Gastric bypass surgery reduced the risk for diabetic retinopathy in patients with type 2 diabetes : A nationwide observational study

• Purpose: Diverging results have been reported with regards to the occurrence and progression of diabetic retinopathy following gastric bypass surgery (GBP) in patients with diabetes. We aimed to investigate the incidence of diabetic ocular complications in a nationwide study in Sweden in obese patients with type 2 diabetes mellitus (T2DM) following GBP and compared to a matched cohort of patients with T2DM not subjected to GBP surgery.Setting: Nationwide registry study in Sweden.Methods: We used data from two nationwide registers in Sweden: the Scandinavian Obesity Surgery Registry (SOReg) and the National Diabetes Registry (NDR). Patients with T2DM who had undergone GBP 2007-2013 reported to the SOReg were matched (1:1) with patients with T2DM from the NDR who had not had GBP surgery for obesity, based on sex, age, body mass index (BMI) and calender time (year). Follow-up data were obtained until December 31, 2015. The main outcome was occurrence of new diabetic retinopathy and was assessed with Cox proportional-hazards regression model. The importance of potential risk factors was assessed using a machine learning approach.Results: The study population consisted of 5321 patients who had undergone GBP and 5321 matched controls in NDR, and was followed up for a mean of 4.5 years. Mean age was 49.0 (SD 9.5) in the GBP and 47.1 (11.5) years in the control patients, respectively. BMI and HbA1c at baseline were 42.0 (5.7) and 60.0 (16.8) in the GBP group and 40.9 (7.3) kg/m2 and 58.5 (16.9) mmol/mol in the control group. Duration of diabetes was approximately 6 years in both groups. The risk for new diabetic retinopathy was reduced in the GBP patients (hazard ratio [HR] 0·62, 95% CI 0·49–0·78; p<0.001). The most important risk factors for development of diabetic retinopathy were diabetes duration, HbA1c, glomerular filtration rate (GFR), use of insulin and BMI. There was no evidence of increased risk for development of sight-threatening or treatment-requiring diabetic ocular complications such as diabetic macular edema, proliferative diabetic retinopathy, need for intravitreal drug administration, panretinal photocoagulation or vitrectomy.Conclusions: In this nationwide large cohort study of patients with type 2 diabetes we found a beneficial effect of GBP surgery on the risk for development of diabetic retinopathy. Furthermore, there were no indications for increased occurrence of sight-threatening or treatment-requiring diabetic retinopathy. These data provide support that, besides standard screening for diabetic retinopathy, there is no need for extended ophthalmological surveillance of patients with type 2 diabetes undergoing GBP surgery.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Endokrinologi och diabetes (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Endocrinology and Diabetes (hsv//eng)

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