Does Sugar Cause Diabetes? What the Research Really Shows

Evidence: Strong

“Does sugar cause diabetes?” is one of the most common questions people ask about blood sugar. The honest answer is more useful than a simple yes or no: where your sugar comes from matters a lot, and one source stands out above the rest. Here’s what the research shows, and the changes that make the biggest difference.

Does sugar cause diabetes?

Not directly, in the way the question usually implies. Type 2 diabetes develops when the body stops responding well to insulin (insulin resistance) and the pancreas can no longer keep up. Genetics, body weight, activity, sleep and overall diet all play a part.

But sugar is far from innocent. Large amounts of added sugar, especially in liquid form, add calories without making you feel full, which makes weight gain more likely. Fructose, half of table sugar and high-fructose corn syrup, is processed mainly by the liver, and a steady oversupply is linked to fat building up there, which in turn is tied to insulin resistance. That’s why researchers look so closely at the form sugar comes in.

Sugary drinks: the clearest link

A 2025 meta-analysis published in Advances in Nutrition pooled data from more than half a million people across multiple continents. It found that each additional daily 12-oz serving of sugar-sweetened beverages, such as soft drinks, sports drinks and energy drinks, was linked to about a 25% higher risk of type 2 diabetes. The increase started with the very first daily serving; the researchers found no amount that appeared safe.

Older research points the same way. A 2015 analysis in the BMJ found each daily serving of a sugary drink was linked to an 18% higher risk, and the link held even after accounting for body weight, which suggests drinks may raise risk through more than just added pounds. An earlier analysis in Diabetes Care found that people who had one to two sugary drinks a day had a 26% higher risk than those who rarely had any.

Why are drinks worse than food? Liquid sugar is absorbed quickly, comes with no fiber or protein to slow it down, and doesn’t register as “food” the way a meal does, so people rarely eat less to make up for it. A single 12-oz can of regular soda contains roughly 8 to 9 teaspoons of added sugar.

What about fruit juice?

The same 2025 analysis found that each daily 8-oz serving of fruit juice, including 100% juice, was linked to about a 5% higher risk. That’s a much smaller increase than soda, but it means juice isn’t the healthy swap it’s often marketed as. Whole fruit is a better choice: it delivers the same natural sugar packaged with fiber and water, which slows absorption and makes you feel full.

What about sugar in food?

Here’s the surprising part. In the 2025 analysis, sugar eaten as part of nutrient-dense whole foods, such as fruit and dairy, wasn’t linked to higher diabetes risk the way sugary drinks were. That doesn’t make cookies and candy a health food, since those are usually eaten in larger amounts and come with refined starch and fat. But it does mean you don’t need to fear an apple or a glass of milk.

The most practical takeaway: focus on added sugars, the ones put in during processing or at the table, and especially on added sugars you drink.

How much added sugar is too much?

Official advice has become stricter. The Dietary Guidelines for Americans, 2025–2030 now say no amount of added sugar is considered part of a healthy diet, and that no single meal should contain more than 10 grams of added sugar, about 2½ teaspoons. The American Heart Association recommends no more than 6 teaspoons (25 g) a day for most women and 9 teaspoons (36 g) a day for most men.

For comparison, the average American adult eats about 17 teaspoons of added sugar a day, and almost half of it comes from sugary drinks.

Where added sugar hides

Sugar shows up in plenty of foods that don’t taste like dessert. Common sources include:

• Flavored yogurt and “fruit on the bottom” cups
• Granola, cereal and breakfast bars
• Coffee-shop drinks, sweetened teas and bottled smoothies
• Pasta sauce, ketchup, barbecue sauce and salad dressings
• Bread, crackers and other packaged snacks
• Protein bars and “healthy” snack bites

To spot it, check the Added Sugars line on the Nutrition Facts label, and scan the ingredient list for words that include “sugar” or “syrup” or end in “-ose” (like dextrose or maltose). Our guide to reading a food label in 60 seconds walks you through it.

Easy swaps that cut the most sugar

Instead of…	Try…	Why it helps
A 12-oz regular soda	Sparkling water with a squeeze of lime or a splash of juice	Cuts about 8–9 teaspoons of added sugar per can
A glass of fruit juice	The whole fruit	Same sweetness, plus fiber that slows how fast sugar hits your blood
Sweetened coffee-shop drinks	Coffee or latte with milk; add cinnamon or one pump of syrup instead of three	Flavored drinks can carry more sugar than a soda
Flavored yogurt	Plain yogurt with berries	You control the sweetness; fruit sugars aren’t “added” sugars
Sweetened cereal or granola	Oats or unsweetened cereal with fruit and nuts	Breakfast is one of the easiest places to cut hidden sugar
Sports or energy drinks	Water (and electrolytes without sugar if you’re sweating heavily)	Most people don’t need the sugar these drinks contain

Start with drinks. For most people, that one change removes more added sugar than anything else, with the least effort.

What about diet soda and artificial sweeteners?

The evidence here is genuinely mixed. Some large studies link artificially sweetened drinks to a higher risk of type 2 diabetes, but researchers caution that part of this may be reverse causation: people who are already gaining weight or at higher risk often switch to diet drinks, which can make the drinks look worse than they are. Other analyses have found that replacing sugary drinks with diet versions is associated with a slightly lower risk.

The bottom line: diet soda is probably better than regular soda, but it isn’t a health drink. The 2025–2030 Dietary Guidelines also advise limiting non-nutritive sweeteners. Water, sparkling water, and unsweetened tea or coffee are the safest everyday choices.

If you already have prediabetes or diabetes

Cutting sugary drinks and added sugar is one of the simplest steps you can take, and it fits every major eating pattern the American Diabetes Association recommends, including Mediterranean and lower-carb approaches. If you take insulin or other glucose-lowering medication, talk to your doctor before making big changes to what you eat, as your doses may need adjusting.

The bottom line

Sugar’s link to type 2 diabetes is real, but it isn’t evenly spread. The strongest, most consistent evidence points at sugar you drink. If you make just one change, swap sodas, sweetened coffee drinks and juice for water or unsweetened options. Then work on the added sugar hiding in packaged foods, and stop worrying about the natural sugar in whole fruit.

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This article is for general education and isn’t medical advice. See our medical disclaimer.

Sources

1. Della Corte K, et al. Dietary Sugar Intake and Incident Type 2 Diabetes Risk: A Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies. Adv Nutr. 2025;16(5):100413. PubMed.
2. Imamura F, et al. Consumption of sugar sweetened beverages, artificially sweetened beverages, and fruit juice and incidence of type 2 diabetes. BMJ. 2015. PubMed.
3. Malik VS, et al. Sugar-sweetened beverages and risk of metabolic syndrome and type 2 diabetes: a meta-analysis. Diabetes Care. 2010. PubMed.
4. Drouin-Chartier JP, et al. Changes in Consumption of Sugary Beverages and Artificially Sweetened Beverages and Subsequent Risk of Type 2 Diabetes. Diabetes Care. 2019. PubMed.
5. U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2025–2030. PDF.
6. American Heart Association. How Too Much Added Sugar Affects Your Health. PDF.
7. American Diabetes Association. Standards of Care in Diabetes—2026. diabetes.org.
8. U.S. Food and Drug Administration. Added Sugars on the Nutrition Facts Label. FDA.