The Link Between Diabetic Retinopathy & Cardiovascular Disease
Risk factors increase as vision problems persist
By A.Paul Chous, MA, OD, FAAO
Diabetic retinopathy occurs when the tiny capillaries within our light-sensitive retinas become damaged and balloon outward (these are called microaneurysms). Over time, these fragile blood vessels may begin to leak blood and fluid. This early stage of retinal damage does not typically affect vision, and is known as non-proliferative retinopathy. As the condition progresses, fluid swelling may compromise vision (diabetic macular edema) and abnormal, new blood vessels may grow, bleed, and produce fibrovascular scar tissue that detaches the retina (proliferative retinopathy), leading to blindness without prompt treatment.
Diabetic retinopathy is still the leading cause of new blindness in working age Americans. For those of us with diabetes, our risk of vision loss is about 20 times higher than for those without diabetes. Fortunately, we also know that most cases of blindness can be prevented with tight control of blood glucose levels and blood pressure; regular dilated eye exams by an optometrist or ophthalmologist experienced with diabetes; and timely treatment when indicated. What many of us may not realize, however, is that the mere presence of diabetic retinopathy actually increases our cardiovascular disease risk, which includes stroke and heart attack.
A 2005 study investigating the relationship between retinopathy and type 1 diabetes in Europe showed a two-fold increased risk of cardiovascular disease (CVD) for patients with proliferative retinopathy over an eight-year period. A 2007 study of patients with type 2 diabetes in Finland showed a 2- to 4-fold increased risk of CVD over 18 years in patients with proliferative retinopathy. In addition, this same study showed that even non-proliferative diabetic retinopathy increased the risk of CVD by 30-70%, with higher risk in women. Most recently, a 2009 study appearing in the American Journal of Cardiology showed that for patients with type 2 diabetes, non-proliferative retinopathy increased cardiovascular disease risk 70% over a 7-year period, whereas proliferative retinopathy doubled the risk over the same time frame. Of utmost importance, these increased risks occurred despite taking other cardiovascular risk factors (e.g. smoking, high blood pressure, poorly controlled blood sugar, family history) into account.
What does all this mean?
1 - It appears that diabetic retinopathy, in and of itself, is a risk factor for cardiovascular disease. This is not all that surprising, since diabetes affects blood vessels throughout the body. What the eye doctor sees inside your eyes is directly related to your overall health, especially your vascular health.
2 - More severe retinopathy (proliferative versus non-proliferative) appears to increase cardiovascular disease risk, all other factors being equal. This means that we should do everything possible to keep pre-existing retinopathy from getting worse.
3 - Many physicians have incorrectly assumed that mild retinopathy is not that important because it doesn't affect eyesight. The reality is that any diabetic retinopathy is significant because its presence increases the odds of having or developing cardiovascular diseases like heart attack and stroke, as well as the risk of dying from these conditions. Patients who develop even mild retinopathy should be considered for preventive care above and beyond that offered to patients with diabetes but without retinopathy (e.g. tighter blood glucose, blood pressure and blood lipid control, additional diabetes education, more frequent follow-up and assessment of cardiovascular health, etc.)
My advice is to be aware of cardiovascular disease risk factors, such as retinopathy. Make sure your diabetes physician, your eye doctor, and you are all aware of your retinal status and the studies cited here.
For more information on diabetic eye disease, consult Dr. Chous' book Diabetic Eye Disease: Lessons From a Diabetic Eye Doctor, Fairwood Press, Seattle, 2003.
Read more about Dr. Chous here.
Visit Dr. Chous' website here.
NOTE: The information is not intended to be a replacement or substitute for consultation with a qualified medical professional or for professional medical advice related to diabetes or another medical condition. Please contact your physician or medical professional with any questions and concerns about your medical condition.
1 - Diabetic retinopathy is associated with mortality and cardiovascular disease incidence: the EURODIAB prospective complications study. Diabetes Care. 2005 Jun;28(6):1383-9.
2 - Retinopathy predicts cardiovascular mortality in type 2 diabetic men and women. Diabetes Care. 2007 Feb;30(2):292-9.
3 - Ability of retinopathy to predict cardiovascular disease in patients with type 2 diabetes mellitus. Am J Cardiol. 2009 May 15;103(10):1364-7.
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