Decreased production of glucose from the liver

This is correct! Metformin activates AMPK-dependent protein kinase (AMPK) due to a reduction in cellular energy stores. AMPK reduces hepatic glucose production (gluconeogenesis) through inhibition of expression of genes that are important in gluconeogenesis. Remember that gluconeogenesis contributes to hyperglycaemia in diabetes.

Further Developments

Five years later, Mr. Green reports progressive exertional dyspnoea over several months, now short of breath after one flight of stairs, with new orthopnoea requiring two pillows and intermittent paroxysmal nocturnal dyspnoea. The medical notes show lack of follow-up over the past 18 months, which Mr. Green explains were due to a job change. He reports that his home blood pressure readings have been on the high side.

On examination his blood pressure is 132/78 mm/Hg and his BMI is now 30 kg/m²; physical examination shows bibasilar rales. Mr. Green is scheduled for an echocardiogram and invasive coronary angiography with a contrast agent to assess for obstructive coronary artery disease.

What is the most appropriate advice for Mr. Green for use of metformin during this time?