Inhalation of Insulin (Exubera) Is Associated With Augmented Disposal of Portally Infused Glucose in Dogs

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Abstract
The results of the present study, using the conscious beagle dog, demonstrate that inhaled insulin (INH; Exubera) provides better glycemic control during an intraportal glucose load than identical insulin levels induced by insulin (Humulin) infusion into the inferior vena cava (IVC). In the INH group (n = 13), portal glucose infusion caused arterial plasma glucose to rise transiently (152 ± 9 mg/dl), before it returned to baseline (65 min) for the next 2 h. Net hepatic glucose uptake was minimal, whereas nonhepatic uptake rose to 12.5 ± 0.5 mg · kg−1 · min−1 (65 min). In the IVC group (n = 9), arterial glucose rose rapidly (172 ± 6 mg/dl) and transiently fell to 135 ± 13 mg/dl (65 min) before returning to 165 ± 15 mg/dl (125 min). Plasma glucose excursions and hepatic glucose uptake were much greater in the IVC group, whereas nonhepatic uptake was markedly less (8.6 ± 0.9 mg · kg−1 · min−1; 65 min). Insulin kinetics and areas under the curve were identical in both groups. These data suggest that inhalation of Exubera results in a unique action on nonhepatic glucose clearance.