Impact of sweet drink on pituitary response and subject comfort during insulin tolerance test

Abstract

The insulin tolerance test (ITT) is the gold standard for the diagnosis of cortisol and growth hormone (GH) deficiencies. Once hypoglycemia is detected whether patients should receive carbohydrates to recover faster from hypoglycemia is controversial. The aim of our study was to assess the impact of shortening the duration of hypoglycemia by providing a sugar drink on patient comfort and hormonal responses. This prospective, single-center, crossover, single-blind study enrolled 15 healthy participants. Each subject performed two ITT: one with normal Cola and the other with Cola Zero. Glucose and hormone levels were measured at baseline and after the induction of insulin-induced hypoglycemia. Patient tolerance to ITT was evaluated using reported hypoglycemia side effects, visual analog scale scores, and quality-of-life questionnaire. Normal Cola shortened the period of hypoglycemia (plasma glucose < 40 mg/dl) from 30 to 15 min (p = 0.005), allowing a higher proportion of participants to recover from potentially dangerous values after 45 min (12 vs. 5; p = 0.008). Cola also improved patient comfort, as evaluated using a visual analog scale (VAS score 2.6 vs 3.7, p = 0.016). Sugar did not significantly change the median cortisol and GH peaks. Body mass index was the only factor determining the cortisol peak, independent of the injected insulin dose. The time to reach hormone peaks was similar between the two protocols. Cortisol and GH values were significantly higher at 120 min in the Cola Zero group, suggesting the prolongation of hypothalamic-pituitary stress in the absence of sugar. Our study confirmed that rapid correction of hypoglycemia during ITT improves subject comfort, reduces the duration of hypoglycemia and associated symptoms, while guaranteeing unchanged cortisol and GH peaks.