the patient goes on long-term medical management to prevent any further lesions from developing into acute MI. But people with higher A1c tend to have more pancreatic depletion and a longer disease state. So the result is that when you take people within a treatment group such as CABG, they may tend to have more severe disease. Not always, but they tend to and you need a large population in order to account for that ascertainment bias-based treatment.
Such studies have been done and they all basically support the conclusion to which these authors come, which is that the longer you have diabetes, the more severe the diabetes is, the more likely you are to have significant adverse CV outcomes.
Most individuals are used to thinking of coronary disease in patients with diabetes as arising from large-scale lesions in their major coronary arteries. But what makes diabetes as deadly as it is, is the development of these critical deeper end-organ lesions that are not so bypassable where you cannot get around them. As a result, you get a bunch of people who can only be medically managed. So you want to try and manage those people as early as you can for the development of those distal small-vessel changes. We don't emphasize that enough in our diabetes management programs. We all worry about hitting lipid targets for a big bypassable lesion in the major coronary arteries, but in smaller divisions of the coronary artery, we don't realize that the process is grinding on slowly but surely and it is going to lay waste to this patient if you don't get their peripheral diabetes under control.
Read more about