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Question 444
Pharmacology → General
Classification
Question
SSBAQuestion Header
A woman with insulin resistance is treated with metformin. Which pharmacological feature best explains why metformin lowers elevated glucose without characteristically producing hypoglycaemia when used therapeutically?
Question Stem
Select the single best answer.
Options
A
It directly releases stored insulin irrespective of islet function
B
It blocks glucose utilisation by skeletal muscle
C
It stimulates glucagon release during fasting
D
It irreversibly inhibits intestinal glucose absorption
E
It improves insulin sensitivity and requires endogenous insulin activity
Explanation
Metformin is a biguanide whose effects are mediated largely by improvement in insulin resistance, including improved hepatic and muscular glucose utilisation. Its action depends on the presence of endogenous insulin and therefore requires residual islet-cell function; it reduces elevated glucose without characteristically causing hypoglycaemia.
Option Validity
A) Metformin improves insulin sensitivity rather than directly stimulating insulin secretion.
B) Metformin improves rather than blocks muscular glucose utilisation.
C) Stimulation of glucagon release is not a mechanism of metformin.
D) Irreversible inhibition of intestinal glucose absorption is not the mechanism of metformin.
Further Reading
Saxena R. Textbook for MRCOG-1. Chapter 12: Pharmacology. Drugs Interfering with Glucose Metabolism, p.347.