ENDOGENOUS PRODUCTION AND PERIPHERAL USE OF GLUCOSE IN PATIENTS WITH INSULINOMA

Endogenous glucose production (EGP), glucose clear ance and insulin se nsitivity were measured in 5 subjects with insulinoma before and 3 to 6 months after surgical resection of the tumour. Endogenous glucose pr oduction and glucose clearance were evaluated by infusion of [6,6 D-2] glucose, and insulin sensitivity was determined by a euglycaemic hype rinsulinaemic glucose clamp. The patients served as their own controls . The postabsorption blood glucose level was low before treatment (0.5 1 +/- 0.01 g/l) and EGP was 1.86 +/- 0.10 mg kg(-1) min(-1) (normal va lue: 2.2 to 2.6 mg kg(-1) min(-1)), whereas the insulin level was rela tively high (16.4 +/- 1.6 mU/l). After surgical resection of the insul inoma, the blood glucose level rose to 0.94 +/- 0.02 g/l and EGP to 2. 33 +/- 0.04 mg kg(-1) min(-1), whereas the insulin level fell to 6.4 /- 0.5 mU/l. Glucose meta belie clearance in the fasting state was 3.6 8 +/- 0.21 mg kg(-1) min(-1) before and 2.46 +/- 0.09 (n = 2.44 to 3.4 6 ml kg(-1) min(-1)) after surgery. Clamp dose-response curves were sh ifted to the left and insulin sensitivity was improved after surgery. These data suggest that chronic hyperinsulinaemia is associated with i nhibition of endogenous glucose production, a rise in basal glucose cl earance and a slate of insulin insensitivity during the clamp.