Specific Inhibition of Gluconeogenesis by Biguanides

Abstract

POSSIBLE schemes for the mechanism of the hypoglycaemic action of biguanides have raised considerable controversy in recent years. The possibility that these drugs may act through inhibition of oxidative phosphorylation, which may increase the glucose uptake of peripheral tissues¹, has been frequently emphasized^2–5, but experiments on the kinetics of glucose loads⁶ as well as the demonstration that no correlation exists between the hypoglycaemic effect of various biguanides and their inhibitory action on oxidative phosphorylations^7,8 did not support this hypothesis. Moreover, it is now well established that the biguanide drugs have no effect on the glycaemia of normal animals and men, and that their action is restricted to the diabetic and fasting animal. Thus it appeared reasonable to assume that they may interfere with one or more metabolic pathways which are widely different in the normal and diabetic organism. One of these is the gluconeogenetic pathway, resulting in the synthesis of glucose from metabolites containing three or four carbon atoms, including amino-acids. The possibility that such a mechanism may explain the anti-diabetic action of at least two biguanides (phenylethylbiguanide (PEBG) and dimethylbiguanide (DMBG)) has been investigated.