Effects of bariatric surgery on kidney diseases, cardiovascular diseases, mortality and severe hypoglycaemia among patients with Type 2 diabetes mellitus

Abstract

Abstract Background Bariatric surgery has been widely indicated for the management of obesity and related comorbidities. However, there are uncertainties pertaining to the risks of post-bariatric severe hypoglycaemia (SH), cardiovascular diseases (CVDs), end-stage kidney diseases (ESKDs) and all-cause mortality in obese patients with Type 2 diabetes mellitus (T2DM), especially among Asian populations. Methods A retrospective population-based cohort of 1702 obese T2DM patients who were free of CVD and ESKD were assembled based on the 2006–17 Hospital Authority database. One-to-five propensity-score matching was used to balance baseline covariates between patients in bariatric surgery and control groups. Incidence rates (IRs) of SH, CVD, Stage 4/5 chronic kidney diseases (CKD), ESKD and all-cause mortality events for two groups were calculated. Hazard ratios (HR) for SH, CVD and Stage 4/5 CKD events were assessed using Cox-proportional hazard models. Changes in estimated glomerular filtration rate (eGFR) and urine albumin–creatinine ratio (UACR) were measured up to 60 months. Results Over a mean follow-up period of 32 months with 5725 person-years, cumulative incidences of mortality, CVD, Stage 4/5 CKD, ESKD and SH were 0, 0.036, 0.050, 0.017 and 0.020, respectively. The surgery group had a significant reduction in risk of CVD events (HR = 0.464, P = 0.015) and no occurrence of mortality events. However, there were no significant differences in risks of SH [HR = 0.469, 95% confidence interval (CI): 0.204–1.081], Stage 4/5 CKD (HR =0.896, 95% CI: 0.519–1.545) and ESKD (HR = 0.666, 95% CI: 0.264–1.683) between two groups, although IRs were lower in the surgery group. Surgical patients had significantly higher eGFR within 12 months and had significantly lower UACR until 48 months. Conclusions Among obese T2DM patients, bariatric surgery lowered the risk of CVD and mortality, and was beneficial towards the kidney outcomes.