Let's take a minute to talk about your medication. 
This is metformin ER. It helps to treat diabetes by lowering blood sugar and helping the body to better respond to insulin. Controlling your blood sugar is important. Over time, it can postpone or prevent serious health problems. Metformin ER may have other uses too. 
Metformin comes in many forms; you were prescribed the extended-release tablet. You should take it exactly how your doctor tells you to. You should take metformin ER with meals to help lessen stomach upset. Your healthcare team will work to determine the best dose for you and how often you should take it. It is important to swallow the tablet whole, and do not crush or chew it. For more information regarding how to take this medicine and what to do if you miss a dose, read the "Patient Information Sheet".
Most people tolerate this medicine well. Common side effects include an upset stomach, nausea, and diarrhea. It can also cause a metallic taste in your mouth. These effects are normal if they are mild and should go away after a few weeks. Metformin ER is not likely to cause low blood sugar, but this could happen if you also take other medicines for diabetes. Low blood sugar can make you feel shaky, irritable, or lightheaded. Ask your doctor about your risk of low blood sugar, and what to do if it happens. If these or other side effects become reasons you want to stop taking this medication, please talk to your healthcare team. 
As with any medicine, rare but more serious side effects could occur. With metformin ER, this includes a rare condition called Lactic Acidosis. You should read the patient information sheet to know which symptoms to watch for and when to report changes. Your healthcare team will follow your condition closely and may order blood tests.
Metformin ER can interact with other medicines. You should check with your doctor or pharmacist before taking any other medicines, herbal remedies, or vitamins. Also, you should limit alcohol intake. 
Women should talk to their doctors before becoming pregnant or breastfeeding while taking this medication. You should know that metformin ER can increase the risk of unplanned pregnancy. Women should talk to their doctors about which birth control methods are right for them. 
For best results with metformin ER, be sure to follow your doctor's advice about diet, exercise, and checking your own blood sugar.