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Advice for people with diabetes and their families

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Does sugar cause diabetes?

Many people want to know what causes diabetes. We don’t know exactly what causes type 1 diabetes, but it isn’t linked to lifestyle, and so sugar doesn’t directly cause the condition. The question of whether sugar directly causes type 2 diabetes is a bit complicated.

So here we explain what we mean by sugar, the impact sugar can have on your risk of developing type 2 diabetes, and whether you can eat sugar when you have diabetes.

Because diabetes is a condition where blood sugar levels are too high, it’s all too easy to think eating too much sugar is the cause. But what’s the truth about sugar and how does it affect diabetes?


What is sugar?

Sugar is found naturally in fruit, vegetables (fructose) and dairy foods (lactose). It’s also added to food and drink by food manufacturers, or by ourselves at home. These types of added sugars are called ‘free sugars’ and they are also present in pure fruit juices, smoothies, syrups and honey. The debate about sugar and health is mainly around free sugars. This includes:

  • table sugar that we add to our hot drinks or breakfast cereal
  • caster sugar, used in baking
  • sugars hidden in sauces, ready meals, cakes and drinks.
  • honey and syrups, like golden syrup or agave syrup 
  • pure fruit juice 
  • smoothies. 

Does sugar cause diabetes?

There are two main types of diabetes – type 1 and type 2 diabetes.

In type 1 diabetes, the insulin producing cells in your pancreas are destroyed by your immune system. No amount of sugar in your diet – or anything in your lifestyle – has caused or can cause you to get type 1 diabetes.

With type 2 diabetes, though we know sugar doesn’t directly cause type 2 diabetes, you are more likely to get it if you are overweight. You gain weight when you take in more calories than your body needs, and sugary foods and drinks contain a lot of calories.

So you can see if too much sugar is making you put on weight, then you are increasing your risk of getting type 2 diabetes. But type 2 diabetes is complex, and sugar is unlikely to be the only reason the condition develops.

We also know that sugar sweetened drinks, like canned soft drinks, are associated with an increased risk of type 2 diabetes and this is not necessarily linked to their effect on body weight. 

Find out your risk of type 2 diabetes.

If I have diabetes, can I eat sugar?

Having diabetes doesn’t mean you have to cut sugar out of your diet completely. We all enjoy eating sugary foods occasionally, and there’s no problem including them as a treat occasionally. And, for some people with diabetes, sugary drinks or glucose tablets are essential to treat a hypo, when your blood glucose levels get too low.

However, we are eating too much free sugar and harming our health as a result. Being overweight can make it difficult to manage your diabetes and increase your risk of getting serious health problems such as heart disease and stroke in the future. Too much sugar is bad for your teeth too.

Should I stop eating sugar altogether?

You don’t have to cut sugar out of your diet completely. Sugar is found naturally in fruit, vegetables and dairy foods, and most of us in the UK are not getting the recommended five fruit and veg a day so it’s important we don’t cut these out as they are so good for you. It’s better to eat whole fruit and vegetables rather than having juices or smoothies, as even the pure fruit juices contribute to free sugar intake. If you do have juice, keep to just one small glass – 150ml – a day.

It’s the free sugar that we all need to cut down on. And it’s not just the obviously sweet things like biscuits and chocolate. It’s the hidden sugar lurking in many foods, such as baked beans, pasta sauces, tomato ketchup, yogurts and ready meals. Some drinks are packed with sugar, too.

How can I tell from a label if there are free sugars?

Food labels are the best way to work out how much sugar is in what you're eating. The figures for sugar are for total sugar and don’t tell you how much of the sugar comes from natural sugars, such as in fruit, and how much comes from free sugar. Some foods and drink don’t have the word ‘sugar’ in the ingredients list, but still have sugar added. Honey, sucrose, glucose, glucose syrup, dextrose, fructose, hydrolysed starch, corn and maize syrup are all free sugars. If you see any of these words on the ingredients list, you know sugar has been added.

How much sugar should I be eating?

We all should be cutting down our free sugar intake, and the maximum recommended daily amount is 30g for adults – which works out at just seven teaspoons a day. Given that a tablespoon of ketchup contains around one teaspoon of sugar, a chocolate biscuit has up to two, and a small serving of baked beans almost three – you can see how quickly the teaspoons tot up.

How to reduce your sugar intake

Simple changes can dramatically reduce the amount of free sugar in your diet.

  • Instead of chocolate bars, sweets, cakes and biscuits, choose healthier snacks such as unsweetened yogurts, unsalted nuts, seeds, fruits and vegetables. For example, try natural yogurt mixed in with chopped fruit or a small handful of nuts.
  • Experiment with reducing the sugar you use in recipes – most recipes will work just as well.
  • Try artificial sweetener in place of sugar.
  • If you normally have sugary drinks, choose diet fizzy drinks and no added sugar squashes instead. Or go for water with natural flavourings, like mint or sliced lemon. Sugary drinks are best used as a treatment for hypos.
  • Try to cook from scratch where possible – that way you can be sure of what's in your food. Check out our tasty, easy-to-follow and simple recipes.
  • Keep an eye on reduced-fat foods – many actually contain more sugar as food manufactures add sugar to compensate for the altered taste and texture caused by the fat being removed. Look at the whole food label to be sure.
  • To see whether a product is high in free sugar look at the ingredients list, which always starts with the biggest ingredient first. So if sugar or syrup is listed in the first few ingredients, the product you’re buying will contain a high proportion of sugar. 


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