Bariatric surgery may improve hepatic steatosis in patients with type-2 diabetes. We aimed to compare the effect of Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) on liver fat fraction (LFF), fatty liver index (FLI) and liver enzymes 5 weeks and 1 year after surgery.


Patients with type-2 diabetes and severe obesity were included in the triple blinded randomized Obesity surgery in Tønsberg (Oseberg) trial, and randomly allocated to RYGB or SG. LFF was estimated with the modified Dixon method calculating the percentage of liver-fat using magnetic resonance imaging (MRI). Low grade (G1) hepatic steatosis was defined in patients with values below the 25th percentile of LFF at baseline. Surrogate markers for hepatic steatosis included FLI and liver enzymes alanine aminotransferase (ALAT), gamma-glutamyl transferase (GGT) and alkaline phosphatase (ALP).


Patients who underwent RYGB and SG had a similar short- and medium-term decrease in liver fat fraction, but the RYGB group had a higher serum level of ALAT at 1 year.