Metformin is used to treat type 2 diabetes. Thanks to years of experience, metformin is a reliable agent for lowering elevated blood glucose levels in diabetes mellitus. Meanwhile, this agent is also recommended for certain forms of cycle disorder. But some contraindications and side effects must be taken into account so that metformin can be taken safely. Metformin is completely unsuitable for patients with type 1 diabetes.
Effect of metformin
Metformin lowers blood glucose levels and improves the body’s utilization of sugar. In addition, this drug shuts down the body’s own sugar production and hinders sugar absorption from the intestines into the blood. It is suitable for patients with type 2 diabetes when other therapeutic approaches have been exhausted. In particular, overweight patients for whom dietary measures and exercise have no effect can benefit from the action of this active ingredient. Experience shows that many patients lose weight precisely at the beginning of taking metformin. Metformin, which belongs to the group of biguanides, is one of the longest on the market antidiabetic drugs and is extremely reliable. It is often used alone initially and only combined with other medications if it is not successful. Metformin is also said to have cardioprotective and vasoprotective properties. A major advantage over other blood glucose-lowering medications is the low risk of hypoglycemia.
Metformin in PCOS
Another use of metformin is for cycle disorders associated with polycystic ovary syndrome (PCOS), which is often associated with diabetes mellitus. Metformin can be used to treat both the cycle disorders and the high blood glucose levels, but it is not yet approved for this use in Germany. Thus, the cost of metformin must normally be borne by the patient in an off-label use.
Metformin in pregnancy and lactation
Diabetes patients taking metformin who wish to have children or are already pregnant should discontinue metformin and switch to insulin. Only in exceptional cases can metformin therapy be continued during pregnancy. The same applies to diabetes that only occurs during pregnancy (gestational diabetes). There are no restrictions for nursing mothers, and metformin can be taken after consultation with the attending physician.
Dosage of metformin
Metformin is a prescription drug. It is best to discuss which dosage is appropriate with your doctor. It is available in film-coated tablet form and is therefore taken orally, preferably before or with meals. Metformin is offered in dosage increments of 500, 850, and 1000 milligrams. For more information, see the package insert.
Side effects of metformin
The most common side effects of metformin manifest as gastrointestinal symptoms: Nausea, vomiting, diarrhea, and abdominal pain are among the side effects that are very common. Also worth mentioning are taste changes, such as a metallic taste in the mouth, which together with the former side effects can cause loss of appetite. Very rare, but highly dangerous, is lactic acidosis. Due to an overdose of metformin or when the kidney is overloaded, the active ingredient accumulates in the body, leading to a derailment of the acid-base balance. The symptoms of lactic acidosis are very similar to the normal side effects of metformin: nausea with vomiting. These are often joined by other gastrointestinal complaints, muscle pain, cramps, and accelerated breathing. In this case, a doctor should be consulted immediately.
Contraindications of metformin
Some chronic conditions prohibit the use of metformin because they either interfere with its metabolism or increase the risk of lactic acidosis. This is the case with heart failure, any conditions that impair lung function (COPD, asthma), liver dysfunction, and impaired renal function. However, according to recent studies, people with moderately impaired kidney function (grade 3b) can be treated with metformin in consultation with their doctor. Further information can be found on the website of the German Federal Institute for Drugs and Medical Devices (BfArM).Circumstances that put a strain on the kidney should also always be reason to reconsider taking metformin. Such circumstances may include, for example, severe vomiting, diarrhea or serious infections. During pregnancy, metformin should also be discontinued and switched to another preparation. Insulin injections, for example, are an option. In combination with alcohol, metformin carries an enormously high risk of lactic acidosis. Alcohol consumption should therefore be refrained from or minimized.
Metformin and surgery
Another special feature of metformin is its handling in the case of general or spinal anesthesia, for example, during surgery. Metformin must be discontinued two days before surgery, and renal function must be checked before reinsertion. The same applies to X-ray examinations with iodine-containing contrast media. Metformin must not be taken before the examination and for up to 48 hours afterwards. Again, clarification of renal function is required after the examination.
Interactions of metformin
In combination with some other medications, the effectiveness of metformin is decreased. Examples include corticosteroids (cortisone), diuretics (diuretics), and some medications for asthma (beta-sympathomimetics). The blood sugar-lowering effect of metformin is increased by antihypertensive drugs such as ACE inhibitors. Alcohol-containing medications (for example, some cough suppressants) and iodine-containing contrast media carry the risk of lactic acidosis in combination with metformin and should therefore be taken with caution. In the case of the contrast agent, metformin must even be discontinued for a time.
Metformin: What to watch out for
Metformin is a good drug for the treatment of type 2 diabetes and can permanently and reliably lower blood glucose levels if some special considerations are taken into account:
- Metformin is suitable for patients with type 2 diabetes in whom dietary and exercise measures have shown no effect.
- Its advantage is the low risk of hypoglycemia.
- The metformin is excreted through the kidneys, kidney function should be checked at least once a year.
- Metformin must be discontinued before surgery and X-ray examinations with contrast administration. Before taking again, the kidney function must be checked.
- Important contraindications are pregnancy and increased alcohol consumption.
