Type 2 diabetes and cardiovascular disease (CVD) have been closely linked in several respects, but little solid quantification of the risk diabetes poses to cardiovascular mortality has been achieved. A recent study has made a profound discovery, that in the long-term, mortality due to cardiovascular events (heart attacks and strokes), is equally likely for diabetics with no previous cardiovascular disease history, as it is for individuals with known cardiovascular disease (and non-diabetic). The study was conducted solely on males, but the results are suspected to extend to both sexes.
The connections between cardiovascular disease and diabetes are numerous. From one angle is the largely supported notion that diabetics are at higher risk for developing cardiovascular disease. Cardiovascular disease refers to all diseases associated with one’s arteries or veins, but arterial disease (atherosclerosis) is the most common cardiovascular disease. Atherosclerosis can range from causing a minor cardiovascular event, such as a minor heart-attack, to life-threatening strokes and heart-attacks, but is also treatable if caught in relatively early stages, which unfortunately is rarely the case (diagnosis of atherosclerosis often comes following a cardiovascular event).
A separate but equally important link between diabetes and cardiovascular disease is their mutual connection to the rising obesity epidemic. In this case, it’s more of a race to see which disease develops first. Obese individuals are at tremendously increased risk for both diabetes and cardiovascular disease, so an obese cardiovascular patient might very well also develop diabetes, and vice versa.
Past research has indicated that having diabetes contributes to the risk of dying from a cardiovascular event, but the conclusions have been far from definitive as to how much diabetes really contributes to the fatal cardiovascular event. The authors of the current study say that in some past research, “coronary or cardiovascular mortality among people with type 2 diabetes without previous cardiovascular disease was equivalent to that of people without diabetes who had had a first myocardial infarction or first cardiovascular event. Thus, there is controversy as to whether diabetes alone confers a risk of cardiovascular mortality similar to that associated with having had a first coronary or cardiovascular event.”
This statement is also the foundation for the current study, which aimed to see if diabetics with no cardiovascular disease history did indeed have an inherent risk of dying from a cardiovascular event. “The rationale for undertaking the present study was the need for more information about the cardiovascular prognosis of men with type 2 diabetes relative to men with cardiovascular disease,” states the study.
The researchers had two primary goals and expectations for their study, both of which were met. The researchers wanted to prove that a diagnosis of diabetes might not immediately trigger cardiovascular disease, and a subsequent fatal cardiovascular event, but would indeed often have this effect in the long run, on a similar level to cardiovascular disease patients.
“We formulated 2 hypotheses: first, that within the first few years after diagnosis, the risk of a fatal cardiovascular event would be higher among men with a first cardiovascular event and no diabetes than among men with type 2 diabetes and no cardiovascular disease; and second, that over the longer term, the risk of death within these 2 clinical subsets would tend toward equivalence,” says lead author Dr. Gilles Dagenais and his co-author’s.
To confirm their speculations, the research team analyzed three groups of patients. The initial study population consisted of 4,376 men between 35 and 64 years of age, who in the year 1974 did not have cardiovascular disease. The men were tracked for the following 24 years, in which they were separated into the three groups. Group one consisted of men with diabetes and no cardiovascular disease (137 men), group two of non-diabetics with cardiovascular disease (being identified as having a “first cardiovascular event,” such as a myocardial infarction or stroke), which accounted for 527 men, and those with both diabetes and cardiovascular disease (18 men).
There was also of course a control group, consisting of “normal” men with no diabetes or cardiovascular disease (627 men). The numbers above do not add up to 4,376, which is due to the elimination throughout the 24 years of the study, of individuals who acquired certain interfering attributes (such as smoking, or other related diseases), or who died of other causes or too early to take significant enough measurements (it’s noted that 1,112 men died between 1974 and 1985, and were subsequently eliminated from the final analysis).
The results were mostly as expected. In the long-term, which meant following five years after diagnosis, diabetics had a 23.4% likelihood of dying from a cardiovascular event. Similarly, 24.5% of patients with cardiovascular disease and no diabetes died of cardiovascular events. This was in comparison with only 6.9% of the controls (no diabetes or cardiovascular disease), dying from cardiovascular events, demonstrating that both diabetes and cardiovascular disease, by themselves, represent a three to four-fold increase in risk of cardiovascular induced mortality.
Interestingly, it’s noted that “total mortality,” which means death from any cause, was essentially equivalent between the diabetic and cardiovascular disease groups. In addition, 38.9% of those men with both diabetes and cardiovascular disease, died of cardiovascular events, re-enforcing the dangers of these diseases.
Before the five year marker of post-diagnosis for diabetics, which put the diabetics at similar risk for cardiovascular events as cardiovascular disease patients, the risk of a cardiovascular death was not nearly as great. In fact, within the first five years of diabetic diagnosis, those with previous cardiovascular disease history were approximately twice as likely to die from a cardiovascular event than the newly diagnosed diabetics. This observation is most obviously due to the fact that diabetes is a progressive condition, meaning its effects get worse with time. As was seen above, following the five years, the differences in cardiovascular mortality risk was minimal between the two groups.
The primary importance of this study is its concrete support of the belief that diabetes significantly increases the risk of fatal cardiovascular events. While previously speculated, past research had numerous discrepancies and limitations. This research clearly demonstrates that having diabetes not only increases the risk of cardiovascular disease and cardiovascular death, but increases it to such a level that it is as likely for a diabetic to die from a cardiovascular event as it is for someone with cardiovascular disease!
Type 2 diabetes is a disease of epic proportions, effecting more than 24 million adults in the United States, and hundreds of millions more world wide. Aso, in the U. S. there are more than 57 million people at risk for type 2 diabetes. Cardiovascular events are known to be the leading cause of death throughout the world, but especially so in the United States (accounting for approximately 35% of deaths). The above demonstrated connection between type 2 diabetes and cardiovascular mortality, along with rising numbers of diabetics, spells big trouble for the future.
Fortunately, type 2 diabetes is often preventable, as well as manageable, with proper exercise and nutrition and regular medical checkups. Awareness and initiative taken against diabetes is the only hope for stemming the tide of rising diabetes incidence, and of course subsequent diabetes induced cardiovascular mortality.
Source: Defeat Diabetes Foundation: Dagenais, Gilles. St.-Pierre, Annie. Bogaty, Peter. et al. Canadian Medical Association Journal. “Comparison of prognosis for men with type 2 diabetes mellitus and men with cardiovascular disease.” January 2009.