• Combined endpoint of all cause mortality and all cause hospitalization at 6 months
  

• Individual components of the primary outcome (ie death or hospitalization)
  
• Change in A1c
  
• Change in 6 minute walk
  
• Change in Health Related Quality of Life
  
• Development of Lactic Acidosis
  

Inclusion Criteria:

• All subjects with physician-diagnosed symptomatic heart failure (NYHA class I, II, III, IV) and type 2 diabetes.

A diagnosis of type 2 diabetes defined as:

• a previous physician diagnosis of type 2 diabetes as documented in the subject's clinical record or;
• receiving oral antihyperglycemic agents or;
• a new diagnosis of type 2 diabetes during the visit within the heart failure clinic or hospital based on a fasting blood glucose ≥7.0 mmol/L or random blood glucose ≥11.1 mmol/L accompanied by acute metabolic decompensation or 2 hour plasma glucose in a 75 gram oral glucose tolerance test ≥11.1 mmol/L.

Exclusion Criteria:

• subjects currently receiving greater than 1500 mg of metformin therapy per day
• subjects who are unwilling to change their antidiabetic regimens;
• subjects receiving insulin therapy;
• serum creatinine ≥ 180 μmol/L;
• A1c < 7.0 percent;
• inability to communicate (language barrier);
• dementia/mental illness;
• age < 18 years;
• subjects unwilling to complete self-monitoring of serum blood sugars during the trial period.
• those participating in another heart failure or diabetes clinical trial involving medication;
• severe comorbidities or foreshortened life expectancy;
• subjects who do not provide written informed consent to participate.