Prevalence of type 2 diabetes (T2DM) is increasing sharply. There is a direct relationship between obesity and T2DM. Currently, T2DM has no effective cure. However, there are several diabetes management such as pharmacotherapy, diet and bariatric surgery considered as an effective treatment, and bariatric surgery is considered to be the most effective. There are four types of bariatric surgeries including adjustable gastric banding, biliopancreatic diversion with/without duodenal switch, gastric bypass (GB) and sleeve gastrectomy (SG). GB and SG are the most common bariatric surgery procedures for the treatment of T2DM and obesity. To evaluate the effect of an intervention on the treatment of chronic diseases such as obesity and T2DM, clinical follow-up studies are essential. Biomarkers are currently used in basic and clinical research. Their roles as essential endpoints in clinical trials are accepted universally. In this study two candidate biomarkers, fibroblast growth factor19 (FGF19) and bile acids (BAs) were assumed to play contributory roles in the remission of T2DM after bariatric surgery. Therefore, the main aim of this study was to quantify fasting and postprandial BAs and their computed compositions, and fasting and postprandial FGF19, on the remission of T2DM a year after SG and GB. Also, body composition and diabetes indices were measured a year after SG and GB. SG and GB were compared in this study to investigate which one is superior regarding diabetes alleviation. Due to the very low concentration of BAs in human plasma, liquid chromatography tandem-mass spectrometry (LC-MS/MS) has been used as a reliable method to measure BAs. BAs in this study were measured by using LC-MS/MS method, and FGF19 were quantified by using sandwich ELISA assay. It was found that fasting and postprandial BAs and FGF19 significantly increased a year after either SG or GB. However, fasting and postprandial BAs and FGF19 were not significantly differed between SG and GB. According to the definition of diabetes remission, one-year after SG and GB, the remissions of diabetes were scored. In this study, 38% and 40% of patients who underwent SG and GB, respectively, achieved complete remission of T2DM. A year after bariatric surgery, patients were divided into two groups, remitted and non-remitted. Then, a comparison between the actual values and changes in different BA fractions (fasting and AUC0-60min) and FGF19 (fasting and prandial) were performed to see whether they significantly differed between remitted and non-remitted. Despite the increased level of FGF19 and BAs within the remitted group, they were not significantly different from those of the non-remitted group. Therefore, it is concluded that firstly, both SG and GB are equally effective on the remission of T2DM. Secondly, the increased level of BAs and FGF19 a year after SG and GB play a contributory role for the remission of T2DM, but they are not the main reason for diabetes remission after bariatric surgery.