Does insulin species modify counterregulatory hormone response to hypoglycemia?

Objective: To examine whether pork and human insulin induce different counterregulatory responses to hypoglycemia. Research Design and Methods: The responses to a mild hypoglycemic stimulus were determined in 35 healthy young adults with the glucoseclamp technique to ensure standardization of glucose and insulin levels. Either pork (n = 15) or human (n = 20) regular insulin was infused (0.8 mU · kg^-1 · min^-1) to lower plasma glucose from 4.7 ± 0.07 to 3.3 ± 0.04 mM (both groups) over ∼40 min. Plasma glucose was maintained at that level (with variable rate glucose infusion) for an additional 60 min. Results: Steady-state insulin levels were similar in both groups (316 ± 50 vs. 280 ± 29 pM, pork vs. human). Before insulin administration, basal counterregulatory hormone levels were indistinguishable. Most importantly, after plasma glucose was lowered, hormonal responses were nearly identical. No significant differences in peak values of epinephrine (1769 ± 404 vs. 1775 ± 311 pM, pork vs. human), norepinephrine (1.64 ± 0.23 vs. 1.87 ± 0.20 nM, pork vs. human), glucagon (163 ± 29 vs. 175 ± 20 ng/L, pork vs. human), growth hormone (14 ± 3 vs. 17 ± 3μg/L, pork vs. human), or cortisol (543 ± 83 vs. 458 ± 28 nM, pork vs. human) occurred. Conclusions: Our data suggest that pork and human insulin produce a comparable and robust hormonal response in healthy adults under conditions of controlled hypoglycemia.