Connections Between Retinopathy and Cardiovascular Disease in Patients With Type 1 Diabetes

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Diabetic retinopathy is associated with mortality and cardiovascular disease incidence: the EURODIAB Prospective Complications Study, by M.V. van Hecke and colleagues. Diabetes Care 28:1383-1389, 2005.

Research has shown that people with type 2 diabetes and retinopathy (a disease of the blood vessels in the eye) are more likely to have cardiovascular disease (heart and blood vessel disease) and to die at an earlier age. This may be because diabetic eye disease and heart and blood vessel disease share the same "risk factors" -- people who have these diseases are also likely to have high blood glucose, high blood pressure, high cholesterol (a waxy fat-like substance that builds up in the blood vessels), and high triglycerides (types of fat that build up in the blood vessels).

There's little information, though, on the relationship between diabetic eye disease and heart and blood vessel disease in people with type 1 diabetes, and in general the link between diabetic eye disease and heart and blood vessel disease is not clear. It's possible that causes other than high blood glucose, high blood pressure, high cholesterol, and high triglycerides may trigger diabetic eye disease and heart and blood vessel problems.

Why did the researchers do this particular study?

The researchers wanted to learn more about the relationship between diabetic eye disease, heart and blood vessel disease, and early death in patients with type 1 diabetes. They also wanted to learn more about how high blood glucose, high blood pressure, high cholesterol, and high triglycerides affect the relationship between heart and blood vessel disease and eye disease.

Who was studied?

The researchers studied 2,237 type 1 diabetic patients from 16 European countries. The patients were between 15 and 60 years old.

How was the study done?

Special photographs were taken of the patients' eyes. Researchers looked at the photographs and assigned each patient to a certain level of eye disease, ranging from 1 to 6. Researchers checked the patients 6-8 years later and reviewed the medical records of the patients who had died. The researchers measured the blood pressure, cholesterol, triglycerides, weight and height, as well as protein levels in the urine of the patients who were still living.

What did the researchers find?

Researchers found that early death from all causes was much higher in patients with diabetic eye disease than in those without eye disease. It was highest in patients with the most severe form of diabetic eye disease. When researchers factored out the problems that make patients more likely to have heart and blood vessel disease, patients with the most severe diabetic eye disease still had a higher risk. However, patients with mild or moderate eye problems did not have a higher risk.

What were the limitations of the study?

There were several limitations of this study. First, when researchers later checked the patients, 45% had lost their photographs or had missing data. Second, it was difficult to find data on how patients died because of strict privacy laws in several countries. Third, the measurements were only done once, and there may have been mistakes or mix-ups that affected the results.

What are the implications of the study?

Patients with type 1 diabetes and eye disease have a higher risk of getting heart and blood vessel disease and dying at an earlier age. In most cases, high blood glucose, high blood pressure, high cholesterol, and high triglycerides are the causes of both diseases. But in the most severe cases of diabetic eye disease, there may be other causes that trigger both diseases.

Read more about the ADA's recommendations on treating patients with diabetic retinopathy.

FOR MORE INFORMATION

Diabetes and Retinopathy

The Uncomplicated Guide to Diabetes Complications, 2nd ed., by Marvin E. Levin and Michael A. Pfeifer (Alexandria, Va., ADA, 2002).

High cardiovascular disease mortality in subjects with visual impairment caused by diabetic retinopathy, by U. Rajala and colleagues. Diabetes Care 23: 957-961, 2000.