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Continuing with our medication series today we are discussing the class known as sulphonylureas. As with all the posts in this series, this is not advice about whether or not you should take them. Only how they work and the pros and cons of each medication.

What are sulphonylureas?

These are class of medications mostly used in type 2 diabetes, although they can also be used successfully in certain genetic forms of diabetes. They work by stimulating the pancreas to produce more insulin. They are one of the older diabetes medications and thus have been around for some time.

There are various types and brands. The most commonly known are gilbenclamide, glimepiride, glipizide, gliclazide and tolbutamide (though this is an older version and not widely used now).

These are usually taken once or twice a day with food to help counteract the glucose rise caused by eating. Usually this will be at breakfast and your main meal.

Doses vary depending on the type of medication you take and how much you need. Your medical team can advise you on this.

When sulphonylureas will be prescribed?

If your glucose levels are above target this will be an indication to commence some form of medical therapy. Metformin usually acts as the first line medication in type 2 diabetes. However, not everyone can tolerate Metformin and therefore sulphonylureas may even be used first line.

Historically, sulphonylureas were second line but as more diabetes medications are coming to market, prescribers now have more options to better suit the patient and their other co-morbidities. Therefore, sulphonylureas are not as popular as they once were in some areas.


They help to lower glucose levels by increasing the amount of insulin released from the pancreas. The expected drop in your HbA1c may vary anywhere between 1-2% (11-22mmol/mol). Therefore, they are quite effective compared to some other type 2 diabetes medications.


As sulphonylureas make your pancreas produce more insulin they increase the risk of causing hypoglycaemic episodes (low blood sugars). This means you will likely need to test your glucoses 1-2 times per day and any other time you feel hypo symptoms.

Insulin is also an anabolic hormone. This means it encourages building up your body and increases your absorption of nutrients. Therefore, sulphonylureas can make you put on weight. The expected weight gain is around 2kg. So it is not a huge amount of weight but if you already suffer with a weight problem, this probably won’t help.

When not to use sulphonylureas

Like all medications there are some contraindications. Sulphonylureas ideally should not be used if you are frail and/or have inconsistent eating patterns. This is because this can leave these individuals very susceptible to hypos. Not all frail individuals will need to stop taking these but there are other options that may be better suited as you transition into your latter years.

Renal problems are also a contraindication for this class of medications. Insulin is cleared by the kidneys and if this function is impaired it can lead to extra insulin hanging around in your circulation leading to hypos.

Sulphonylureas are not suitable for patients where they lack the beta cell function to produce insulin. This is most common in type 1 diabetes but is also a consideration in type 3c diabetes. If you don’t know what type 3c diabetes is I have previously blogged on this here. Essentially, asking the pancreas to produce more insulin when it has no capability to do so, will not work.

Finally, some diabetes teams might suggest stopping sulphonylureas if you commence insulin therapy. Particularly if you are taking large doses. This is because the need for insulin therapy suggests the pancreas is no longer able to release enough insulin to control your glucose levels. So why continue to stress the pancreas to produce more insulin when we are already giving you additional insulin?

Need more help

If you need more support we offer a range of 1:1 consultancy services and online programmes focused on helping you improve your glucose control and health for the long term. These include our type 2 diabetes recovery programme, type 1 glucose stability programme and winning weight loss programme. Go to the pages using the links above or in the headers or get in touch if you have questions.