Weight loss after bariatric surgery reverses insulin-induced increases in brain glucose metabolism of the morbidly obese

  1. Pirjo Nuutila1,4
  1. 1Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland
  2. 2Department of Radiology, University of Turku and Turku University Hospital, Turku, Finland
  3. 3Department of surgery, University of Turku and Turku University Hospital, Turku, Finland
  4. 4Department of Medicine, Turku University Hospital, Turku, Finland
  5. 5Department of Biomedical Engineering and Computational Science, School of Science, Aalto University, Espoo, Finland
  6. 6Brain Research Unit, O.V. Lounasmaa Laboratory, School of Science, Aalto University, Espoo, Finland
  1. Corresponding author: Pirjo Nuutila, pirjo.nuutila{at}utu.fi

Abstract

Obesity and insulin resistance are associated with altered brain glucose metabolism. Here, we studied brain glucose metabolism in twenty-two morbidly obese patients before and six months after bariatric surgery. Seven healthy subjects served as controls. Brain glucose metabolism was measured twice per imaging session: with and without insulin stimulation (hyperinsulinemic euglycemic clamp) using [18F]FDG scanning. We found that during fasting, brain glucose metabolism was not different between groups. However, the hyperinsulinemic clamp increased brain glucose metabolism in a wide-spread manner in the obese but not in controls, 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.

  • Received October 22, 2012.
  • Accepted March 10, 2013.

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