High Blood Lipids Linked to Macular Edema in Type 1 Diabetes

Aggressive lowering of blood lipids in patients with type 1 diabetes could protect their vision as well as their cardiovascular health.

Researchers from Harvard Medical School, found that individuals with the highest serum LDL had double the risk of developing clinically significant macular edema (CSME) compared to those with the lowest LDL levels. Those with the highest total-to-HDL cholesterol ratio had a fourfold increased risk of CSME.

Dr. Debra A. Schaumberg of Brigham and Women’s Hospital and colleagues noted that, CSME is the leading cause of vision loss in diabetic patients, , and while high blood glucose has been tied to the development and progression of retinopathy, the relationship between blood glucose control and CSME is not as clear.

"A relationship of lipids with CSME and hard exudate is biologically plausible because elevated lipid levels are associated with endothelial dysfunction, which appears to play an important role in the pathogenesis of DR, particularly in relation to breakdown of blood-retinal barrier," the researchers note. "Moreover, elevated levels of LDL and triglycerides in type 1 diabetes have been linked with higher levels of fluorescent advanced glycation end products, which are hypothesized to play an important role in the pathogenesis of diabetes complications."

Dr. Schaumberg and her colleagues analyzed data from the Diabetes Control and Complications Trial, which included 1,441 patients with diabetes followed for an average of 6.5 years. Study participants’ blood lipids were checked annually.

Their study, , is the largest prospective investigation to date of CSME and serum lipids which, is published in the November issue of Diabetes

Patients in the top quintile of total-to-HDL cholesterol ratio had 3.84 times the risk of CSME of those in the lowest quintile, while those with the highest LDL were 1.95 more times likely to develop CSME. The researchers found that those in the highest total-to-HDL cholesterol ratio and LDL groups were twice as likely to develop hard exudate, while those in the highest quintile for triglycerides had triple the risk.

Adjustment for HbA1C attenuated the relationship between serum lipid levels and CSME, although this relationship remained significant. However, no relationship was seen between lipid levels and the progression of diabetic retinopathy or development of proliferative diabetic retinopathy.

"These prospective data indicate that elevated serum lipids, particularly total-to-HDL cholesterol ratio and triglycerides, are independent risk factors for both CSME and hard exudate," Dr. Schaumberg and her colleagues write. "If indicative of a causal relationship, these data lend additional support to current treatment guidelines recommending aggressive lowering of elevated lipids among diabetic patients."

Diabetes 2004;53:2882-2892.