Vethakkan S R, Walters J M, Gooley J L, Boston R C, Ward G M
Department of Endocrinology and Diabetes, St Vincent's Health Melbourne, Victoria, Australia.
Clin Endocrinol (Oxf). 2009 Jan;70(1):47-52. doi: 10.1111/j.1365-2265.2008.03287.x. Epub 2008 Apr 28.
The unmodified frequently sampled intravenous glucose tolerance test (FSIGT) has not previously been used to assess insulin/glucose kinetics in patients with insulinoma.
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.
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.
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).
Insulin sensitivity improves after excision of an insulinoma. Glucose effectiveness is not influenced by chronic hyperinsulinaemia and hypoglycaemia.
