Introduction: Long-term effects of gastric bypass (GBP) surgery have been presented in observational and randomized studies, but there is still only limited data for obese persons with type 2 diabetes (T2DM), in particular regarding postoperative complications. We investigated postoperative outcomes after GBP in a nation-wide cohort.

Research Design and Methods: In this observational study, we merged data from the Scandinavian Obesity Surgery Registry, the National Diabetes Register and national databases. We matched persons with type 2 diabetes who had undergone GBP with persons not surgically treated for obesity, based on sex, age, BMI and propensity score. The risks of postoperative outcomes were assessed using Cox regression model adjusted for sex, age, BMI and socioeconomic status.

Results: 5321 T2DM patients who had undergone GBP and 5321 control persons were followed for up to 9 years. We confirm lower risks of all-cause mortality (49%) and cardiovascular disease (34%), found positive effects on severe kidney disease, but also demonstrate significantly increased risks (2 to 9-fold) of several short-term complications after GBP. There were higher rates of abdominal pain and gastrointestinal conditions frequently requiring additional surgical procedures, apart from reconstructive plastic surgery. Long-term, the risk of anemia was 92% higher, malnutrition appeared approximately 3-fold more often, while psychiatric diagnoses were 33% increased, and alcohol abuse was 3-fold higher than in the control group.

Conclusions: This nation-wide study confirms the benefits but also describes the panorama of adverse events after bariatric surgery in obese persons with T2DM. In order to maximize the benefit and minimize the risk of unfavorable results after bariatric surgery, a thorough and long-term follow-up and support of these patients seems paramount. Better selection of patients for such treatment could probably also improve results.


V. Liakopoulos: None. A. Svensson: None. I. Naslund: Other Relationship; Self; Baricol Bariatrics AB, Sweden. B. Eliasson: Advisory Panel; Self; Amgen Inc.. Speaker's Bureau; Self; AstraZeneca. Advisory Panel; Self; Boehringer Ingelheim GmbH. Speaker's Bureau; Self; Eli Lilly and Company. Advisory Panel; Self; Merck Sharp & Dohme Corp.. Speaker's Bureau; Self; Novo Nordisk A/S. Consultant; Self; Sanofi.

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