The subject invention provides compositions and methods for treating diabetes in patients. In a preferred embodiment, the invention provides compositions methods for treating diabetes and/or preventing or alleviating complications associated with diabetes. Specifically exemplified herein is the concurrent administration of a cysteamine compound with at least one additional therapeutic agent to prevent and/or treat diabetes as well as prevent and/or treat complications associated with diabetes. In a preferred embodiment, oral administration of cysteamine hydrochloride with Metformin to a patient diagnosed with diabetes can substantially regulate the patient's glucose metabolism and insulin sensitivity.