Longitudinal Phenotyping of Bariatric Surgery Patients

This study aims to assess how the gut microbiome affects the host phenotype following bariatric surgery through altered gut microbiome-host co-metabolism. The secondary objective is to identify novel biomarkers for the preoperative prognostication of T2DM remission following bariatric surgery.

The study will longitudinally phenotype obese diabetics and non-diabetics undergoing Roux-en-Y Gastric Bypass or Sleeve Gastrectomy surgery. Patients will be assessed preoperatively and at 3 months and 1 year postoperatively. Clinical measures recorded will include; 1) anthropometric & physiological measurements, 2) demographic details, 3) biochemical parameters including HbA1c, 4) anti-hyperglycaemic and other medication use, 5) co-morbidity status and 6) dietary choices through 24hr dietary recall questionnaires.

Blood, urine and stool samples will be collected at the above time points. Changes to the microbiome will be assessed using metagenomic sequencing. Global metabonomic profiles of serum, urine and faecal water will be generated using 1H-NMR. Further targeted analyses of bile acid and short-chain fatty acid profiles will be performed using LC-MS / GC-MS.

The study will utilise multivariate statistical analysis techniques to identify metabolic pathways altered following intervention, and novel host-microbiome co-metabolism pathways that impact upon phenotype. A supervised multivariate analysis, mapping T2DM outcomes to metagenomic and metabonomic data will be performed with the aim of identifying novel preoperative biomarkers that are able to prognosticate T2DM resolution following bariatric surgery.

Inclusion criteria

• Obese (BMI>30kg/m2)
• Type 2 Diabetes Mellitus and non-diabetic
• Failure of efforts at lifestyle modification and dieting
• Fitness for anaesthesia and procedure
• Willingness to comply with the trial protocol

Exclusion criteria

• Previous bariatric surgery
• Pregnancy or intention to become pregnant during trial period
• Lack of capacity to consent
• Previous major abdominal surgery (Small or large bowel resection, stomach, liver, pancreatic or splenic surgery. Does not include patients who have previously had an appendicectomy, cholecystectomy or hernia repair).