Acute hypoglycemia impairs the functioning of the central but not peripheral nervous system

Acute hypoglycemia impairs functions of the central nervous system, but few controlled studies have assessed the impact of hypoglycemia on the functio n of the peripheral nervous system. Sixteen non-diabetic humans underwent t wo separate hyperinsulinemic glucose clamp procedures on different study da ys, in a counter-balanced fashion. On one occasion, euglycemia was maintain ed (blood glucose, 5.0 mmol 1(-1)), and on the other occasion, hypoglycemia (blood glucose, 2.6 mmol 1(-1)) was induced. During each condition, subjec ts performed a combined psychometric, cognitive-experimental and psychophys ical test battery, and measures were made tin the dominant median and commo n peroneal nerves) of the motor nerve conduction velocities and the amplitu des of the motor action potentials. Hypoglycemia caused impaired performanc e of general cognitive and information processing tasks (P<.05), but nerve conduction velocities and the amplitudes of motor action potentials were un affected. Conduction velocities of the common peroneal nerve decreased from baseline within each experimental condition, perhaps due to hyperinsulinem ia. Overall, these results demonstrate that multiple levels of information processing in the brain may alter while peripheral nerve function remains i ntact, and imply that peripheral neurons do not have the same obligate requ irement for glucose as a metabolic fuel as neurons of the central nervous s ystem. (C) 2001 Elsevier Science Inc. All rights reserved.