Immediate-release metformin is an oral diabetes medication. It's approved for people 10 years of age and older with Type 2 diabetes. The medication belongs to the drug class called biguanides. It works best to lower blood sugar levels with a diabetes-friendly diet and exercise plan. Immediate-release metformin comes as a tablet and an oral solution. You take this medication by mouth usually two to three times a day. It's recommended to take each dosage with food to help lessen side effects like diarrhea and nausea.