The present invention is directed to methods and formulations for treating chronic constipation. The methods and formulations include, but are not limited to, methods and formulations for delivering effective concentrations of metformin for treating chronic constipation and further comprise at least one pharmaceutically acceptable ingredient to control the release of the metformin, wherein following administration, the release of metformin is distal to the gastrointestinal sites to achieve systemic absorption of metformin. The invention is also directed to treating constipation as a symptom associated with other diseases and conditions such as irritable bowel syndrome.