Drinks for Prediabetes: What to Look For in UK Supermarkets

Sugary drinks

Regular fizzy drinks, sweetened squash, milkshakes, sweetened iced teas and many energy drinks can pack in a surprising amount of sugar without making you feel especially full. A regular 330ml can of cola typically contains around 35g of sugar — already more than the daily guideline for an adult, from one drink.

That's why one of the easiest supermarket swaps is changing a regular sugary drink for water or sparkling water, a sugar-free or diet version, no-added-sugar squash, or unsweetened tea or coffee.

None of this means you can never have a sugary drink. It just means that if it's something you buy every week, the drinks aisle is often one of the simplest places to cut back on sugar without changing anything else about your meals.

What about zero-sugar and diet drinks?

Comparing a sugar-sweetened fizzy drink with its zero-sugar version, the zero-sugar one removes a genuinely large amount of sugar. Approved sweeteners used in the UK go through safety assessment before they're allowed in food and drink, so there's a solid basis for using them to cut sugar.

That said, a zero-sugar drink isn't automatically “healthy” in every sense — it can still be acidic or caffeinated, and acidic fizzy drinks can affect teeth whether they contain sugar or sweeteners.

But if the realistic choice in front of you is regular cola versus zero-sugar cola, that's a perfectly reasonable way to bring down the sugar in your regular shop. PrediabetesBasket is interested in swaps like that — not in pretending everyone's about to switch to drinking nothing but tap water.

Fruit juice is different from whole fruit

This one catches plenty of people out. A carton saying “100% orange juice” sounds a world away from a fizzy drink, and nutritionally it is different — juice provides vitamins and minerals that a can of cola doesn't.

But that doesn't mean the sugar can be ignored. Once fruit is juiced or blended, its sugars behave differently in the body than sugar still locked inside whole fruit. Whole fruit keeps its fibre and structure; juice and smoothies make it very easy to get through the sugar from several pieces of fruit in one go.

Current UK guidance is to keep fruit juice, vegetable juice and smoothies combined to about 150ml a day — a small glass, not a large tumbler. And however many fruits go into that juice or smoothie, 150ml only ever counts as a maximum of one of your five-a-day.

So the useful question isn't “is fruit juice allowed?” — it's “how much am I actually pouring?” A 150ml glass and a 400ml café smoothie are very different things.

Smoothies deserve the same portion check

Smoothies can feel virtuous because the label lists strawberries, banana, mango, spinach and half a dozen other ingredients. But shop-bought smoothies can still carry a fair amount of carbohydrate and sugar, and because the fruit's already been blended, it's easy to get through more of it, more quickly, than if you sat down and ate the equivalent whole fruit.

That's another reason to check the bottle size alongside the nutrition panel. If the label says 9g of sugars per 100ml and the bottle holds 300ml, the whole bottle comes to 27g of sugar. The per-100ml figure lets you compare drinks fairly; the bottle size tells you what you're actually drinking. You need both.

Use the per-100ml column to compare drinks

This is probably the quickest trick in the whole article. Two bottles can have very different serving sizes, so comparing numbers “per serving” can be misleading — always start with the figure per 100ml.

UK front-of-pack labelling uses these sugar bands for drinks:

(There are extra rules for larger servings too, so a big bottle can tip into “high” through sheer quantity even if the per-100ml figure looks moderate.)

The traffic-light colour is handy for quick comparisons, but then look at the actual container. A 500ml bottle contains five times whatever's listed per 100ml — so a drink with 8g of sugars per 100ml works out to 40g in a 500ml bottle. That one calculation often tells you more than anything on the front of the pack.

“No added sugar” doesn't mean “sugar-free”

This is one of the most useful label distinctions to get your head around. “No added sugars” is a regulated claim in Great Britain — broadly, it means no sugar or other sweetening ingredient has been added during manufacture. But the product can still contain sugars that occur naturally in its ingredients.

“Sugar-free”, by contrast, is a stricter claim: the product must contain no more than 0.5g of sugars per 100g or 100ml, full stop.

So a juice, a milk-based drink or a plant drink can genuinely say “no added sugar” while still containing meaningful natural sugar — nobody's tipped table sugar into the mix, but the sugar's there regardless. The nutrition panel is still worth a glance. Our guide to reading food labels goes through the rest of the panel in more detail.

What about ordinary milk?

Milk is a good example of why chasing the lowest sugar number can be misleading. Plain cow's milk contains lactose, a naturally occurring milk sugar, so you'll see carbohydrate and sugars on the label even though nothing's been added. Milk also brings useful protein and calcium to the table, so seeing “sugar” on a bottle of plain milk doesn't put it in the same category as a bottle of cola.

Flavoured milks and milkshakes are a different story, since some contain a fair amount of added sugar — worth checking the panel rather than assuming all milk-based drinks are alike.

Plant-based drinks vary enormously

Oat, soya, almond, coconut and other plant-based drinks are everywhere now, but they're not interchangeable nutritionally. Independent comparisons show real differences in carbohydrate, sugar and especially protein between different types and brands, and fortification with things like calcium, iodine, B12 and vitamin D varies too. Oat-based drinks, for instance, tend to carry more carbohydrate than many unsweetened almond or soya drinks — that doesn't make oat milk “bad”, it just means “plant-based” alone tells you very little.

Worth comparing: is it sweetened or unsweetened, carbohydrate and sugars per 100ml, protein content, and how much you actually use day to day. Choosing the unsweetened version of whichever plant milk you like is generally the simplest swap here.

Tea and coffee: sometimes the extras are the real drink

Plain tea and coffee contain very little sugar unless you add it yourself. The picture changes once you move into bottled coffees, flavoured lattes, syrups, frappes, bubble teas and sweetened chai drinks, some of which can carry a surprising amount of added sugar.

So rather than worrying about an ordinary cup of tea, it's worth comparing like with like — an unsweetened iced coffee against a caramel-flavoured bottled one with added sugar, say, rather than treating “coffee” as one single category.

What about energy drinks?

Energy drinks are really two separate questions: sugar and caffeine. Some regular versions contain plenty of both. Zero-sugar versions remove or cut the sugar, but can still carry a similar amount of caffeine.

Under UK rules, drinks with more than 150mg of caffeine per litre have to carry a high-caffeine warning and state the caffeine content on the label. For most healthy adults, total caffeine intake of up to around 400mg a day is considered unlikely to cause problems, though this varies by person, and the recommended maximum in pregnancy is lower, at around 200mg a day.

So a zero-sugar energy drink might sort out the sugar side of things without touching the caffeine side — worth checking both.

Look beyond front-of-pack claims

Packaging is designed to catch your eye — “zero sugar”, “no added sugar”, “natural”, “vitamin enriched”, “high protein”, “plant based”, “100% fruit”, “electrolytes”. Some of these have specific legal meanings; others tell you only one small thing about the product. None of them replaces the nutrition panel.

A simple routine covers most supermarket drinks:

1. Check sugars and carbohydrate per 100ml.
2. Look at the bottle or serving size.
3. Check whether sugar's been added, or whether it's naturally there.
4. Consider what else the drink offers — protein, calcium, caffeine.
5. Compare it with similar drinks, not completely different ones.

A quick example

Take three imaginary drinks:

The regular fizzy drink comes to about 35g of sugar in a 330ml can. The zero-sugar version removes that sugar entirely. The juice still contains sugar even without anything added during manufacture, which is why keeping it to around 150ml a day makes sense.

None of these drinks is morally better or worse than the others — they just call for different questions.

Look at the overall pattern

This matters. Someone's shop could be full of vegetables, wholegrains, beans, fish, nuts, plain yoghurt and all sorts of other good things — plus one bottle of lemonade. That lemonade shouldn't turn into a judgement on the whole week.

The point of traffic-light-style feedback is to help patterns stand out, not individual purchases. Buying three big bottles of cola every week is a different pattern to buying one small bottle occasionally, and worth treating differently. PrediabetesBasket looks at the whole basket — what's already going well, alongside anything worth a second look. Food and drink choices are information, not a report card.

A simple rule for the drinks aisle

• Sugary soft drink? See if a lower-sugar or sugar-free version would suit you.
• Juice or smoothie? Think about that 150ml guideline and check the actual portion.
• Milk? Remember lactose shows up as “sugar” on the label even though nothing's added.
• Plant-based milk? Look for unsweetened, and compare carbs, protein and fortification.
• “No added sugar”? Remember it can still contain natural sugar.
• Energy drink? Check sugar and caffeine separately.

And for almost everything: check per 100ml first, then think about how much you'll actually drink.

You don't need to find a perfect drink. A handful of sensible changes to the things you buy regularly will do far more than worrying over one bottle in an otherwise balanced shop. If you're doing the same sort of comparison elsewhere in the trolley, our supermarket snacks guide takes the same approach.