Obesity and
insulin resistance are associated with altered brain
glucose metabolism. Here, we studied brain
glucose metabolism in 22 morbidly obese patients before and 6 months after
bariatric surgery. Seven healthy subjects served as control subjects. Brain
glucose metabolism was measured twice per imaging session: with and without
insulin stimulation (hyperinsulinemic-euglycemic clamp) using [
18F]fluorodeoxyglucose scanning. We found that during fasting, brain
glucose metabolism was not different between groups. However, the hyperinsulinemic clamp increased brain
glucose metabolism in a widespread manner in the obese but not control subjects, and brain
glucose metabolism was significantly higher during clamp in obese than in control subjects. After follow-up, 6 months postoperatively, the increase in
glucose metabolism was no longer observed, and this attenuation was coupled with improved peripheral
insulin sensitivity after
weight loss. We conclude that
obesity is associated with increased
insulin-stimulated
glucose metabolism in the brain and that this abnormality can be reversed by
bariatric surgery.