Metformin Counselling – OSCE Guide

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This article provides a step-by-step approach to counselling patients about metformin in an OSCE setting.

Opening the consultation

Wash your hands and don PPE if appropriate.

Introduce yourself to the patient including your name and role.

Confirm the patient’s name and date of birth.

Clarify the purpose of the consultation: “Today you are here to discuss a medication called metformin. Is that correct?”. 

It is important to establish a good rapport and an open line of communication with the patient early in the consultation: “If you have any questions at any point – or if something is not clear – please feel free to interrupt and ask me”.

Make sure to check the patient’s understanding at regular intervals throughout the consultation and provide opportunities to ask questions (this is often referred to as ‘chunking and checking’).

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Patient’s ideas, concerns and expectations

A key component of counselling involves exploring a patient’s ideasconcerns and expectations (often referred to as ICE).

Asking about a patient’s ideas, concerns and expectations can allow you to gain insight into how a patient currently perceives their situation, what they are worried about and what they expect from the consultation. It can sometimes be challenging to use the ICE structure in a way that sounds natural in your consultation, but we have provided some examples for each of the three areas below. 


  • “Have you heard of metformin?”
  • “Before we start, what do you already know about metformin?”
  • “Do you know what metformin is used for?


  • “Is there anything that worries you about taking metformin?”


  • “Is there anything specific you’d like me to discuss or focus on?”
  • “What are you hoping to get out of this conversation about metformin?”

Tip: Establishing the patient’s ideas, concerns and expectations early in the consultation will enable you to focus on the factors that matter most to the patient. This will increase the quality of the consultation and further build rapport between you and the patient.

Patient history

Although the purpose of this station is to counsel the patient, it is a good idea to gather a quick, focused history early in the consultation.

This should include an exploration of the patient’s symptoms and management of their condition, including trials of previous medications, including their impact, compliance and adverse effects. Before prescribing any drug, ask about allergies, contraindications and cautions, other medications the patient is taking, smoking and pregnancy.  

Understanding the patient’s care so far will help you tailor any advice and personalise the information for their specific situation.


Ask the patient if they have any known allergies. If the patient has had a drug reaction previously, ask about the features and severity of the reaction.

An individual’s drug allergy status should be documented in their medical records, and this information should be kept distinct from the details of any adverse drug reactions.1

  • “Are you allergic to any medications?”
  • “Have you reacted to any medications in the past?”

Contraindications and cautions for metformin

Screen for any contraindications to metformin. Metformin should not be prescribed to patients at risk of lactic acidosis:2,3,4

  • Diabetic ketoacidosis (DKA)
  • Hepatic insufficiency
  • Risk of acute kidney injury (e.g. hypovolaemia, shock)
  • eGFR <30
  • Acute alcohol intoxication
  • Any cause of tissue hypoxia: cardiac or respiratory failure, shock, recent myocardial infarction.

Metformin should be withdrawn if these conditions develop.2,3,4

Screen for any cautions to prescribing metformin:

  • Risk of renal impairment (e.g. on nephrotoxic drugs)

In addition, metformin should be prescribed with caution in elderly people.2

  • “Do you know of any reason why you may not be able to take metformin?”
  • “Do you have any problems with your kidneys or liver?”

Drug history

An accurate drug history is essential to identify potential drug interactions.

Medications which may interact with metformin include:

  • Corticosteroids
  • Diuretics (e.g. furosemide)
  • Beta-blockers
  • Hormone replacement therapy: oestrogen, progesterone, testosterone

Ask if the patient is taking any insulin or other anti-diabetic medications, as the risk of hypoglycaemia can be increased when metformin is used in combination.2, 5, 6

  • “Are you currently taking any regular medications or over-the-counter medicines?”
  • “Are you taking any other drugs for your diabetes, or are you on insulin?”

What is metformin and when is it used?

Metformin is a biguanide anti-hyperglycaemic drug. It is used as first-line monotherapy in type 2 diabetes mellitus or combined with other oral anti-diabetic drugs or insulin.

Metformin lowers blood glucose concentrations without causing hypoglycaemia.

Metformin can also be used in the treatment of gestational diabetes, type 2 diabetes in children (aged >8) and polycystic ovary syndrome (unlicensed).2,7,10,11,12,13

“Metformin is a long-term treatment used to manage your diabetes by helping control your blood sugar levels. Metformin is usually the first treatment we try in patients with type 2 diabetes. An advantage of metformin is that it doesn’t cause your blood sugar levels to drop too low.”

How does metformin work?

Type 2 diabetes

Insulin is a hormone made by the pancreas which regulates blood glucose levels, acting as a ‘key’ allowing glucose to enter cells.

Type 2 diabetes is characterised by an insensitivity to insulin (‘insulin resistance’). Instead of entering cells, glucose (sugar) remains in the bloodstream causing high blood sugar levels (hyperglycaemia).

High blood sugar cause symptoms (e.g. thirst, tiredness, and polyuria). Over extended periods, high blood sugar can cause damage to organs, blood vessels and nerves.10,11,13

For more information, see our OSCE guide to explaining a diagnosis of diabetes.

How metformin works

Metformin primarily lowers blood glucose concentrations by reducing hepatic glucose production (called gluconeogenesis) and increasing the ‘insulin sensitivity’ of peripheral tissues, increasing glucose uptake and utilisation.7,10,14

Metformin does not stimulate insulin secretion, so it does not cause hypoglycaemia.7,10,14

The mechanisms underlying these effects are complex and not fully understood. Metformin is involved in activating adenosine monophosphate-activated protein kinase (AMP kinase).10

Metformin lowers your blood glucose levels. It does this by reducing glucose (sugar) released by the liver into the blood and increasing glucose (sugar) uptake by the cells in your body.”

“It is important to control your blood sugar levels as high blood sugar over long periods can damage your nerves and blood vessels. This can present as loss of feeling or pain in your fingers and toes, vision loss, sexual problems, heart disease and an increased risk of stroke.”

How to take metformin

Metformin comes in tablet, liquid and powder forms. It is usually prescribed as a tablet.15

Metformin should be taken at the same time(s) each day. It should be taken with a meal or just after. This will improve gastrointestinal tolerability.

Starting doses of metformin vary, but generally, patients are started on lower doses, which are then titrated to reduce the risk of side effects.

A common example regimen when starting metformin is 500mg once daily with breakfast.2,7,16

“Metformin is usually given in tablet form. It should be taken at the same time each day with food or just after eating.”

“When you start metformin, the dose will be increased slowly. This will reduce the chance of side effects.”

Duration of treatment

Metformin is a long-term medication, and diabetes treatment is usually for life. The patient’s blood sugar levels will be checked regularly, and the metformin dose may be adjusted accordingly.16

“Treatment of diabetes is life-long. After being prescribed metformin, you will likely be taking this long-term. We may need to change your metformin dose depending on your blood sugar levels”.

Types of metformin

Metformin comes in two forms: standard release and slow-release or modified-release. Both forms of metformin act in the same way but have different regimens. Patients are initially started on standard-release metformin.

Patients with troublesome gastrointestinal side effects from standard-release tablets should be trialled on modified-release metformin.

Modified-release tablets release metformin more slowly and evenly than a standard release. This gradual release reduces gastrointestinal side effects. In addition, modified-release tablets do not need to be taken as frequently. The simpler regimen and fewer side effects improve the tolerability of the treatment.16,17

“Some people find the side effects of standard metformin troublesome. It can upset the stomach. If this is the case, we can switch to ‘modified-release/slow-release’ metformin.”

Missed doses

After a missed dose, patients should take the next dose as normal when it is due. Patients should not take two doses together to compensate for a forgotten dose.16

“If you miss a metformin dose, don’t take two doses together to make up for this. Continue to take the next dose as normal.”

Metformin monitoring

Renal function should be checked before starting metformin. If eGFR is less than 30, metformin should not be initiated.

During treatment with metformin, patients with normal renal function should have their eGFR checked annually. Patients at risk of renal impairment should have their eGFR checked twice a year.2, 7

“Before starting metformin, you will need a blood test to check your kidney function. Thereafter, your kidney function will be checked at least annually.”

What are the side effects of metformin?

Like all medicines, there are side effects associated with metformin. Some side effects are more serious than others. Educating patients about the signs associated with serious side effects is important.

Common side effects2,7,10,18

Gastrointestinal upset

Gastrointestinal side effects are most likely to occur after the initiation of treatment and usually resolve spontaneously. Symptoms may include:

  • Nausea
  • Vomiting
  • Diarrhoea
  • Abdominal pain
  • Taste disturbance

“Some side effects of metformin include feeling or being sick, diarrhoea, stomach ache and taste disturbance”

Weight loss

One of the beneficial effects of metformin is that it can cause moderate weight loss. This can be a desirable side effect in overweight and obese patients.4,10,14,19

“Metformin does not cause weight gain, and in some patients, it can cause weight loss”.

Rare but serious side effects

B12 deficiency

Long-term use of metformin, particularly at higher doses, can lead to B12 deficiency. Patients with B12 deficiency may develop anaemia or neurological symptoms.14,18

“Taking metformin for a long time can cause a deficiency in a vitamin called B12. If you start feeling very tired, breathless or faint, or begin experiencing abnormal sensations like pins and needles, you should seek medical help to get your B12 levels checked”.

For more information, see the Medicines and Healthcare Products Regulatory Agency (MHRA) drug safety alert on metformin and B12 deficiency

Lactic acidosis

Lactic acidosis is a rare but potentially life-threatening condition. The onset is insidious with non-specific features, including nausea, vomiting, abdominal pain, diarrhoea, weakness, and lethargy.

Lactic acidosis is more likely to occur in specific situations, including renal insufficiency, dehydration (e.g. severe diarrhoea, vomiting, fasting for surgery), chronic liver disease, hypoxia and alcohol use. Metformin should be stopped if the patient is at risk of lactic acidosis.2,4,7,10

“Seek urgent medical advice if you develop any serious illness, as metformin may need to be stopped due to a rare and serious side effect called lactic acidosis. You may feel very tired, have a fever, feel breathless, experience chest pain, abdominal pain, feel sick or vomit. While taking metformin, drink no more than 2 units of alcohol per day as alcohol can increase the risk of lactic acidosis.”

Metformin should be withheld before and for 48 hours after any scan involving IV contrast media due to the increased risk of renal impairment. This can subsequently lead to metformin accumulation and lactic acidosis.2, 3, 4

“Before any medical scans, inform the staff that you are taking metformin as you may need to stop taking it.”


Unlike other anti-diabetic treatments (e.g. insulin), metformin does not cause hypoglycaemia.

However, if a patient is taking other treatments for diabetes, it is important to educate them about the signs and symptoms of hypoglycaemia so they can recognise these early and act accordingly.4, 10, 18

Typical symptoms of hypoglycaemia include:

  • Hunger
  • Trembling or shaking
  • Sweating
  • Weakness
  • Confusion
  • Difficulty concentrating

“Metformin doesn’t usually cause low blood sugar or hypoglycaemia. But you and your friends and family should be aware of the signs so they can recognise a hypoglycaemic episode if it happens. You may feel hungry, weak, shaky, find it hard to concentrate or become confused”.

Lifestyle advice & follow-up

Metformin works to control blood sugar levels in patients with type 2 diabetes. It is important to make the patient aware that lifestyle changes will help manage their blood sugar levels and weight.19

“Although metformin is a treatment for your diabetes, you can also help control your blood sugar levels through a balanced diet and keeping active.”


Good nutrition is essential in the management of diabetes. Advise high-fibre, low-glycaemic index sources of carbohydrates (e.g. fruit & vegetables).

Patients should try to limit foods high in sugar and salt content. Starchy foods like potatoes, rice, pasta and bread can raise blood glucose quickly. They have a high-glycaemic index and make it harder to manage diabetes. Other starchy foods like wholegrain bread or brown rice have a low-glycaemic index and affect blood sugar levels more slowly.19,20 21

“In type 2 diabetes, there’s no food you can’t eat, but it’s important that your diet is balanced. Eat a variety of fruit, vegetables and pulses. Try to limit starchy foods like potatoes, white bread, and pasta, as these can spike your blood sugar. Minimise the amount of sugar, fat and salt in your diet. It’s important to eat at regular mealtimes and not to skip meals to avoid any ‘hypos.”


Explain to patients that they should exercise regularly, aiming for about 150 minutes weekly. Regular exercise will lower blood glucose levels, reduce cardiovascular risk, and help maintain a healthy weight.19,22

“You should try to exercise for approximately two and a half hours each week. Regular exercise will help you maintain a healthy weight, control blood sugar levels and reduce your risk of heart disease, stroke and cancer.”

Alcohol and smoking

The recommended alcohol limits are 14 units per week, spread over three or more days for both men and women. Advise the patient that alcohol is high in calories, can interfere with their diabetes medication and make hypoglycaemic episodes less obvious.19, 23

“You should drink no more than 14 units of alcohol per week spread over three days or more. When taking metformin, you should drink no more than two units per day. Alcohol is high in calories, can interfere with your diabetes medication and may make hypoglycaemic episodes less obvious.”

If appropriate, advise the patient on the importance of smoking cessation and signpost to smoking cessation services.19

Follow up

It is critical that patients attend follow-up appointments to review blood sugar control and screen for complications. Patients newly diagnosed with type 2 diabetes will have their HbA1c checked every three months, then every six months after it’s stable.

Annually, patients with diabetes will have a ‘diabetic review’ including:19,24

  • Examining the feet (‘foot check’)
  • Diabetic retinopathy eye screening
  • Checking blood pressure
  • Blood tests: cholesterol, renal function, HbA1c

“People with type 2 diabetes have lots of health check-ups and appointments. It is important that you attend these, as this is the best way to lower your risk of complications and help you to control your blood sugar. You will have blood sugar checks (HbA1c) every three months and then every six months after they’re stable. Annually you will have a ‘diabetic review’ this will involve having a look at your feet, checking for damage to your eyes, blood pressure checks and blood tests to look at your cholesterol and kidney function.” 

Closing the consultation

Close the consultation by summarising what you have discussed. This allows you to emphasise the key points of the consultation.

Ask the patient if they have any questions or concerns that have not been addressed.

Finally, thank the patient for their time and offer them a leaflet summarising the key information related to metformin therapy.

Dispose of PPE appropriately and wash your hands.


Holly Elwell

Highly Specialist Pharmacist for Medical Education

Honorary Lecturer in Pharmacology and Prescribing Practice


Dr Chris Jefferies


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