Biguanides Medication: Indications, Benefits And Precautions


Biguanides Medication

Biguanides are a type of diabetic medication for patients who have type 2 diabetes. This medication works by inhibiting sugar synthesis in the liver, boosting insulin sensitivity, and lowering the amount of sugar absorbed by the intestines.

Biguanides can use their own medication or in combination with other diabetic medicines like insulin and tablets. Many communities recommend starting Biguanides as the initial class of treatment after a Type II Diabetes diagnosis unless contraindicated.

Patients use Metformin in conjunction with other diabetes drugs, such as sulfonylureas. In most countries, metformin is the only biguanide that helps in treating diabetes. This medication is sold under the brand names as:

  • Glucophage (metformin)
  • Glucophage XR (metformin extended-release)
  • Fortamet
  • Glumetza
  • Riomet

In several countries, the diabetic effects of biguanides are documented in traditional herbal medicine. Guanidine, a chemical found in the plant Galea Officinalis, or goat’s rue, is one of the herbal medicine that helps in lowering blood glucose levels.

Although this chemical is first used at the current time period which was later discovered that it causes toxicity and enhances insulin availability.

Working of Biguanides

Biguanides work by converting blocking lipids and amino acids to glucose in the liver. They also activate an enzyme called AMPK, which helps cells in responding to insulin and absorbing glucose from the bloodstream.

Biguanides help in controlling blood sugar on their own or as part of combination therapy with a healthy diet and exercise. Metformin is the only biguanides available currently. It is unlikely to cause low blood sugar (hypoglycemia) unless used with other drugs.

However, it does not cause the pancreas to produce more insulin. There are a few following things you should know before using a biguanide prescription: 

  • Some people lose weight when they use metformin. 
  • Women who are considering taking a biguanide should take great care. 
  • Biguanide medicines may lead you to start menstruation again if you no longer do.  Also, women can get pregnant even if they are using an oral contraceptive while taking metformin.
  • It’s unclear whether biguanides travel via breast milk or if the medicine may harm your unborn child.
  • Before taking a biguanide, tell your doctor if you are pregnant or breastfeeding.

It’s also a good idea to tell your doctor about any other medications you’re taking, including prescriptions and over-the-counter supplements like vitamins and herbal supplements, to ensure that they’re safe to take with metformin.

Biguanides Indications

Biguanides are an oral medication that helps to treat mild to moderately severe noninsulin-dependent diabetes mellitus (Type II) in obese or overweight people over the age of 40 years. The disease needs to be adult-onset for this medicine while administering.

Type 1 Diabetes Mellitus

Metformin reduces the amount of insulin required in people with type 1 diabetes mellitus. According to some associations, using metformin reduces body weight and improves lipid values, but not HbA1c.

According to the REMOVAL trial, metformin may also slow the advancement of atherosclerosis, implying that it may help with cardiovascular disease risk management in type 1 diabetes.

Type 2 Diabetes Mellitus

In people with type 2 diabetes mellitus, many guidelines recommend metformin and lifestyle changes as the first-line treatment to enhance glycemic control.

One can use metformin alone or in conjunction with glucagon-like peptide-1 receptor agonist (GLP-1 RA), sodium-glucose co-transporter inhibitor (SGLT2i), dipeptidyl peptidase-4 inhibitor (DPP4-I), thiazolidinedione (TZD), sulfonylurea (SU), and insulin as a monotherapy or combination therapy. 

You can only continue the biguanides medication, metformin, for as long as it is tolerated well and not contraindicated. All other medications should be used in conjunction with metformin therapy.


The great majority of associations recommend the biguanide medication for pre-diabetes. Patients with prediabetes can combine metformin with lifestyle intervention.

They need to pair it with glucose tolerance (2-h post-load glucose 140–199 mg/dL), fasting hyperglycemia (100–125 mg/dl), or an A1C of 5.7–6.4 percent.

This medication helps to prevent or delay the onset of type 2 diabetes. Although other pharmacological treatments (acarbose, orlistat, and rosiglitazone) have been tested in clinical trials, it appears as the most trustworthy medication.

Gestational Diabetes Mellitus

The first-line therapy for gestational diabetes mellitus is lifestyle changes. If glycemic objectives are not attained, insulin treatment is required to reduce blood glucose.

Otherwise, metformin is used in case the patient is unable to take insulin.  The use of biguanide (Metformin) ability during pregnancy reduces several Controlled Randomized Trials.

In systematic reviews, metformin medication helps in lowering the risk of neonatal hypoglycemia and less maternal weight gain than insulin.

Nonetheless, metformin may increase the prematurity risk slightly and can cross the placenta. As a result, many associations believe that it will be great if doctors avoid the use of metformin as a first-line treatment.

Hence, biguanide medication appears to have a greater benefit in patients over 60 years old with a BMI of more than 35 kg/m2 or women who previously had gestational diabetes mellitus.

Polycystic Ovary Syndrome


Insulin resistance and hyperinsulinemia are common in PCOS patients. PCOS may get signified with time, by showing severe symptoms, like low sex drive, weight changes, excessive hair growth on the body, mood changes, and many more.

Metformin, a part of biguanide medication, is used to treat the metabolic abnormalities associated with PCOS. Metformin has been shown to lower testosterone and insulin levels in women with PCOS, according to a recent meta-analysis. 

Dosage of Biguanides

Metformin is a drug that comes in the form of a tablet or a liquid. Inhaled forms of Metformin are also available. Your doctor will begin by prescribing a low dose and progressively raise it as your body requires. The dosage includes:

  • Metformin doses should range from 500 mg to 2550 mg per day.
  • You should follow each product’s instructions in order for using it safely.
  • It’s fine to keep it at room temperature.
  • You can take it once or three times each day, depending on the form.
  • To avoid side effects, you can take metformin with food.
  • If you miss a dose, instead of double-dosing, take your next dose at the regular time.

Benefits of Biguanides

Metformin, which is one of the popular forms of biguanide, helps to lower blood glucose levels throughout the day. Metformin increases the body’s sensitivity to insulin rather than boosting insulin release, which provides weight-management benefits.

Reduced Risk of Heart Disease

Biguanides, in addition to lowering blood glucose, reduce the risk of heart disease by lowering harmful cholesterol levels in the blood. However, you can also reduce the risk of heart diseases by:

No Participation In Lowering Low Blood Glucose

Biguanides are unlikely to produce low blood sugar when administered alone. However, you can take some measures to lower your blood glucose level as:

  • Eat all your meals
  • Taking of right amount of insulin
  • Stick with your diabetes management plan
  • Recheck your blood glucose level
  • Do proper exercise
  • Maintain a proper diet plan

Possible Weight Loss

Weight loss can be one of the factors of biguanides. It is not a weight-loss medicine, but some studies show that it has little effect on weight loss. You may follow these measures to control it:

  • Eat when you are hungry
  • Drink plenty of water
  • Avoid processed food
  • Don’t skip meals
  • Eat a variety of whole foods

Side Effects of Biguanides

Metformin is unlikely to cause hypoglycemia or weight gain when used as a single therapy. It increases the side effects when the use of medicine with insulin or sulphonylurea increases.

Vitamin Deficiency

In addition, numerous associations recommend that potential vitamin B12 deficiency being evaluated and screened in type 2 diabetes patients who have been on high-dose metformin (more than 2 g/day) for a long time.

The metformin-treated group had a considerably reduced level of this vitamin, according to a meta-analysis of 29 trials.

The following are the results of the study:

  • The medication competes with the absorption of vitamin B12.
  • It has an impact on the intrinsic factor’s functioning.
  • Because it changes bowel movement, it causes bacterial overgrowth.

Gastrointestinal Intolerance

Nausea, bloating, diarrhoea, and abdominal discomfort are common side effects of Metformin, especially when you use it for the first time. Metformin hydrochloride is normally taken orally and is absorbed mostly via the small intestine.

Drug transfer via organic cation transporter 1 allows the concentration inside the enterocyte to reach up to 300 times that of the circulation (OCT1).

Metformin also boosts glucose utilization in the anaerobic cycle and lactate generation in the enterocyte. An increase in lactate production causes negative effects.

Build Up of Lactic Acid 

The kidneys excrete this class of biguanide medication. It happens when it damages the optimal function which might create excessive quantities of metformin circulating in the bloodstream.

This acid causes by high amounts of biguanides in the body. However, this consequence is extremely rare. You can discuss your risk with your healthcare physician.

Allergic Reactions

Metformin causes very few allergic reactions. Hypersensitive asthma patients can use it, without raising the risk of adverse effects such as hospitalizations, asthma-related emergency room visits, or exacerbations.

Even though your doctor should be aware of the occurrence of cutaneous allergic responses.

Precautions of Biguanides

In addition to the standard testing for diabetes, your doctor will firstly test your kidney function. This is to estimate the glomerular filtration rate, or EGFR (Estimated Glomerular Filteration Rate), before prescribing metformin for the first time.

Below are some following treatment guidelines according to many associations:

  1. People with advanced kidney disease should avoid using metformin. However, strong data currently suggests that metformin along with careful monitoring is useful for those with mild kidney impairment as well as some people with moderate kidney function.
  2. Before starting metformin, tell your doctor if you drink alcohol frequently or in large amounts at once. It is because alcohol reduces blood sugar levels but raises the risk of lactic acidosis as well as severe glucose imbalances. 
  3. It is indeed important for your doctor to know if you easily become dehydrated during exercise or for other reasons because dehydration raises the risk of lactic acidosis.
  4. Stomach pains, nausea, and/or vomiting, unusual muscle discomfort, tiredness or fatigue, a slow or irregular heartbeat, and breathing difficulties are all warning indications of lactic acidosis. Seek medical help right away if you have any of these symptoms.
  5. Reassurance was given to pregnant women that metformin is generally safe during pregnancy and may even prevent in reducing difficulties. According to studies, women with PCOS benefit from continuing to take metformin during pregnancy.
  6. Metformin users should continue to take their prescription as directed until their doctor recommends an alternative treatment if one is available. Also for those with type 2 diabetes stop taking metformin without finding a replacement for substantial health risks.


Similar to weight loss, biguanides reduce hyperinsulinemia. Sulfonylureas and, in particular, exogenous insulin aggravate it to a great extent.

However, eliminating lactic acidosis risks can be beneficial if you are following dosing directions and contraindications strictly. Hence, in this article, you will also get to know the benefits, indications, and precautions that should be taken for biguanide medications.

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