While Roux-en-Y Gastric Bypass (RYGB)
surgery in obese individuals typically improves glycemic control and prevents
diabetes, it also frequently causes hypoglycemia. Previous work showed attenuated
counter-regulatory responses following RYGB. The underlying mechanisms as well
as the clinical consequences are unclear.
<p>In this study, 11 non-diabetic
subjects with severe obesity were investigated pre- and post-RYGB during
hyperinsulinemic hypoglycemic clamps. Assessments were made of hormones,
cognitive function, cerebral blood flow by arterial spin labeling, brain glucose
metabolism by FDG PET and activation of brain networks by functional MRI. Post-
vs pre-surgery, we found a general increase of cerebral blood flow but a
decrease of total brain FDG uptake during normoglycemia. During hypoglycemia, there
was a marked increase in total brain FDG uptake and this was similar for post-
and pre-surgery, whereas hypothalamic FDG uptake was reduced. During
hypoglycemia, attenuated responses of counterregulatory hormones and
improvements in cognitive function were seen post-surgery. In early
hypoglycemia, there was increased activation post- vs pre-surgery of neural networks
in CNS regions implicated in glucose regulation such as the thalamus and hypothalamus.
The results suggest adaptive
responses of the brain that contribute to lowering of glycemia following RYGB, and
the underlying mechanisms should be further elucidated.</p>
Short‐term ketone monoester supplementation improves cerebral blood flow and cognitive function in adults with obesity: A randomized‐crossover trial
