The metabolic and liver-related outcomes of bariatric surgery in adult patients with insulin-treated type 2 diabetes and nonalcoholic fatty liver disease at high risk of liver fibrosis

Abstract

Background: Nonalcoholic fatty liver disease (NAFLD) has become the most common cause of chronic liver disease, with a prevalence estimated to between 20% and 30% of the general population and approximately 70% of stage 2 obese people with type 2 diabetes (T2D) with normal liver enzymes. Objectives: To investigate the metabolic and liver-related outcomes of bariatric surgery among patients with insulin-treated T2D and NAFLD who are at high risk of liver fibrosis. Setting: More than 600 locations within the United Kingdom. Methods: The study comprises a retrospective cohort comparison of patients with NAFLD and a fibrosis 4 (Fib-4) score > 1.45 who received a bariatric intervention versus comparable patients who received no bariatric intervention. Metabolic outcomes (glycated hemoglobin [HbA1C] level, weight, body mass index [BMI], and Fib-4 score) and composite liver-related outcomes (cirrhosis, portal hypertension, liver failure, and hepatoma) were compared between groups over a period of 5 years. The outcomes were adjusted for baseline and time-varying covariates. Results: The study sample included 4108 patients, 45 of whom underwent bariatric surgery. The mean age at baseline was 62.4 ± 12.4 years; 43.8% of patients were female; the mean weight was 89.5 ± 20.8 kg; the mean BMI was 31.7 ± 7.6 kg/m2; and the mean HbA1C level was 68.4 ± 16.7 mmol/mol. In addition, the median Fib-4 score was 2.3 (interquartile range, 1.7–4.2). During the 5 years during which follow-up outcomes were recorded, the weight and BMI reductions were significantly lowered compared with baseline in the bariatric surgery group. Similarly, the HbA1C levels were lower in the bariatric surgery group, with statistically significant differences observed in the first and second postintervention years (bariatric surgery versus non–bariatric surgery patient levels at 1 year, 63.1 mmol/mol versus 68.1 mmol/mol, respectively [P = .042], and at 2 years, 62.7 mmol/mol versus 68.1 mmol/mol, respectively [P = .028]). No significant difference was observed between groups in the proportion of patients with liver fibrosis or the likelihood of developing composite liver disease during the follow-up period (bariatric surgery group, 8.9%; non–bariatric surgery group, 4.7%; X2 = 1.75; P = .18). Conclusion: Bariatric surgery amongst patients with insulin-treated T2D with NAFLD who were at high risk of liver fibrosis was associated with significant improvements in metabolic outcomes. No significant adverse effects were observed with regards to liver-related outcomes.