Metformin

Question 1

What is the mechanism of action of metformin?

Answer 1

It activates AMP-activated protein kinase. This increases insulin sensitivity and decreases hepatic gluconeogenesis

Question 2

What are the indications for metformin?

Answer 2

First line medical management of type 2 diabetes

Question 3

What is the typical dose of metformin for type 2 diabetes?

Answer 3

500mg TDS or 500mg OD modified release

Question 4

What are the common side effects of metformin?

Answer 4

Nausea and vomiting
Diarrhoea
Taste disturbance

Question 5

What are the important side effects of metformin?

Answer 5

Lactic acidosis

Question 6

What are the cautions for metformin?

Answer 6

Risk factors for lactic acidosis:
- Heart failure
- Concurrent use of drugs that acutely impair renal function

Question 7

What are the contra-indications to metformin?

Answer 7

Acute metabolic acidosis (including lactic acidosis and DKA)

Question 8

What medications does metformin interact with?

Answer 8

ACE inhibitors (increased hypoglycaemic effect)
MAOIs (increased hypoglycaemic effect)

Question 9

How is metformin monitored?

Answer 9

U&Es and eGFR should be performed before commencing treatment. These should be checked annually or every 6 months in patients with renal impairment

Question 10

What should be communicated to patients about metformin?

Answer 10

Metformin should be taken with food

Question 11

Under what eGFR should metformin be stopped?

Answer 11

eGFR < 30