Plasma epinephrine and norepinephrine response to stimuli in autonomic neuropathy of type 2 diabetes mellitus

The objective of this study was to examine epinephrine and norepinephrine p lasma levels in patients with clinical type 2 diabetes mellitus, at differe nt stages of autonomic neuropathy. Eighteen patients were classified in gro ups without (n = 6) and with early (n = 6), definite (n = 3) and severe (n = 3) neuropathy. Blood catecholamine levels were measured after the Valsalv a maneuver, cold exposure and orthostatic tests. The norepinephrine basal l evels were lower in patients with severe neuropathy (0.4 +/- 0.2 nmol/l), c ompared with the group with no neuropathy (1.3 +/- 0.5 nm/l, p = 0.034), or with early neuropathy (1.3 +/- 0.7 nm/l, p = 0.035). After the Valsalva ma neuver, no increase was found in the group with severe alteration In patien ts without neuropathy, cold exposure induced a peak of norepinephrine at 5 min (Delta = 1.9 +/- 1.6 nmol/l). The increase was lower in groups with def inite and severe damage. In patients with definite or moderate neuropathy, the orthostatic test induced minimal or no response. The epinephrine respon se to the maneuvers was not significant, and no differences were found amon g the groups. Norepinephrine basal levels and cold responses are diminished in patients with definite and severe autonomic neuropathy. This provides f urther evidence on their impaired response to stress. The comparable epinep hrine levels in patients with or without autonomic neuropathy indicates tha t adrenal medullar function is not significantly altered.