Hypoglycemia Following Insulin and Proinsulin. A Comparison

Summary

The counterregulatory hormonal response to proinsulininduced hypoglycemia was investigated in eight volunteers. Proinsulin cleared slower from the circulation than insulin. Hypoglycemia occurred slower (2P < 0.005) and was prolonged, while the overall hypoglycemic activities were comparable. The antilipolytic effect of proinsulin was also prolonged (2P < 0.001). The response of epinephrine to hypoglycemia was less pronounced after proinsulin (2P < 0.05). The amount of epinephrine was correlated to the rate of fall in plasma glucose (P < 0.005). The production of lactate induced by β-stimulation was also correlated to the fall of glucose (P < 0.005). The responses of prolactin (2P < 0.02), norepinephrine (2P < 0.02), cortisol, and growth hormone were attenuated following proinsulin. The decreases of serum potassium and serum phosphate (2P < 0.05) were less pronounced. Symptoms like sweating (2P < 0.01) and dizziness (2P < 0.01) were milder after proinsulin.

It is concluded that the rate of fall in glucose concentration determines the differing counterregulatory responses. We don't relate the differing counterregulatory responses to special insulin-like properties of proinsulin, but to the slower kinetics which is emphasized by the intravenous bolus injection.

Key-Words

Proinsulin - Hypoglycemia - Counterregulation - Epinephrine - Lactate - Phosphate - Trigger Mechanism