Preserved counterregulatory hormone release and symptoms after short term hypoglycemic episodes in normal men

To test the hypothesis that subsequent neuroendocrine and symptomatic responses are sustained after short term hypoglycemic episodes of less than 1-h duration, we studied hypoglycemia on 4 consecutive days and after an 8-day pause in 10 nondiabetic men. Highly reproducible decreases in plasma glucose (< 2.8 mmol/L) occurred on study days 1, 2, 3, 4, and 12 after iv insulin boluses (0.04 U/kg). Levels of the counterregulatory hormones rose during the hypoglycemic episodes in all instances, but maximal concentrations on study day 4 were not attenuated: glucagon (peaks on day 1 vs. day 4), 150 +/- 10 vs. 180 +/- 20 ng/L; cortisol, 400 +/- 30 vs. 420 +/- 40 nmol/L; ACTH, 12 +/- 2 vs. 13 +/- 2 pmol/L; GH, 11.1 +/- 1.8 vs. 12.5 +/- 2.2 micrograms/L; norepinephrine, 1.68 +/- 0.17 vs. 1.65 +/- 0.13 nmol/L; and epinephrine, 1370 +/- 440 vs. 1520 +/- 480 pmol. On each study day, symptoms of hypoglycemia were produced after induction of hypoglycemia, and there was no decrease in the degree of symptomatology on subsequent days. The multivariate analysis of variance showed no day to day differences in plasma glucose, counterregulatory hormones, or hypoglycemic symptoms. We conclude, firstly, that after short term hypoglycemic episodes, the neuroendocrine and symptomatic responses remain completely intact in normal individuals and, secondly, that short term periods of hypoglycemia are fundamentally different from prolonged periods, as described previously.