An older sulfonylurea
Tolbutamide
An older, short-acting sulfonylurea taken with meals to lower blood sugar in type 2 diabetes, carrying a risk of hypoglycaemia.
What is Tolbutamide?
Tolbutamide is an older, short-acting sulfonylurea used to lower blood sugar in type 2 diabetes. It prompts the pancreas to release more insulin, so it can cause low blood sugar (hypoglycaemia) and is taken with meals to reduce that risk. Newer agents are usually preferred, as tolbutamide can cause weight gain and offers no proven organ protection.
Education and reference only. This is a plain-language guide to Tolbutamide — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Tolbutamide is one of the oldest sulfonylureas, a class of tablets used to lower blood sugar in type 2 diabetes. It is short-acting compared with some other sulfonylureas, and is taken with meals. While newer diabetes medicines are now generally preferred, tolbutamide is still encountered and works by squeezing more insulin out of the pancreas. Because it raises insulin regardless of food, the main thing to understand is its risk of low blood sugar.
How it works
Tolbutamide stimulates the beta cells of the pancreas to release more insulin. The extra insulin moves glucose out of the blood and into the body's cells, lowering blood sugar. Because it pushes insulin release whether or not you have eaten, blood sugar can fall too low (hypoglycaemia) if a meal is missed or delayed — which is why it is taken with food. Its short action means the effect of each dose does not last as long as some other sulfonylureas.
Company & origin
Originated / developed by: Available as a generic medicine..
One of the first sulfonylureas, in use since the 1950s.
What it treats
Conditions Tolbutamide is used for
Practical use
How to take Tolbutamide
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Take it with meals, and do not skip meals while using it.
- Carry a fast-acting sugary snack or drink in case of low blood sugar.
- Learn to recognise and treat a 'hypo' (shakiness, sweating, hunger, confusion).
- Take care with alcohol, which can make blood sugar harder to predict.
- If a meal is going to be missed, ask your prescriber how to handle that dose.
Weighing it up
Advantages & disadvantages of Tolbutamide
Advantages
- Effective at lowering blood sugar in type 2 diabetes.
- Short-acting, which can mean a lower risk of prolonged low blood sugar than longer-acting sulfonylureas.
- Long-established and inexpensive as a generic medicine.
Disadvantages
- Can cause low blood sugar (hypoglycaemia), especially if meals are missed.
- Tends to cause weight gain.
- An older agent with no proven heart or kidney protection, so newer medicines are often preferred.
Practical use
Good to know
The key thing with tolbutamide is the risk of hypoglycaemia (low blood sugar), so it is taken with meals and you should not skip meals while on it. Learn the warning signs of a 'hypo' — shakiness, sweating, hunger, confusion — and how to treat it with a sugary drink or snack. It can cause weight gain, and unlike some newer diabetes medicines it has no proven heart or kidney protection. Alcohol and other medicines can affect blood sugar, so flag changes to your prescriber.
Who should not take it / use with caution
- People with type 1 diabetes or diabetic ketoacidosis.
- People with severe liver or kidney problems, where the risk of low blood sugar rises.
- Anyone allergic to tolbutamide or related sulfonylureas; used with caution in pregnancy, breastfeeding and in frail or older people prone to hypos.
Monitoring
- Blood sugar (glucose) levels and longer-term control (HbA1c)
- Weight, and any pattern of low blood-sugar episodes
- Kidney and liver function, particularly in older people
Side effects
- Low blood sugar (hypoglycaemia) — shakiness, sweating, hunger, confusion — particularly if a meal is missed.
- Weight gain.
- Digestive upset, and less commonly a skin rash or, rarely, effects on blood counts or the liver.
Key interactions
- Other blood-sugar-lowering medicines, including insulin, which add to the risk of hypos.
- Alcohol, which can both lower blood sugar and cause flushing with some sulfonylureas.
- Many medicines (including some antibiotics, antifungals and others) can raise or lower its effect, so check before adding new ones.
Available as: Tablets.
Answers
Tolbutamide: frequently asked questions
Why must I take tolbutamide with meals?
Tolbutamide makes the pancreas release more insulin whether or not you have eaten, so taking it with meals helps match that insulin to incoming food and reduces the risk of your blood sugar dropping too low. Skipping meals while on it can trigger a 'hypo'.
What is a 'hypo' and how do I treat it?
A 'hypo' is hypoglycaemia — blood sugar falling too low — causing shakiness, sweating, hunger or confusion. Treat it promptly with a fast-acting sugary drink or snack, then a longer-acting carbohydrate. Learn to recognise the signs and tell your diabetes team if hypos happen.
Will tolbutamide make me put on weight?
Weight gain is a recognised effect of sulfonylureas like tolbutamide. If weight is a concern, discuss it with your prescriber, as some newer diabetes medicines are weight-neutral or can help with weight, which is one reason they are often preferred now.
Is tolbutamide still used?
It is an older medicine, and newer diabetes treatments are usually preferred because they carry less risk of low blood sugar, may help with weight, and some protect the heart and kidneys. Tolbutamide is still effective at lowering blood sugar but offers no proven organ protection.
Can I drink alcohol on it?
Be cautious. Alcohol can make blood sugar harder to predict and may increase the risk of low blood sugar, and with some sulfonylureas can cause flushing. If you do drink, do so in moderation and with food, and discuss it with your diabetes team.
The wider class
About Sulfonylureas
Tolbutamide belongs to the sulfonylureas class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
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Authoritative sources
- BNF: Tolbutamide.
- NICE CKS: Type 2 diabetes.
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