"Why Is There More Cardiovascular Disease in Diabetes?" Daniel L. Lorber, Practical Diabetology, December 2006.
We like Practical Diabetology because it's straightforward, actionable, and smart — but, be warned, it's for physicians. This article examines how diabetes relates to cardiovascular disease. Cardiovascular disease signifies problems with the heart, veins, or arteries and includes bad events like strokes and heart attacks. Lately, its relationship with diabetes has received broad acknowledgement. The details of the relationship aren't fully clear, but we do know that three quarters of diabetes-related deaths are related to cardiovascular disease. We know that while the incidence of heart disease in the US generally has decreased by 25%, it has increased by 23% in women with diabetes. Not surprisingly, diabetes can impair blood vessels. "The vascular endothelium" refers to the lining of our blood vessels, and Dr. Lorber tells us that, rather than a passive lining, the vascular endothelium is actually like an active organ all by itself. In other words, through hormones and secretions, it actually does something. It actively inhibits clotting, irregular growths, and spasm-like constrictions. A diseased endothelium doesn't just seem not to do these things, but it seems to do the opposite, encouraging clots, spasms, and so on. Though it is sometimes hard to separate the chronic hyperglycemia of diabetes with the other risk factors in type 2 diabetes (like unhealthy lipids or high blood pressure), it appears that hyperglycemia itself actually diminishes the vascular endothelium's ability to do its job. A very large and famous trial in diabetes, the Diabetes Control and Complications Trial (DCCT), showed that early control of hyperglycemia in people with type 1 produced a 42% reduction in cardiovascular events in the long term. Also, there is a five-fold increased risk for cardiovascular disease between ages 20 and 39 in people with type 1 relative to the non-diabetic population. Since people with type 1 don't necessarily have the classic risk factors, both statistics support the idea that hyperglycemia itself is bad for the vascular system. Dr. Lorber also discusses the relationship of hypertension (or high blood pressure), dyslipidemia (more "bad" cholesterol and less "good" cholesterol), and inflammation (a hot research area), with cardiovascular risk. Risk factors seem to be synergistic, meaning the risk of having two is more than the risk of having one plus the risk of having the other. But this article isn't just bad news — it's a call to doctors (and you!) to be vigilant about heart disease, not only by controlling glycemia but also by looking out carefully for other risk factors.
The bottom line: Chronic hyperglycemia seems harmful to blood vessels, which are active organs in preventing heart disease. Not only should glycemia be controlled to reduce the risk of heart disease, but everyone with glucose intolerance (type 1s, type 2s, or pre-diabetics) should be vigilant about the other cardiovascular risk factors like high blood pressure and poor cholesterol levels.