Pharmaceutical dosage forms, comprising insulin, a delivery agent that facilitates transoprt a therapeutically effective amount to the bloodstream and a biguanide, such as metformin, are disclosed for oral administration to a patient for the treatment of diabetes. Also disclosed are methods for achieving improved glucose tolerance and glycemic control in a diabetic mammal without any statistically significant increase in weight, risk of hypoglycemia or hyperinsulinemia, and the need for monitoring blood glucose concentrations or HbA1c levels, and methods for reducing the incidence and/or severity of one or more disease states associated with chronic dosing of insulin for prophylactically sparing p-cell function or for preventing ß-cell death or dysfunction in a mammal with impaired glucose tolerance or early stage diabetes mellitus and for long-term protection from developing (or delaying the onset of) overt or insulin dependent diabetes in a mammal with unpaired glucose tolerance or early stage diabetes.
