Progression of diabetic retinopathy after bariatric surgery

To assess the impact of bariatric surgery on the progression of diabetic retinopathy in patients with Type 2 diabetes.

We conducted a retrospective, observational study of patients with Type 2 diabetes who underwent bariatric surgery between 1 January 2001 and 31 December 2012 and had hospital-based retinal screening records. Data were collected from four surgical centres. Those who had pre-operative retinal screening and at least one post-operative retinal screen were eligible for analysis. A generalized linear mixed model was used to explore significant clinical predictors on the post-operative grade severity over time, controlling for important baseline characteristics.

Three hundred and eighteen patients were eligible for analysis. Of these, 68.6% had no diabetic retinopathy pre-operatively compared with 18.9%, 8.5% and 4% with a diabetic retinopathy grade of minimal, mild or moderate and higher, respectively. First post-operative retinal screening results showed that after surgery 73% had no change in their diabetic retinopathy grade, 11% regressed and 16% progressed. The probability of having a diabetic retinopathy grade of moderate or higher over time post surgery was significantly associated with the magnitude of HbA1c reduction from pre-surgery HbA1c levels, a shorter post-operative retinal screening duration, more severe pre-operative retinal screening grade, male gender and non-Maori/Pacific ethnicity.

A higher pre-operative diabetic retinopathy grade, and a large decrease in HbA1c post surgery warrant closer monitoring of diabetic retinopathy after bariatric surgery. Further prospective, randomized studies are required to investigate the gender and ethnic differences found.