In the largest study to examine the relationship between clinically major macular edema and blood cholesterol levels, Harvard researchers found that aggressive treatment to reduce high cholesterol levels in patients with type 1 diabetes may protect their vision and cardiovascular health. For the study, the researchers evaluated data from the Diabetes Control and Complications Trial. The trial included 1441 participants who were followed for an average of 6.5 years and had their cholesterol levels checked annually.
The results of the study showed that individuals with the highest levels of low-density lipoprotein (LDL; "bad") cholesterol had 2 times the risk of developing macular edema, or fluid in the macula of the eye, compared with those with the lowest LDL levels. The participants with the highest ratio of total cholesterol to high-density lipoprotein (HDL; "good") cholesterol had a 4-fold increased risk of the vision problem.
The researchers concluded that high cholesterol, particularly the total-to-HDL cholesterol ratio, is a risk factor for clinically significant macular edema. The findings, reported in Diabetes (November 2004), may also add support to current treatment guidelines that suggest aggressive lowering of high cholesterol in patients with diabetes.