Lipid Levels, Statin Use Not Linked to Retinopathy Incidence in Type 1 Diabetes

By Will Boggs MD

NEW YORK (Reuters Health) - Neither lipid levels nor statin use appears to affect the incidence of proliferative diabetic retinopathy and macular edema, according to a new study.

Earlier studies have suggested a possible association between serum lipids and diabetic retinopathy and macular edema, but the associations lost significance after adjustment for other variables.

For their study, online December 11 in JAMA Ophthalmology, Dr. Barbara E. K. Klein from University of Wisconsin School of Medicine and Public Health in Madison and colleagues used data from the Wisconsin Epidemiologic Study of Diabetic Retinopathy (WESDR).

Among 903 individuals with younger-onset type 1 diabetes the estimated prevalence of proliferative diabetic retinopathy (PDR) was 41.0% per person-visit and 23.8% for macular edema. The estimated incidence was 1.21% per person-year for PDR and 0.77% per person-year for macular edema, the researchers say.

Higher serum total cholesterol was associated with a modestly increased prevalence of PDR and macular edema, but not with an increased incidence of the conditions, and the link disappeared after adjustment for hemoglobin A1c levels.

Although higher HDL cholesterol levels were associated with a decreased prevalence of PDR and macular edema after adjustment, they were not associated with the incidence of PDR or macular edema. The same was true of statin use.

Neither total cholesterol nor HDL cholesterol was associated with mortality.

"The lack of an observed association of lipids and the incidence of these severe retinal outcomes was compatible with the possibility that these serum lipids are not important in the etiologic classification of PDR and macular edema," the researchers conclude.

Dr. Viswanathan Mohan from Madras Diabetes Research Foundation and Dr. Mohan's Diabetes Specialties Centre in Chennai, India, recently reviewed the association between serum lipids and diabetic retinopathy.

"(I)n the literature, as the authors themselves allude to, earlier cross-sectional studies as well as our own, an association between serum cholesterol and LDL cholesterol and maculopathy has been shown in patients with diabetes," he told Reuters Health by email. "However, this is the first longitudinal follow-up study to look at the association between serum lipids and diabetic retinopathy."

"Interestingly in this study also the authors show an association between serum lipids and prevalent retinopathy, but in their follow-up studies they could not find such an association with new-onset retinopathy," Dr. Mohan said. "As cross-sectional studies cannot be related to causality, whereas longitudinal studies can, it is possible that the earlier associations noted in cross-sectional studies between serum lipids and diabetic retinopathy (specifically maculopathy) could be due to the effect of some confounding factors."

"While this may not directly affect the treatment of type 1 diabetes, it does not detract from the need to assess dyslipidemia, and when present, treat the same," Dr. Mohan concluded. "Even if serum lipids are not causative for microvascular complications like retinopathy, controlling dyslipidemia would still be important for the prevention for the macrovascular complications of diabetes."

Dr. Klein did not respond to a request for comments.

SOURCE: https://bit.ly/1w2nJfl

JAMA Ophthalmol 2014.

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