- Patients with co-morbidities such as congestive heart failure, liver disease, and those who had undergone recent surgical procedure were excluded from the study. Other types of patient excluded from the study were: patients on insulin or whose oral hypoglycaemic drug therapy does not include metformin, patients who take alcohol, patients who were on cimetidine, furosemide, nifedipine, ciprofloxacin, rifampicin, anti-retroviral therapy or any other medication with known interactions with metformin. Patients who smoked were also excluded.