Study procedures
hypoglycemia
HYPOGLYCEMIA, BLOOD, NOCTURNAL HYPOGLYCEMIA
Participants installed a glucose sensor (Dexcom G4 or G5 Platinum, Dexcom, USA) 24–48 h before study visits and installation training was offered for those unfamiliar with the technology. At least 6-day intervals separated study visits. The day before each study visit, participants had to refrain from exercise and alcohol consumption and reduced their nighttime basal insulin by 10% to minimize nocturnal hypoglycemia risks. Upon arrival to the testing centre, Dexcom data were uploaded and verified. A test was reported in the case of nocturnal hypoglycemia (two separate periods of 20 min or one single period exceeding 40 min with glucose levels < 3.5 mmol/L). At 7:30 a.m., participants had subcutaneous rapid insulin analog injection according to body weight and starting glucose level to induce hypoglycemia. Insulin doses were 0.13 U/kg for plasma glucose (PG) 10.0–15.0 mmol/L, 0.10 U/kg for PG 7.0–9.9 mmol/L, and 0.08 U/kg for PG 4.0–6.9 mmol/L. Intravenous catheters were installed to collect venous blood samples every 15 min for PG above 5 mmol/L, every 10 min for PG above 4 mmol/L, and then every 5 min until hypoglycemia threshold. Then, ® glucose tablets for 16 g or 32 g were consumed and PG-T0 was defined as time 0 post-initial CHO consumption. Blood samples were later collected at 5, 10, 15, 20, 30, 45, and 60 min. Participants consumed a second treatment with 16 g of CHO at 15 min if PG-T15 was < 3.0 mmol/L and at 45 min if PG-T45 was < 4.0 mmol/L.All blood samples were centrifuged immediately, and PG was measured using YSI 2300 STAT Plus analyzer (Yellow Springs, OH, USA). Plasma samples were stored at −80°C until subsequent measurement of insulin and glucagon using respective immunological assays (Millipore, Billerica, MA, USA).