Abstract
BACKGROUND: Alanine aminotransferase (ALT) is used to detect non-alcoholic fatty liver disease and has been associated with increased risk of metabolic syndrome and type II diabetes mellitus (T2DM). Bariatric procedures result in significant weight loss and a rapid resolution of T2DM. We aimed to study the impact of bariatric interventions on ALT levels in patients with or without T2DM and compare this effect between different types of weight-loss procedures. METHODS: We reviewed 756 patients undergoing bariatric surgery. Demographics, co-morbidities, baseline and post-operative ALT and HbA1C levels, weight-loss data, and diabetes status were recorded. ALT levels were compared between different procedures and between diabetic and non-diabetic patients. Chi-square test, ANOVA, and t test were used to evaluate outcomes. RESULTS: Males and diabetics had significantly higher ALT at baseline. Both Roux-en-Y gastric bypass surgery (RYGB) and laparoscopic adjustable gastric banding (LAGB) resulted in significant reduction in ALT levels beginning at the third post-operative month (20 and 17 %, respectively, compared to baseline, p < 0.001). ALT remained at the new low level up to year 3 after surgery. The degree of reduction was similar for both procedures and was independent of the degree of weight loss. In diabetics, ALT reduction was associated with improvement in disease; but in T2DM patients who remained on insulin, ALT remained elevated. CONCLUSIONS: RYGB and LAGB decrease ALT levels to the same degree and independent of weight loss. Our data confirm higher ALT in diabetics and demonstrate a rapid normalization after bariatric surgery with a simultaneous decrease in HbA1C. These results suggest that ALT may be used as a marker of metabolic improvement after bariatric surgery.