Is there any difference between taking metformin before or after meals, and what is the optimal dosage?

In the treatment of type 2 diabetes, GLP-1 agonists and SGLT-2 inhibitors have surpassed metformin due to their greater cardiovascular benefits. However, as the "old man" among glucose-lowering drugs, metformin is still active in the front line of glucose-lowering treatment because of its significant glucose-lowering effect, good safety, and low price.

Many people have asked Huazi, when taking metformin, how to choose the dosage form? Does taking it before or after meals affect the efficacy of the drug? I heard that metformin has an "optimal dose", what is it?

1. About the dosage form of metformin

Metformin is mainly divided into three dosage forms, namely ordinary dosage form, enteric-coated dosage form and sustained-release dosage form . As long as the dosage is the same, no matter which dosage form is chosen, the effect of the drug will not be much different. The difference in dosage form is mainly in the incidence of adverse reactions.

A common adverse reaction of metformin is gastrointestinal irritation , and symptoms such as nausea, vomiting, diarrhea, constipation, indigestion, and abnormal taste may occur when taking it.

Ordinary dosage forms disintegrate rapidly in the stomach to release the drug, which is highly irritating to the digestive tract and causes many adverse reactions.

Enteric-coated dosage forms do not disintegrate in gastric acid and only release the drug after entering the alkaline environment of the small intestine. They cause less irritation to the digestive tract and have fewer adverse reactions.

After the sustained-release dosage form enters the digestive tract, it continues to release the drug slowly, causing minimal irritation to the digestive tract . The blood drug concentration is also more stable and the adverse reactions are minimal.

2. Should Metformin be taken before or after meals?

The time of taking the drug does not affect the efficacy of metformin, but mainly affects the adverse reactions.

It is recommended that ordinary dosage forms be taken with food , or immediately after a meal , so that the drug and chyme are mixed together to reduce direct irritation to the digestive tract.

It is recommended to take the enteric-coated dosage form on an empty stomach before meals . This can reduce the residence time of the drug in the stomach and prevent the alkaline substances in the food from releasing the drug prematurely, allowing the drug to quickly reach the small intestine and be released.

It is recommended that sustained-release dosage forms be taken with food or after meals , so that the drug can mix with the chyme, prolonging its residence time in the digestive tract and exerting a sustained-release effect.

3. Optimal therapeutic dose of metformin

The minimum effective dose of metformin is 500 mg per day, the optimal effective dose is 2000 mg per day , and the maximum dose is 2550 mg per day.

Metformin is usually taken at a low dose, which is then doubled every two weeks until the optimal effective dose is reached . For example, 500 mg is taken daily in the first and second weeks, 1000 mg is taken daily in the third and fourth weeks, and 2000 mg is taken daily starting from the fifth week.

This gradual increase in dosage allows the body to adapt to the drug and minimizes the adverse gastrointestinal reactions caused by metformin.

4. What should you pay attention to when taking medicine?

If you choose the ordinary dosage form , it is recommended to divide the total daily dose into 2 to 3 times and take it with meals .

If you choose the enteric-coated formulation , it is recommended that the total daily dose be divided into 2 to 3 times and taken on an empty stomach before meals .

If you choose a sustained-release dosage form , when the daily dose is less than 1000 mg , you can take it at dinner or after dinner ; when the daily dose is 2000 mg , it can be divided into two times, taken with meals at breakfast and dinner respectively .

Long-term use of metformin may cause vitamin B12 deficiency. It is recommended to check the vitamin B12 level once a year , especially for type 2 diabetic patients with anemia and peripheral neuropathy. More attention should be paid. If vitamin B12 deficiency is found, appropriate supplementation can be taken.

In summary, the time of taking metformin does not affect the effect of the drug, but it will affect the adverse reactions of the drug. Choose a sustained-release dosage form, which has the least adverse reactions when taken with meals. The best effective dose of the drug is 2000 mg per day, but starting with a small dose and gradually increasing the dose can minimize the adverse reactions of the drug.

Drugs must be used under the guidance of a doctor. If you have any questions about medication, please consult a doctor or pharmacist. I am pharmacist Huazi, welcome to follow me and share more health knowledge.