Physiological effects of mental stress and orthostasis in young insulin-dependent diabetic patients.

The effects of procedures which stimulate sympathetic activity, viz. mental stress induced by a colour-word conflict test (CWT) for 20 min, and orthostasis (ORT) for 8 min were studied in 8 young (16-20 yr) insulin-dependent diabetes mellitus (IDDM) patients and 9 age and sex-matched healthy controls. The IDDM patients showed no signs of neuropathy or retinopathy and their mean HbA1c value was 8.4 +/- 0.6% (normal value less than 5.0%). Blood pressure and heart rate increased significantly during CWT and ORT in both groups. The changes in systolic blood pressure and heart rate were comparable in both groups during CWT; the IDDM group showed a higher (p less than 0.05) heart rate after 8 min of orthostasis, however. CWT and ORT elicited equivalent increases in noradrenaline in venous plasma in both groups (p less than 0.05), but the IDDM patients had 50% lower values (p less than 0.01) at rest, during CWT and at rest after CWT than controls. CWT and ORT evoked equivalent plasma adrenaline increases in both groups. The lipolysis marker, plasma glycerol, was about 40% lower (p less than 0.05) in the IDDM group before and after CWT. Yet, mental stress evoked equivalent increases in glycerol levels (p less than 0.01) in both groups. These findings indicate that sympathetic activity in the young diabetic patients without signs of neuropathy may be blunted.