Abstract
Objective: Insulinoma causes fasting hypoglycaemia due to inappropriate insulin secretion. The
diagnosis of insulinoma is based on Whipple's triad during a supervised fasting test.
The aim of our study was to evaluate retrospectively the percentage of positive 48-hour
fasting tests in a large series of patients with insulinoma.
Design, Patients and Methods: In a retrospective study, we identified 39 patients (24 females, 15 men; average
age 47 years [range 12-78 years]) with insulinoma. Sixteen patients were diagnosed
by spontaneous hypoglycaemia. Twenty-three patients with insulinoma were tested with
a 48-hour fasting test and compared to 31 healthy controls who had a negative fasting
test and were followed up for at least two years.
Results: The fast was terminated due to neuroglycopenic symptoms in 4 patients (17.4%) at
the 12th hour, in 17 patients (73.9%) at the 24th hour, and in 22 patients (95.7%)
at the 48th hour. One patient with insulinoma had no neuroglycopenic symptoms, but
was diagnosed by glucose and insulin levels during the 48-hour fast. Healthy controls
had significantly higher blood glucose and lower insulin levels, and a lower insulin-glucose
ratio than patients with insulinoma at the end of the fast.
Conclusions: In conclusion, the 48-hour fasting test was successful in the diagnosis of insulinoma
in 95.7% of patients. In this series we did not observe a need for fasting beyond
48 hours.
Key words
Insulinoma - glucose - insulin - neuroendocrine tumour - diagnosis - MEN - fasting
test
References
Correspondence
marcus.quinkler@charite.de
