The effect of insulin-induced hypoglycemia on cerebral glucose metabolism is largely unknown. (13)C MRS is a unique tool to study cerebral glucose metabolism, but the concurrent requirement for [1-(13)C]glucose administration limits its use under hypoglycemic conditions. To facilitate (13)C MRS data analysis we designed separate [1-(13)C]glucose infusion protocols for hyperinsulinemic euglycemic and hypoglycemic clamps in such a way that plasma isotopic enrichment of glucose was stable and comparable under both glycemic conditions. (13)C MR spectra were acquired with optimized (13)C MRS measurement techniques to obtain high quality (13)C MR spectra with these protocols.
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