Metformin lowers blood glucose (sugar) in your body by lowering liver glucose production, reducing intestinal glucose absorption and improving how well your own insulin works.
Metformin (brand name: Glumetza) in the biguanide drug class, is usually the first drug used to help control blood sugar in people with type 2 diabetes. It helps to lower blood sugar throughout the day and after eating. It works best when used in addition to diet and exercise.
Specifically, metformin, when used with diet and exercise, is approved by the FDA for blood sugar control in the treatment of type 2 diabetes in adults and children 10 years of age and older.
It comes as an oral an oral tablet and may be used in combination with insulin or other medications. Most people use the generic, more affordable version of metformin.
Metformin is well-tolerated by most people and does not usually cause weight gain. It does not trigger the pancreas to make or release more insulin so it doesn't usually cause low blood sugar (hypoglycemia) when used alone. You may experience low blood sugar if it used with other diabetes treatments like insulin or sulfonylureas.
Related: Metformin Precautions and Side Effects (in more detail)
Diabetes complications due to high blood sugar can lead to damage in your nerves, and result in harm to small and large vessels in your body. Managing your blood sugar can help lower the risk of complications like nerve damage, a heart attack or stroke.
Long-term and potentially life-threatening diabetes complications may occur such as:
- heart disease and stroke
- high blood pressure
- blindness due to diabetic retinopathy in the eyes
- kidney disease requiring dialysis or transplant
- nervous system and nerve damage (neuropathy)
- lower-limb amputations
How does metformin work when you eat sugar?
You get glucose (blood sugar) from the food and drinks you consume. Metformin helps to make the body more sensitive to insulin so cells can absorb the glucose and make the energy the body needs.
When your blood sugar rises, your pancreas (an organ in your body) releases insulin. Insulin is a hormone that helps to shift blood sugar into your cells to produce energy needed by your body.
Having too much glucose in the blood can cause insulin to work poorly, leading to a further accumulation of glucose (known as insulin resistance). Insulin resistance usually does not have any specific symptoms and can lead to type 2 diabetes. Metformin helps to lower insulin resistance.
Weight loss and exercise can also help to reverse insulin resistance and prevent the onset of type 2 diabetes.
Risk factors for type 2 diabetes include:
- age over 35
- overweight or obese
- family history of diabetes
- inactivity and lack of exercise
- fat distributed primarily to the stomach area
- non-caucasian
- history of gestational diabetespolycystic ovary syndrome.
Is metformin used for prediabetes?
Prediabetes means your blood sugars (glucose) are high, but not high enough for you to be officially diagnosed with diabetes. People with prediabetes may also have insulin resistance. Doctors sometimes refer to prediabetes as impaired glucose tolerance (IGT) or impaired fasting glucose (IFG).
Metformin has been used successfully in patients with prediabetes to help lower blood sugars; however, this use is not approved by the FDA and is considered off-label. “Off-label" uses are those that are not approved by the FDA and are not found in the package labeling but it may be an accepted and well-researched use.
Your doctor can take a history and physical and complete lab testing to determine your prediabetes or type 2 diabetes status.
While prediabetes may not always have symptoms, symptoms of type 2 diabetes may include:
- excessive thirst
- frequent urination
- blurred vision
- extreme fatigue
- frequent infections
- slow healing cuts or bruises
- numbness in hands and feet
- darkened skin areas
How much weight can I lose with metformin?
Many people with type 2 diabetes have insulin resistance and need to lose weight. One way for people to lose weight is gradually through a combination of a healthy diet and regular exercise, along with required medications.
Large studies have looked at weight loss in patients taking metformin, and weight loss is variable.
- For most people, metformin is considered "weight neutral", meaning they do not gain or lose significant amounts of weight, in contrast to the weight gain that often occurs with insulin or sulfonylurea treatment.
- In some studies, patients have lost up to 2.9 kg (6.4 pounds), but in other studies only a 0.6 kg (1.4 pounds) weight loss was seen.
For more information: Does metformin cause weight loss?
In general, while metformin is a useful drug to control blood sugar in diabetes, weight loss due to metformin may not be enough. You should also use an appropriate diet and exercise program for weight control in type 2 diabetes, as recommended by your doctor.
This is not all the information you need to know about metformin for safe and effective use and does not take the place of your doctor’s directions. Review the full product information and discuss this information and any questions you have with your doctor or other health care provider.