Objective To study the effects of mental stress on the absorption kinetics of insulin and on glucose homeostasis and lipolysis in insulin-dependent diabetes mellitus (IDDM).

Research Design and Methods Nine IDDM patients were exposed to the Stroop color word conflict test (CWT) during 40 min after injection of ¹²⁵I-labeled soluble human insulin (10 U) into the abdomen. Adipose tissue blood flow (¹³³Xe-clearance) was determined concomitantly to elucidate the importance of blood flow for insulin absorption during CWT. The effect of the CWT was followed by measurement of arterial levels of catecholamines and as blood pressure and heart-rate responses. Lipolysis was measured as arterial glycerol levels, and ketone body levels were monitored by determination by β-hydroxybutyrate.

Results Although insulin absorption (residual ¹²⁵I-radioactivity and plasma free insulin levels) and the arterial levels of glucose and β-hydroxybutyrate were not significantly changed by the CWT, arterial glycerol and norepinephrine levels and adipose tissue blood flow were ~ doubled, and epinephrine levels increased fourfold. Heart rate increased ~ 35 beats/min and mean blood pressure ~ 25 mmHg.

Conclusions The results suggest that intense mental stress of 40 min duration does not alter the absorption of subcutaneously injected insulin, glucose homeostasis, or ketone body levels in patients with IDDM, despite a considerable increase in blood flow and lipolysis.