Abstract
The effect of phenformin on fuel homeostasis and on gluconeogenesis from protein was
studied in 8 normal subjects who underwent two 4-day fasts 8-12 weeks apart. Each
person received placebo or phenformin 50 mg every 12 hours for 3 days before and during
the fasts. Circulating glucose, lactate, pyruvate, free fatty acid and ketone levels
as well as urinary nitrogen excretion observed during placebo and phenformin treatment
were not significantly different from each other. The lack of an effect of phenformin
on urinary nitrogen excretion and plasma glucose level strongly suggests that gluconeogenesis
from amino acids was unaltered by phenformin in these fasting subjects. The present
findings are at variance with those by other authors which may be related to differences
in methodology.
Key words
Biguanides - Gluconeogenesis - Nitrogen Excretion - Starvation
