Biguanidas How do they work? Benefits, Side Effects and Mechanisms of Action

Drug for Type 2 Diabetes

Biguanides are a classification of oral diabetes medications used to treat type 2 diabetes, of which metformin is the generic brand. These antidiabetic medications belong to the family of insulin-resistant drugs.

These drugs work by affecting the production of glucose that comes from digestion.

They do not cause hypoglycemia and even help lose weight and reduce cholesterol levels. They are the most prescribed medications for type 2 diabetes.

Research on its effects in reducing blood glucose levels led to the development of less toxic derivatives.

The biguanides were derived from the French Lila for the first time. Some herbal remedies may include this plant, but if you are using medications for diabetes, you should be cautious due to the interactions.

Other types of biguanides were developed but withdrawn from the market. These include phenformin, which was introduced in 1957 at the same time as metformin but was withdrawn in the late 1970s because it was associated with a high risk of lactic acidosis.


In addition to diabetes, other types of biguanides are used as antimalarial drugs.

Unlike insulin, biguanides come in tablets or syrup, while insulin is given only by injection (for the time being).

How do Biguanides work for diabetes?

Metformin works to control the amount of sugar in the blood. It does not affect the amount of insulin it produces, but it increases insulin sensitivity.

This helps your cells to take glucose for use as energy, decreases the production of glucose in the liver, and reduces the concentration of glucose in the bloodstream.

The use of glucose in the intestines produces lactic acid, which is processed by the liver but can lead to the side effect of lactic acidosis.

Metformin does not cause clinical hypoglycemia, which is advantageous over other diabetes medications.

It also does not cause weight gain and has sound effects reducing some cardiovascular risk factors.

Metformin is often prescribed for type 2 diabetes once changes in lifestyle alone can not control the disease. It is an oral medication that can be taken as a tablet or liquid.

Depending on the form, it is taken one to three times a day. There are extended-release forms, as well as forms to be taken with meals. The instructions for the safe use of each product must be followed.

As diabetes progresses, insulin injections may be needed to control blood sugar levels, and metformin can still be used to improve the body’s ability to use insulin.

Who are the Biguanides suitable for?

Metformin is generally appropriate for most people with type 2 diabetes as the first line of medication if lifestyle changes do not yield the desired results.

Metformin can be taken alone, as monotherapy, or in addition to other oral or injectable diabetes medications. It can also be prescribed in combination with insulin for people with type 1 diabetes who have signs of insulin resistance.


By reducing the effect of increased blood glucose in the liver, metformin helps lower blood glucose levels throughout the day.

Instead of stimulating the release of insulin, metformin increases the body’s sensitivity to insulin and therefore has benefits for weight control.

Side effects

Biguanides can cause secondary digestive effects, such as diarrhea or dyspepsia, which in most cases return over time.

They can also, in rare cases, promote a poor absorption of vitamin B12. These treatments are contraindicated in patients with risk of acidosis, the presence or risk of heart failure, or respiratory disease.

Remember that treatment should also be stopped before surgery that requires general anesthesia.

In monotherapy, metformin users are unlikely to experience hypoglycaemia or weight gain. However, the risk of these side effects increases if the medication is taken together with insulin.