Investigation of the cerebral responses to hunger, satiety and food ingestion in people with obesity-related insulin resistance and Type 2 diabetes. A neuroimaging study using an obesity surgery (Roux-en-Y Gastric Bypass) model

Recruitment & Eligibility

Status: Completed

Sex: All

Target Recruitment: 48

Inclusion Criteria

1. Aged 18 years or over
2. Able to provide informed consent to participate in the study
3. Able to lie flat in the scanner for duration of scans
4. Right handedness (because of the possibility of lateralisation of cerebral responses)
5. For women of childbearing potential in all groups:
5.1. Using effective form of contraception
5.2. Willing to have a pregnancy test at the start of each scanning visit
5.3. Willing to attend for scanning visits during the first 10 days of their menstrual cycle
6. For STUDY ONE (RYGB):
6.1. Roux-en-Y gastric bypass 3 months to 10 years previously
6.2. BMI 25 - 40 kg/m^2
6.3. Weight loss of more than 10% of excess body weight since surgery
7. For STUDY TWO, Group A (non-overweight, no obesity surgery group):
7.1. No previous obesity surgery
7.2. BMI 20 - 25 kg/m^2
8. For STUDY TWO, Group B (overweight/obese, no obesity surgery with insulin resistance with or without Type 2 diabetes):
8.1. No previous obesity surgery
8.2. BMI 25 - 40 kg/m^2
8.3. HOMA2-IR greater than or equal to 1.47 with or without Type 2 diabetes (managed with diet/exercise/metformin only)
9. For STUDY TWO, Group C (overweight/obese, no obesity surgery, insulin-sensitive group):
9.1. No previous obesity surgery
9.2. BMI 25 - 40 kg/m^2
9.3. HOMA2-IR greater than or equal to 0.76

Exclusion Criteria

1. Inability to give formal consent
2. Unable to communicate in spoken English (due to the importance of being able to communicate while study subjects are in the scanner)
3. Age less than 18 years
4. Pregnancy, planning pregnancy, or breastfeeding
5. Currently enrolled in other clinical study
6. Left-handedness
7. Taking any glucose-lowering medications (except metformin). Subjects taking metformin will be asked to omit it the day before the Test Meal/OGTT visit and the PET scanning visits because metformin affects gastric emptying and thus may affect nutrient absorption).
8. Advanced retinopathy
9. Any significant brain disorder, e.g. previous significant head injury, epilepsy, cerebrovascular disease
10. Use of psychotropic medication, e.g. antidepressants, antipsychotics
11. Unstable angina, myocardial infarction in the previous year, uncontrolled congestive cardiac failure
12. Chronic kidney disease (Stage 3 - 5)
13. Liver function tests more than three times the upper normal limit
14. Coagulopathy (international normalised ratio [INR] greater than 1.5 or platelets less than 50 x 10^9/L)
15. Anaemia (Hb less than 10 g/dL)
16. Recent history of cancer (less than 5 years)
17. Contraindication to magnetic resonance imaging, e.g. cardiac pacemaker