Rebecca Thomas, BSc, of Swansea University in Wales reported that seven of the 40 diabetes patients screened a year before and again after bariatric surgery progressed in the development of retinopathy, for a rate of 17.5%, compared with the 2% to 4% of diabetes patients who develop retinopathy each year, and colleagues reported here at the American Diabetes Association meeting.
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.
Although glucose levels can normalize after bariatric surgery for obese diabetes patients, those patients still need eye screening, agreed Philip R. Schauer, MD, director of the Bariatric and Metabolic Institute at the Cleveland Clinic, citing his group's STAMPEDE trial results last year in the New England Journal of Medicine.
His trial prospectively collected retinal photographs and should be able to answer how bariatric surgery impacts the diabetic eye compared with those who get intensive medical management instead.
The weight loss after surgery (a mean of 32 kg, or 70 lbs) was accompanied by improved glycemic control. Mean hemoglobin A1c went from 7.9% to 6.4%, and the average fasting glucose fell from 189 to 126 mg/dL.
Overall, 65% of the individuals had no evidence of diabetic retinopathy to start with. Four of these 26 patients (20%) developed one or two microaneurysms after surgery that moved them into the category of mild background diabetic retinopathy.
Of the 23% who had mild background diabetic retinopathy before surgery, most stayed in that category or regressed after the procedure.
The researchers suggested patients fell into two strata: low risk of progression and some evidence of regression among those with minimal or no preexisting diabetic retinopathy when getting bariatric surgery versus greater risk among those with moderate background diabetic retinopathy or worse.
- Weight-loss surgery might accelerate progression of diabetic retinopathy in some cases.
- Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
- Note that cases that did progress had higher pre-surgical glucose levels and the greatest reduction afterward.
Thomas RL, et al "Does diabetic retinopathy progress following bariatric surgery in persons with type 2 diabetes?" ADA 2013; Abstract 155-OR.