Mechanisms of fasting hypoglycemia and concomitant insulin resistance in insulinoma patients.
To gain further insight into the pathogenesis of fasting hypoglycemia in patients with insulin-secreting adenoma of the pancreas, we studied seven patients affected by insulinoma (age, 42 +/- 7 years; body mass index [BMI], 27 +/- 2 kg/m2) and seven normal subjects. In insulinoma patients, hepatic glucose production (HGP) and glucose utilization (Rd) were evaluated by infusion of 3-3H-glucose at spontaneous fasting plasma glucose concentration, after restoration of euglycemia and during euglycemic insulin clamp (40 mU/m2/min). In insulinoma patients, fasting plasma glucose concentration (2.8 +/- 0.2 v 4.5 +/- 0.1 mmol/L; P < .001), HGP, and glucose Rd (7.8 +/- 1.1 v 12.0 +/- 0.3 mumol/kg/min; P < .01) were lower than in normal subjects, while plasma insulin level was higher (138 +/- 19 v 38 +/- 3 pmol/L; P < .001). In insulinoma patients after attainment of euglycemia (4.7 +/- 0.2 mmol/L) by exogenous glucose infusion, insulin level increased slightly (174 +/- 18 pmol/L; P < .01) and glucose Rd was similar to that of normal individuals (12.8 +/- 0.6 v 12.0 +/- 0.3 mumol/kg/min). During the clamp studies, glucose Rd was lower in insulinoma patients (18.7 +/- 1.2 v 33.8 +/- 3.1 mumol/kg/min; P < .01) despite higher plasma insulin concentration (612 +/- 48 v 420 +/- 12 pmol/L). Therefore, glucose Rd/I x 100 ratio (where I is plasma insulin concentration) was much lower in insulinoma patients (3.1 +/- 0.9 v 8.0 +/- 0.7; P < .01), suggesting a marked degree of insulin resistance.(ABSTRACT TRUNCATED AT 250 WORDS)
Del Prato
S
S
Cattedra di Malattie del Ricambio, University of Padova, Italy.
Riccio
A
A
Vigili de Kreutzenberg
S
S
Dorella
M
M
Avogaro
A
A
Marescotti
M C
MC
Tiengo
A
A
D000293:Adolescent; D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000032:analysis; D005215:Fasting; D005260:Female; D005947:Glucose / Q000378:metabolism; D006728:Hormones / Q000097:blood; D006801:Humans; D007003:Hypoglycemia / Q000209:etiology* / Q000503:physiopathology; D007333:Insulin Resistance; D007340:Insulinoma / Q000150:complications* / Q000378:metabolism / Q000503:physiopathology*; D008099:Liver / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000150:complications* / Q000378:metabolism / Q000503:physiopathology
D001786:Blood Glucose; D006728:Hormones; D005947:Glucose