Postprandial Profiles of Metabolites and Appetite-regulating Hormones in Plasma and Cerebrospinal Fluid

Inclusion Criteria: * 10 male patients with obesity (BMI \>30) and type 2 diabetes * 10 male volunteers with normal weight (BMI 20-24) matched by age * 10 male volunteers with obesity (BMI \>30) matched by age Exclusion Criteria: 1. Unwillingness to participate or wish to withdraw from ongoing protocol 2. Hepatic disease or hemorrhagic diatheses (including abnormal International Normalized Ratio (INR), bilirubin, blood levels of thrombocytes, alanine-aminotransferase (ALAT)) 3. Anticoagulant treatment (e.g. treatment with warfarin, apixaban or another oral anticoagulant) 4. Anaemia (p-hemoglobin below normal range) 5. Nephropathy (se-creatinine \>130 μM and/or albuminuria) 6. Suspected difficult access to the spinal canal (e.g. pronounced scoliosis, spinal stenosis, osteoporotic coincidence in the lower back, spina bifida, meningocele after surgical intervention) 7. Lumbar skin infection (e.g. herpes zoster, pustules or ulcers) 8. Medical history with headaches - both in connection with dura puncture and frequent headaches of other types 9. Central nervous system disease (including dementia, previous stroke, multiple sclerosis, epilepsy, etc.) 10. Clinical suspicion of increased intracranial pressure (headaches, visual disturbances etc.) 11. Patients with type 2 diabetes: Treatment with DPP-4 inhibitor or GLP-1 receptor agonist. Late diabetic complications including proliferative diabetic retinopathy (anamnestic), arteriosclerotic cardiovascular disease (heart failure or previous ischemic event/myocardial infarction)