Undergoing Gastric Bypass Could Reduce Risk of Diabetic Retinopathy in Obese Diabetics

A matched cohort study of more than 10k patients suggests undergoing gastric bypass surgery was associated with a 38% reduction in risk of developing diabetic retinopathy among obese patients with diabetes.

While previous research has described cardiovascular risk reductions associated with undergoing bariatric surgery, new research suggests it could also help prevent one of the most debilitating complications of diabetes.

An analysis of 2 national databases in Sweden, results of the study indicate undergoing gastric bypass surgery in patients with obesity and diabetes led to a 38% reduction in risk of developing diabetic retinopathy.

“In this large nationwide matched cohort study of patients with diabetes, gastric bypass was associated with a decreased risk of developing new diabetic retinopathy,” wrote investigators. “Furthermore, there were no indications of increased occurrence of sight-threatening or treatment requiring diabetic retinopathy in patients with no diabetic retinopathy at baseline.”

With the obesity epidemic expected to grow and bariatric surgeries growing in popularity, investigators from Sweden sought to define how undergoing gastric bypass surgery might influence the development of diabetic ocular complications later in life. Investigators designed their analysis to explore this subject using data from the Scandinavian Obesity Surgery Registry and the National Diabetes Register.

From the Scandinavian Obesity Surgery Registry, investigators identified 5321 patients with diabetes who had undergone gastric bypass surgery between January 1, 2007 and December 31, 2013. These patients were then matched based on sex, age, BMI, and year with 5321 patients with diabetes from the National Diabetes Register.

The group who had undergone gastric bypass had a mean age of 49.0 (SD, 9.5) years, mean diabetes duration of 6.8 (SD, 6.3) years, and contained 3223 women. The group of matched controls had a mean age of 47.1 (SD, 11.5) years, mean diabetes duration of 6.4 (SD, 6.4) years, and contained 3395 women. The mean follow-up time for the entire study population was 4.5 (SD, 1.6) years. The mean BMI and HbA1c concentrations at baseline were 42 (SD, 5.7) and 7.6% (SD, 1.5), respectively, among patients in the surgery group. In the control group, mean BMI and HbA1c concentrations at baseline were 40.9 (SD, 7.3) and 7.5% (SD, 1.5), respectively.

The primary outcomes of the analysis were the incidence of new diabetic retinopathy and other diabetic ocular complications. The investigators’ statistical analysis was performed from October 5, 2018 to September 30, 2019.

Initial analysis indicated significant differences in change from baseline BMI and HbA1c concentration one year after gastric bypass surgery when comparing the study arms. When assessing for diabetic retinopathy, investigators identified incident diabetic retinopathy among 188 patients in the surgery group and 317 patients in the control group.

Further analysis suggested undergoing gastric bypass surgery was associated with a 38% reduction in risk for new diabetic retinopathy in this patient population (HR, 0.62; 95% CI, 0.49-0.78; P <.001). Investigators noted their analyses indicated diabetes duration, HbA1c concentration, use of insulin, glomerular filtration rate, and BMI were the most important risk factors for development of diabetic retinopathy.

“These data support the view that, besides standard screening for diabetic retinopathy, there is no need for extended ophthalmologic surveillance of patients with diabetes undergoing gastric bypass surgery if there is no diabetic retinopathy at baseline,” added investigators.

This study, “Association of Gastric Bypass Surgery With Risk of Developing Diabetic Retinopathy Among Patients With Obesity and Type 2 Diabetes in Sweden,” was published in JAMA Ophthalmology.