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Sodium-glucose cotransporter-2 (SGLT-2) inhibitors in type 2 diabetes

Patient information A-Z


This information leaflet is for patients who have been advised to take SGLT-2 inhibitors to treat their type 2 diabetes and/or to protect their kidneys and heart. It provides information on the different medication, possible side effects and when you should stop taking the medication.

What are SGLT-2 inhibitors?

SGLT-2 inhibitors ('SGLT-2i', also known as ‘gliflozins’) are a class of drugs used in the treatment of diabetes, heart failure and chronic kidney disease. The drugs include dapagliflozin (Forxiga®), empagliflozin (Jardiance®), canagliflozin (Invokana®) and ertugliflozin (Steglatro®).

These medicines were originally developed to lower blood glucose (sugar) levels in people with type 2 diabetes. They lower blood glucose by increasing the amount of glucose passed out of the body in the urine.

These medicines have now been shown to have added benefits that include protecting the kidneys and heart. They can slow the decline in kidney function and reduce the risk of heart failure and heart attacks in individuals at most risk. These kidney and heart benefits apply to all individuals, not just those with diabetes.

If you are prescribed an SGLT-2i and have other medical problems, you might be asked to have extra blood pressure measurements taken. The doctor prescribing the SGLT-2i will advise if this is necessary for you.

Possible side effects of SGLT-2 inhibitors

Common (may affect 1 in 10 people but is common in 1 in 100)

  • Hypoglycaemia (low blood sugar) – the risk of low blood sugar is higher if you take an SGLT-2i with other medicines such as gliclazide, glimepiride, glibenclamide or insulin to treat your diabetes.You may need to reduce your other medications. Your doctor will advise you.
  • Dehydration – this can be a result of the SGLT-2i increasing your urine output. You might notice that you are dizzy and/or thirsty. If you are on water tablets (diuretics), your doctor may advise reducing your dose of the diuretic.
  • Fungal genital infections – Thrush – as SGLT-2i work by increasing the amount of glucose in your urine, this increases the risk of vaginal or penile thrush. Most cases are mild and can be treated with over-the-counter medicines. Personal hygiene is important in helping you lower your risk of developing thrush.
  • Urinary tract infections – water infection – seek medical attention if you have symptoms of a water infection, for example burning sensation when passing urine, fever and/or your urine contains blood or appears cloudy.

Uncommon (1 in 1000 people)

  • Diabetic ketoacidosis (DKA)
    DKA is an increase in acid in the blood, from ketones (chemicals that the body creates when it breaks down fat to use for energy). DKA is a rare but serious condition, which requires urgent medical treatment. It can happen with a normal blood sugar level.

    Symptoms and signs of DKA include nausea, vomiting, abdominal (stomach) pain, rapid breathing and dehydration. It can also cause drowsiness and confusion. It can cause a sweet smell on the breath, and/or a sweet or metallic taste in the mouth, which is sometimes described as similar to pear drops or nail varnish remover.

    If you experience any of these symptoms or signs, even if your blood glucose levels are normal, you should seek urgent medical advice, telling them you are taking an SGLT-2i.

    The risk of DKA is increased with:
    – prolonged fasting
    – very low carbohydrate diets (also called ketogenic diets), you should seek medical advice before starting any low carb diets
    – excessive alcohol consumption
    – dehydration
    – sudden reductions in insulin dose
    – a higher need of insulin due to major surgery
    – any illness including infections such as chest infection, flu, winter vomiting bug and COVID-19
  • Necrotising fasciitis of the perineum or Fournier’s gangrene
    This is a rare but serious or even potentially life-threatening infection of the genitals and the area around the anus. If you develop pain, swelling, redness of the genital region and feel unwell with fever, you should seek medical advice urgently.

Non-urgent advice: When should I stop taking my SGLT-2 inhibitor (gliflozin)?

SGLT-2i should be temporarily stopped if you become unwell

To keep safe whilst using SGLT-2i, we recommend following some simple instructions called 'Sick Day Rules' if you become unwell, particularly with vomiting, diarrhoea and fever.

Sick Day Rules

  • You should temporarily stop these medications, if unwell, especially if you are experiencing vomiting, diarrhoea or fever.
  • Stay hydrated and keep drinking fluids (try taking regular small sips).
  • Do not fast (starve). Maintain carbohydrate intake (starchy food).
  • Seek medical advice if you cannot keep fluids down or if you have been told to limit the amount of fluid you can drink (particularly for heart failure patients).
  • Seek urgent medical attention as above so that DKA can be excluded as the cause.
  • Tell the doctor you are taking an SGLT-2 inhibitor (gliflozin), so they can ensure you have the correct tests, in particular, excluding DKA.

SGLT-2i should be temporarily stopped if you are told to fast (starve)

You should stop taking SGLT-2i at least one day before fasting for surgery or a procedure. SGLT-2i can be restarted once you are stable post-surgery and you are eating and drinking normally.

Foot care

It is important to check your feet regularly. If you have an active infection in the foot, and/or are likely to require surgery on your foot, your diabetes team may recommend that you should temporarily stop these medications.

Pregnancy and breastfeeding

Do not use these tablets if you are:

  • pregnant
  • breastfeeding
  • sexually active but not using contraception (and so could potentially become pregnant)

Please read the patient information leaflet that comes with the tablets for further information.

We are smoke-free

Smoking is not allowed anywhere on the hospital campus. For advice and support in quitting, contact your GP or the free NHS stop smoking helpline on 0800 169 0 169.

Other formats

Help accessing this information in other formats is available. To find out more about the services we provide, please visit our patient information help page (see link below) or telephone 01223 256998.

Contact us

Cambridge University Hospitals
NHS Foundation Trust
Hills Road, Cambridge

Telephone +44 (0)1223 245151