Abstract
It was investigated whether the deficient insulin response in maturity-onset diabetics
is determined by monoaminemediated mechanisms.
The material comprised 11 maturity-onset diabetics and 10 non-diabetics as a control
group, all non-obese. The tests were carried out on 2 consecutive days, by IV GTT
on the first day and IV GTT combined with IV infusion of the α-receptor blocker phentolamine
(Regitine®) 0.5 mg/min on the second day. Serum glucose and serum insulin concentrations were
determined.
In the non-diabetic group no increase in serum insulin was found on phentolamine infusion
alone, whereas the insulin response after IV injection of glucose was potentiated
by phentolamine. In the diabetic group, on the other hand, a statistically significant
increase (p < 0.001) in serum insulin was found when phentolamine was given without
glucose. During an IV GTT the diabetic group showed a slight and delayed insulin response
as usual. This response was potentiated, but not normalized, by phentolamine.
It is concluded that a monoamine-mediated mechanism may play a role in the sluggish
insulin release after glucose tolerance tests in maturity-onset diabetics.
Key words
c-3'5' AMP - Phentolamine (Regitine®) - Maturity-Onset Diabetes - Serum Insulin Level - IV GTT - Monoamine-Mediated Mechanism
