Differential association of serum lipids with diabetic retinopathy and diabetic macular edema

To assess the association of serum lipids with diabetic retinopathy (DR), diabetic macular edema (DME), and macular thickness in adults with diabetes.

Diabetic patients aged ≥ 18 years were prospectively recruited from specialized eye clinics in Melbourne, Australia. Fasting total-C (cholesterol), triglyceride, HDL-C, non-HDL-C, and LDL-C were assessed. DR was graded from fundus photographs and classified into mild, moderate, severe nonproliferative, and proliferative DR and separately graded for the presence of DME, including clinically significant macular edema (CSME). Macular thickness was assessed using optical coherence tomography (OCT).

A total of 500 participants (median age, 65 years) were examined. DR, DME, and CSME were present in 321 (66.2%), 149 (33.0%), and 68 (15.0%) patients, respectively. Serum lipid levels were not related to DR or DME. In multivariate models adjusted for traditional risk factors and lipid medications, persons with higher total-, LDL-, and non-HDL-C were more likely to have CSME (odds ratio of 1.54, 1.49, and 1.63 per 1-SD increase, respectively; all P < 0.05). No association was found for serum lipids with macular thickness, as assessed by OCT. The pattern of these associations remained similar in both type 1 and type 2 diabetes, although it was statistically significant only in type 2 diabetes.

Serum lipids are independently associated with the CSME, but not with DR, mild or moderate DME, or macular thickness. These data reflect the different impact of hyperlipidemia in the pathogenesis of DR and DME and may explain the discrepancies in previous studies.