What are Sulphonylureas?

What are Sulphonylureas?

Sulphonylureas are a class of medications that are commonly used to treat type 2 diabetes. They can be particularly helpful in people who have diabetes due to a problem with their genes (sometimes called monogenic diabetes) or have diabetes due to steroid medication.

There are a number of different tablets in the sulphonylurea family, these include:

Generic nameBrand or Trade name
GliclazideDiamicron, Diamicron MR (modified release)
GlipizideGlibenese, Minodiab

How do Sulphonylureas work?

Sulphonylureas work by causing your body to produce more insulin. Insulin is the hormone that is produced by the pancreas which helps your body to use glucose from the carbohydrates in the food you eat for energy. By producing more insulin, your blood glucose levels will fall.

Sulphonylureas reduce the symptoms of high blood glucose levels (such as passing large amounts of urine and feeling thirsty). In the long-term, good control of blood glucose levels reduces the risk of developing problems with your eyes, kidneys and feet.

How are Sulphonylureas taken?

It is taken as a tablet once or twice per day either just before or shortly before eating. The dose you are prescribed may be altered by your doctor or nurse depending on your blood glucose levels.

Sulphonylureas and Hypoglycaemia

Sulphonylureas can cause hypoglycaemia (which is a low blood glucose level, less than 4mmol/L). If you have a hypo, you may feel sweaty, shaky and/or hungry. Some people also get a pounding heart (palpitations) and if untreated you can become confused and lose consciousness.

If you have a hypo you should treat this by eating some fast-acting carbohydrate (such as 4 jelly babies or 5 dextrose tablets, 125 ml cola or 200 ml fruit juice).

Hypoglycaemia is more common in people taking sulphonylureas when they miss a meal, exercise strenuously or drink alcohol.

If you are having frequent episodes it is important to let your doctor or nurse know, as your dose may need to be changed.

Other side effects of Sulphonylureas

Most people can take sulphonylureas without experiencing many other side effects. However, some people may experience:

  • Nausea
  • Diarrhoea
  • Constipation
  • Weight gain

Rarer side effects caused by sulphonylureas can include damage to the liver, which causes yellowing of the skin, or low numbers of blood cells making you more likely to bleed or get infections. It is important that if you experience any of these rare side affects you contact your doctor or nurse.

Sulphonylureas and Driving

Group 1 License (cars and motorcycles)

If you are a Group 1 licence holder you do not need to inform the DVLA if you are prescribed any sulphonylureas. However, you should follow the “5 to drive” policy and make sure your blood glucose levels are over 5 mmol/L.

If you feel hypo whilst driving you must pull the car over as soon as you can safely do so, move to the passenger side of the car and follow your usual hypo treatment. You must wait 45 minutes after treating a hypo before driving again.

It is not essential for Group 1 licence holders to monitor blood glucose before driving, but it is considered good practice to do so. You must monitor your blood glucose regularly if you do not have good warning symptoms of hypoglycaemia.

Group 1 License (lorries and buses)

If you hold a Group 2 licence you must tell the DVLA if you are prescribed any sulphonylureas. You must test your blood glucose levels every 2 hours during periods of driving and must not drive if your blood glucose is less than 5 mmol/L.

Even though you feel back to normal, you must not drive for 45 minutes after you have treated the hypo and returned your blood glucose levels above 5 mmol/L. This is very important because your concentration and speed of reaction are not as good in the immediate period after a hypo. You will have your licence regularly reviewed by the DVLA.

If you are in any doubt about driving whilst taking sulphonylureas, then speak to your diabetes care team or have a look at the national guidelines about driving when you have diabetes.

Who should not take Sulphonylureas?

Sulphonylureas are usually prescribed to adults over 18 years that have type 2 diabetes. They may not be suitable for some people. You should tell your doctor before starting any sulphonylureas if you:

  • Have had an allergic reaction to any medications in the past
  • Have tested positive for ketones
  • Have severe kidney or liver disease
  • Are pregnant or breastfeeding
  • Need to have surgery
  • Have type 1 diabetes
  • Are taking an anti-fungal medication called Miconazole
  • Have a rare condition called Porphyria

What if I forget to take it?

If you miss a dose of your medication, then take the next dose at the usual time. Do not take a double dose to make up for a forgotten dose.

What if I take too much?

Taking an overdose of sulphonylureas can cause low blood glucose levels. If you think your blood glucose levels are low then have some quick-acting carbohydrate that will get sugar into your bloodstream, such as full-sugar fizzy drinks, orange juice or jelly babies.

As this type of food will not last a long time in your blood, you may also need to eat a starchy carbohydrate such as a sandwich or biscuit.

Getting the most from your treatment

Continue to take your medication regularly unless your doctor or nurse tells you otherwise. It is important that you keep your regular clinic appointments. If you have been advised by your doctor about changes to your diet, stopping smoking or taking regular exercise, it is important that you follow this advice.

If you have any questions or concerns about your medication then please speak to your doctor or nurse.

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