Endocrine Abstracts

Background and aim: Insulin tolerance test (ITT) is the gold standard for the diagnosis of cortisol and growth hormone deficiencies in adults. Once hypoglycaemia (<40 mg/dl) is achieved, some medical centers give sugar to their patients (food, drink or glucose infusion), others do not and let the blood glucose rise spontaneously. Although critical hypoglycaemia results in discomfort and potential complications for the patients there is so far no recommendation on the subject. The aim of our study was to compare the stress response induced by insulin hypoglycaemia in healthy subjects, depending on whether or not they received a sugar-sweetened beverage on time of hypoglycaemia.

Method: We conducted a prospective, single-center study that recruited 10 healthy subjects (5 women and 5 men; mean age of 28.5 years ( 6.67 S.D.). Each subject performed two ITT: during one they received 150 ml of regular Coca-Cola and during the other they received 150 ml of diet Coca-Cola (zero) after hypoglycaemia was achieved. In addition to usual hormone measurements we performed glucose continuous monitoring analysis and salivary cortisol and cortisone dosages.

Results: Regular cola significantly shortened the time spent in severe hypoglycaemia (<40 mg/dl) (10 min vs 25 min; P=0.03). The median duration of side effects tended also to be shortened (45' versus 100'; P=0.47) and the subjects discomfort was significantly reduced as evaluated by a visual analog scale (VAS score 2 vs 3.4; P=0.04). Although the median peak concentration of plasma cortisol was significantly higher in the absence of sugar-sweetened beverage (579 vs 526 nmol/l), we didn’t observe any significant difference in terms of plasma cortisol increment, median peak concentration of salivary cortisol and cortisone, and of serum GH and ACTH. Moreover all subjects demonstrated adequate stimulated cortisol and GH levels (cortisol >374 nmol/l with a minimum of 390 nmol/l; and GH>3 µg/l). The best correlation between plasma cortisol and salivary cortisol as well as cortisone levels was obtained at time 120’ (salivary cortisol r = 0.90, salivary cortisone r=0.92; P<0.001).

Conclusion: Our study suggests that glucose intake after achieving hypoglycaemia during ITT decreases the duration of severe hypoglycaemia and improves patient’s comfort while ensuring adequate pituitary response according to the most recent thresholds proposed in the literature. Our results also confirmed the necessity to revise the stimulated plasma cortisol thresholds downwards, and the interest and validity of salivary cortisol and cortisone measurements.