Application of the intravenous glucose tolerance test and the minimal model to patients with insulinoma: insulin sensitivity (Si) and glucose effectiveness (Sg) before and after surgical excision.
BACKGROUND
The unmodified frequently sampled intravenous glucose tolerance test (FSIGT) has not previously been used to assess insulin/glucose kinetics in patients with insulinoma.


OBJECTIVE
To measure insulin sensitivity (Si) and glucose effectiveness (Sg) by means of the FSIGT in patients with insulinoma, before and after surgical removal of the tumour.


METHODS
FSIGTs were performed in five patients, before and approximately 3 months post-surgery, and in 11 controls. Si and Sg were estimated using Minimal Model computer analysis of dynamic glucose and insulin data.


RESULTS
Si was lower in insulinoma patients before, compared with after surgery (3.37 +/- 0.62 vs. 6.24 +/- 1.09 SE [x10(-4)] min(-1)microU(-1) ml, P < 0.05). Sg was similar in patients pre- and post-surgery (3.0 +/- 0.67 vs. 2.4 +/- 0.6 [x10(-2)] min(-1), NS).


CONCLUSIONS
Insulin sensitivity improves after excision of an insulinoma. Glucose effectiveness is not influenced by chronic hyperinsulinaemia and hypoglycaemia.
Vethakkan
S R
SR
Department of Endocrinology and Diabetes, St Vincent's Health Melbourne, Victoria, Australia. shireene.vethakkan@gmail.com
Walters
J M
JM
Gooley
J L
JL
Boston
R C
RC
Ward
G M
GM
D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000378:metabolism*; D005260:Female; D005951:Glucose Tolerance Test / Q000379:methods; D006801:Humans; D007333:Insulin Resistance; D007340:Insulinoma / Q000175:diagnosis* / Q000601:surgery; D008297:Male; D008875:Middle Aged
D001786:Blood Glucose