Gut Hormones and Roux en Y Gastric Bypass

Inclusion criteria

• Aged 18 - 70 years.
• Male or female.
• Eligible for bariatric surgery under the NHS.
• Diagnosed with impaired glucose regulation or type 2 diabetes, according to WHO 2011 criteria.
• Those with diabetes should be stable and well controlled with either diet or one oral hypoglycaemic agent.
• HbA1c ≤9.0% or 74.9 mmol/mol.

Exclusion criteria

• History of any medical, psychological or other condition, or use of any medications, including over-the-counter products, which, in the opinion of the investigators, would either interfere with the study or potentially cause harm to the volunteer.
• Without access at home to a telephone or other factor likely to interfere with ability to participate reliably in the study.
• Pregnancy or breastfeeding.
• Smokers.
• Unable to maintain adequate contraception for the duration of the study and for one month afterwards.
• History of hypersensitivity to any of the components of the subcutaneous infusions.
• Donated blood during the preceding 3 months or intention to do so before the end of the study.
• Insulin treatment.
• Uncontrolled hypertension.
• Any other co-morbidity that would compromise the validity of the study or the safety of the participant such as heart failure, clinically apparent cardiovascular disease.
• Volunteers on anti-coagulants such as warfarin and factor Xa inhibitors will not undergo adipose tissue biopsy.
• Unable to give informed consent.
• Previous bariatric surgery.
• Unable to undergo fMRI due to:
• Claustrophobia.
• Pacemaker, metal implant, clips, implanted device, shrapnel or bullet, metal in eyes that precludes magnetic resonance imaging.
• Significant structural abnormality on magnetic resonance brain scan