Inhibition by salbutamol of GHRH-induced GH release in type 1 diabetes mellitus.

Patients with type 1 diabetes mellitus (IDDM) show augmented GH secretion, which is implicated in the pathogenesis of microvascular complications. On the other hand, it is well known that beta-adrenergic receptors have inhibitory influence on GH secretion, likely via stimulation of hypothalamic somatostatin. Since the possibility of pharmacological suppression of GH secretion would be of value in IDDM, we investigated the effect of salbutamol (SAL, 4 mg orally at -60 min) on the GH response to GHRH (1 micrograms/kg iv at 0 min) in 6 well-controlled (mean HbA1c +/- SEM: 7.3 +/- 0.5%) patients with IDDM. Salbutamol was able to inhibit basal GH levels (p < 0.05) as well as to abolish the GHRH-induced GH rise. After SAL administration, a significant (p < 0.05) reduction of glucagon levels was also found. Our data show that the enhancement of beta 2 adrenergic activity by oral therapeutical doses of SAL inhibits basal and GHRH-stimulated GH secretion in patients with IDDM.