No Change in Retinopathy in Diabetes 2 Years After Surgery

Marlene Busko

July 01, 2014

Two years after bariatric surgery for patients with type 2 diabetes, there has been no change in diabetic retinopathy, results from the STAMPEDE trial indicate. Therefore, regular eye exams are still important, the investigators stress.

"I wasn't sure what gastric bypass would do to diabetic retinopathy," lead author Rishi P. Singh, MD, staff physician at the Cole Eye Institute, in Cleveland Clinic, Ohio, told Medscape Medical News. "I was pleasantly reassured by the fact that they didn't have a higher incidence of retinopathy or significant progression of the disease."

Dr. Singh reported 2-year ophthalmology findings from STAMPEDE at the recent American Diabetes Association (ADA) 2014 Scientific Sessions.

"This is the first time that a prospective, randomized clinical trial has shown that intensive medical management vs gastric bypass doesn't appear to increase the retinopathy incidence or progression, nor does it increase the rate of vision loss or changes in intraocular blood pressure (a sign of glaucoma)," he commented.

"The take-away point is that…ophthalmic management of our [diabetic] patients through yearly evaluations which is what the ADA and [American Academy of Ophthalmology] AAO recommend should still continue," he cautioned.

"Despite the fact that these patients had essentially normal HbA1c values [at] year 2 in the gastric-bypass group, that doesn't mean that they were free of retinopathy, so it's important to follow those patients long term and monitor them for eye complications."

Asked to comment, bariatric surgeon Bruce M. Wolfe, MD, at Oregon Health and Science University, Portland, said it will take many more years to begin to see any impact upon retinopathy. "The induction of remission or improvement in diabetes control is positive for the patient, but drawing conclusions about the many-year process of diabetic complications of diabetic neuropathy or diabetic retinopathy is premature."

Patients who are informed that their diabetes has gone into remission after they have had bariatric surgery may think, "I don't need to go to these eye assessments anymore," he added, but that would be too hasty, he stressed.

Diabetes is likely to recur in some patients — possibly in 5, 10, or 20 years — and those patients are at increased risk for microvascular complications. "I agree with the authors that it is important for diabetic patients to continue to have regular eye examinations," which can spot any changes and lead to earlier treatment to delay disease progression, he told Medscape Medical News.

Unknown Impact of Bariatric Surgery on Retinopathy

After patients with type 2 diabetes have bariatric surgery, their glycemic control improves.

However, it is not yet known how these rapid changes in HbA1c affect the progression of microvascular complications such as retinopathy. There have been some reports of improvements, but other studies have reported worsening of these outcomes, as was seen in the DCCT trial or in a small series of patients presented at last year's ADA meeting, Dr. Singh explained.

STAMPEDE randomized 150 obese patients with uncontrolled type 2 diabetes to intensive medical therapy alone (50 patients), Roux-en-Y gastric-bypass surgery (50) or sleeve gastrectomy (50). To be eligible, patients had to be 20 to 60 years old and have an HbA1c greater than 7% and a body mass index (BMI) of 27 to 43 kg/m2.

Intensive medical therapy consisted of antidiabetic therapeutic agents plus diet and lifestyle counseling and regular follow-up, with a target HbA1c of 6% or lower. Patients had had diabetes for about 8.5 years, and more than half were taking 3 or more antidiabetic medications.

As reported by Medscape Medical News [4], the 3-year nonophthalmic primary and secondary outcomes were recently presented at the American College of Cardiology meeting and simultaneously published. Mean HbA1c dropped by 1.1% from 9.0% at baseline in those who got medical therapy, by 2.8% from 9.3% in the gastric-bypass group, and by 2.7% from 9.5% in the sleeve-gastrectomy patients.

The trial was also designed to measure ophthalmic outcomes at baseline and at 2 years and 5 years, as secondary outcomes.

About 80% of the patients had no evidence of retinopathy at baseline. From baseline to 2 years, there was no significant change in retinopathy scores for patients who had no retinopathy or mild to severe nonproliferative retinopathy or proliferative retinopathy, for patients who had received each of the 3 treatments.

The mean baseline and 2-year visual acuity scores were logMAR 0 (20/20) for each of the 3 treatment groups.

Retinopathy Evolves Slowly, Need Frequent Eye Exams

Dr. Singh said that in all honesty, longer-term follow-up will be needed to properly gauge the effect of bariatric surgery on diabetic retinopathy.

Progressing from mild to severe diabetic retinopathy is "typically a process that would potentially occur anywhere from 10 to 15 years [out], but it can be shorter depending on how bad sugar control really is," he explained.

"If HbA1c is, for example, 11%, 12%, or 13%, those patients can progress twice as fast as those with HbA1c of 6% or 7%. It [also] depends on the length of time a patient has diabetes."

The 5-year data from STAMPEDE should shed more light on this microvascular outcome, he concluded.

Dr. Singh receives consulting fees from Alcon Laboratories, Genentech, Regeneron, ThromboGenics, and Valeant Pharmaceuticals and is on the speakers' bureau for Genentech, Regeneron, and ThromboGenics.

American Diabetes Association 2014 Scientific Sessions; June 16, 2013. Abstract 356-05.

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