Diabetes experts agree losing weight is beneficial for diabetes patients, but questions remain about how weight loss affects the chances of developing some of the side effects of diabetes, such as retinopathy (damage to the blood vessels at the back of they eye). Recently, two studies have reported valuable new information on the subject.
In the first study, which was done by researchers in Sweden and published in the medical journal JAMA Ophthalmology, it was determined that patients who underwent gastric bypass surgery showed a reduced risk of developing diabetic retinopathy (DR) compared to those who didn’t have the surgery. (Gastric bypass surgery is a procedure that shrinks the volume of the stomach, causing patients eat less and lose weight). The researchers studied data from two national registers in Sweden — the Scandinavian Obesity Surgery Registry and the National Diabetes Registry. They identified 5,321 people with diabetes who had undergone weight-loss surgery and compared them to an equal number of people with diabetes who had not had the surgery. The groups were similar in how long they had diabetes, in the male/female ratio, and in their blood pressure, blood sugar levels and kidney function, although the surgery patients were a bit older (by about two years) and had a slightly higher BMI (body-mass index, an indication of obesity). The patients were followed up for about four-and-a-half years.
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During that time, 188 patients in the weight-loss surgery group developed DR. In the control group, however, the number who developed retinopathy was 317.
Risk factors for retinopathy
The researchers identified certain risk factors in those who developed retinopathy. Among them were how long the patients had diabetes, their blood sugar levels, whether or not they used insulin, and their BMI. In all, the results were a clear indication of the benefit of weight-loss surgery. The researchers did, however, issue one caution about their findings. Some accounts, they pointed out, have indicated that patients who already have retinopathy before surgery might later have problems. As they put it, “There are reports describing sight-threatening postoperative deterioration in DR, suggesting that closer monitoring of these patients is desirable. Regression of DR has been described after bariatric surgery but not confirmed.”
But just a week later, however, a study from researchers in Canada reported details on preexisting DR and weight-loss surgery. For the study, which was published in the American Journal of Ophthalmology, the researchers looked for published reports that had investigated comparisons between DR in people with type 2 diabetes who underwent weight-loss surgery and in people with type 2 diabetes who hadn’t. They identified 14 such studies involving more than 110,000 surgery patients and 253,000 non-surgery patients. The average age of the subjects was about 43 and three out of four were women.
Like the researchers in Sweden, the authors of the new report found weight-loss surgery to be highly beneficial. According to Yung Lee, MD, of McMaster University in Hamilton, Ontario, “bariatric surgery lowered the risk of all DR by 83% and sight-threatening DR by 53% compared to medical management.” However, the authors also discovered that the Swedish researchers were right to suspect that patients who already have DR when they undergo weight-loss surgery could experience vision deterioration after the operation. It turned out that early worsening of DR was more serious in the patients who already had DR before surgery. As Dr. Lee expressed it, “We were surprised to find that early worsening of diabetic retinopathy occurs, in particular for patients with existing proliferative disease.”
The benefits of weight-loss surgery remain indisputable, but the new report indicates that diabetes patients who have the surgery will need to be monitored for eye problems. According to Dr. Lee, “These findings suggest a need for early vigilant eye exams for patients who undergo bariatric surgery, especially if they already have sight-threatening retinopathy.”
Want to learn more about keeping your eyes healthy with diabetes? Read “Diabetic Eye Exams: What to Know,” “Eating for Better Vision and Healthy Eyes,” and “Keeping Your Eyes Healthy” and watch “Diabetes and Your Eyes.”
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