Thiazolidinedione (TZD) and its pharmacologically active derivatives can be used in combination with agonists of glucagon-like peptide-1 (GLP-1), to treat non-insulin dependent diabetes mellitus, optionally with other therapies, by improving glycemic control while minimizing side effects, such as heart hypertrophy and elevated fed-state plasma glucose, which are associated with both TZD and GLP-1 monotherapies. Thus, the co-administration of TZD and GLP-1 helps regulate glucose homeostasis in Type II diabetic patients.