Insulin administration and rate of glucose appearance in people with type 1 diabetes

Abstract

Objective To assess whether prandial insulin, additional to basal insulin, has an effect on the rate of glucose appearance from a meal in people with type 1 diabetes.

Research Design and Methods The rate of glucose appearance from a mixed meal (R_{a meal}) was investigated in six adult (age 24±2 yrs; mean±SD), lean (BMI 23.6±1.5 kgm^-2) subjects with well controlled type 1 diabetes (duration 7.9±6.9 yrs, HbA1C 7.6±0.9%) with/without prandial insulin. Actrapid was infused to maintain euglycaemia before meals were consumed. Subjects consumed two identical meals on separate occasions and R_{a meal} was measured using a dual isotope method. [6,6-²H₂]glucose was incorporated into the meal (0.081 g/kg body weight) and a primed, constant/variable rate, infusion of [1,2,3,4,5,6,6-²H₂]glucose was administered. In the tests with prandial insulin, an additional bolus dose of Actrapid was given 20 min before the meal at 0.1U/kg body weight.

Results Insulin concentration with prandial insulin was significantly higher than during basal insulin studies (119±16 vs 66±15 ρmol/L; mean±SEM, p=0.03, paired t-test). Despite differences in insulin concentration, there were no differences in total glucose appearance (3398±197 vs 3307±343 μmol/kg) or time taken for 25% (33.1±3.3 vs 31.7±3.5 min), 50% (54.6±3.5 vs 54.1±4.7 min) or 75% (82.9±7.1 vs 82.8±5.8 min) of total glucose appearance. The fraction of the glucose dose appearing in the circulation was the same for basal (73±8%) and prandial (75±4%) study days.

Conclusions These results suggest that meal glucose appearance is independent of prandial insulin concentration in people with type 1 diabetes.