Weight-loss surgery might accelerate progression of diabetic retinopathy in some cases, a small pilot study warned.

Seven of the 40 diabetes patients screened about a year before and again after bariatric surgery progressed, for a rate of 17.5 percent, compared with the 2 percent to 4 percent of diabetes patients who develop retinopathy each year, Rebecca Thomas, BSc, of Swansea University in Wales, and colleagues reported here at the American Diabetes Association meeting.

The opposite impact might have been expected, commented Bruce Wolfe, MD, a bariatric surgeon at Oregon Health and Science University in Portland.

"If you have a condition that is the result of the diabetes and the diabetes is in remission, then it makes intuitive sense that the progression of the condition would be arrested," he told MedPage Today.

A few patients did appear to have regression of their eye disease (five moved from minimal to no background diabetic retinopathy), while most remained unchanged after surgery in the study.

Cases that did progress had higher pre-surgical glucose levels and the greatest reduction afterward.

The reduction in fasting glucose after bariatric surgery was 151 mg/dL among those whose retinopathy progressed compared with 49 mg/dL in those who had regression and 29 mg/dL in those with no change in retinopathy.

"A rapid improvement, termed the normoglycemic re-entry phenomenon, may result in the progression of preexisting diabetic retinopathy," Thomas noted at the session, although Wolfe cautioned that any mechanism is speculative at this point.

"Persons with moderate background diabetic retinopathy prior to bariatric surgery should be monitored closely post-surgery for evidence of progression," Thomas suggested.

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