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No to mild retinopathy found in many patients with long duration of diabetes
A study assessed retinopathy in patients who had diabetes for 50 years or more.
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CHICAGO — Patients with a long duration of diabetes but without microvascular complications may have certain genetic and biochemical factors that protect them from developing these complications, according to new study data.
Investigators at the Joslin Diabetes Center in Boston investigated diabetic retinopathy in 247 patients whose mean duration of diabetes was 56 years.
“Diabetic retinopathy is a common microvascular complication of diabetes and is the leading cause of blindness in the working-age population,” said Jennifer K. Sun, MD, an investigator in the section on eye research and an ophthalmologist at Beetham Eye Institute at Joslin.
Given the long duration of the disease, nearly all patients were expected to have developed some level of diabetic retinopathy. Previous estimates suggested that up to 60% would have developed proliferative diabetic retinopathy. To the surprise of the investigators, however, a high number of patients, more than 40%, exhibited no to mild nonproliferative diabetic retinopathy, according to Dr. Sun. These data were presented at the American Diabetes Association 67th Annual Scientific Sessions.
Surprising findings
Dr. Sun and colleagues examined ocular characteristics in diabetic patients, including diabetic retinopathy level, central retinal thickness and visual acuity. Patients underwent fundus photographs; optical coherence tomography; measurement of height, weight, HbA1c, lipid and C-peptide levels; and genotyping of HDL DQB1, DQA1 and DRB1.
The investigators said 44% of patients had no to mild nonproliferative diabetic retinopathy. Specifically, 6.9% of patients had no discernible diabetic retinopathy, 1.5% had questionable diabetic retinopathy, 34.3% had mild nonproliferative diabetic retinopathy, 8.3% had moderate nonproliferative diabetic retinopathy, 0.5% had severe nonproliferative diabetic retinopathy and 48.6% had proliferative diabetic retinopathy. More severe retinopathy was significantly correlated with the presence of microalbuminuria (P = .002).
More than half of the patients (56%) had visual acuity of 20/20 or better, 96.2% had visual acuity of 20/40 or better, and 1.6% had 20/200 vision or worse, according to Dr. Sun. Also, retinal thickness increased with more advanced retinopathy, increasing age and male gender.
Classic risk factors
“In this unique cohort of patients … retinopathy severity level did not correlate with many of the classic risk factors associated with more advanced eye disease,” Dr. Sun said. The classic risk factors include duration of diabetes, age at onset, current glycemic control and age.
The association between microalbuminuria and retinopathy status was highly significant. It was not surprising that patients with more severe retinopathy were more likely to have microalbuminuria, as renal disease and eye disease often coexist in diabetic patients, Dr. Sun said.
It is unknown whether patients with no to mild disease previously progressed to more severe levels of diabetic retinopathy and then regressed or have never progressed past mild retinopathy, she said.
“These findings in our diabetic patients with extreme duration of diabetes suggest that protective factors may exist against microvascular complications that differ from those that have been previously identified in patients with shorter disease duration,” Dr. Sun said. “Our hope is that further analysis of findings from these patients may yield early markers of disease and/or molecular targets for prevention of diabetes and its complications.”
This article also appeared in Endocrine Today, a SLACK Incorporated publication.
For more information:
- Sun JK, Keenan HA, et al. Risk factors predictive of retinopathy severity, retinal thickness and visual acuity in patients with 50 years or more of type 1 diabetes mellitus. Presented at: American Diabetes Association 67th Scientific Sessions; June 22-26, 2007; Chicago.