No single food causes diabetes, but certain eating patterns sustained over years can significantly raise your risk of developing type 2 diabetes. The foods most strongly linked to increased risk are sugary drinks, processed meats, refined grains, and ultra-processed packaged foods. These work through overlapping mechanisms: they spike blood sugar repeatedly, promote fat accumulation in the liver, and drive weight gain, all of which gradually erode your body’s ability to manage insulin.
It’s worth noting upfront that type 1 diabetes is a completely different disease. It’s caused by an autoimmune reaction where the body destroys its own insulin-producing cells. Diet plays no role in causing it. When people ask “what food causes diabetes,” they’re almost always talking about type 2, which accounts for roughly 90 to 95 percent of all cases.
Sugar-Sweetened Beverages Carry the Strongest Link
If any single food item comes closest to “causing” diabetes, it’s sugary drinks. People who consume one to two cans of soda or sweetened beverages per day have a 26% greater risk of developing type 2 diabetes compared to people who rarely drink them. A large study tracking over 192,000 people for more than two decades found that increasing sugary beverage intake by just 4 ounces per day over a four-year period was associated with a 16% higher risk of type 2 diabetes in the following four years.
The problem with liquid sugar is speed. When you drink a soda or sweetened iced tea, the sugar (often a mix of glucose and fructose) hits your bloodstream fast because there’s no fiber or protein to slow digestion. Your pancreas responds by flooding your system with insulin. Do this daily for years, and your cells start responding less and less to insulin, a condition called insulin resistance.
Fructose, which makes up about half the sugar in most sweetened drinks, is especially problematic for the liver. Unlike glucose, which your muscles and brain readily use, fructose is processed almost entirely by the liver. High fructose intake stimulates the liver to produce new fat, impairs its ability to burn existing fat, and triggers inflammation. This cascade leads to fatty liver disease, which in turn worsens insulin resistance throughout the body. Even when total calorie intake is the same, fructose produces worse metabolic outcomes than an equal amount of glucose.
Refined Carbohydrates and Blood Sugar Spikes
White bread, white rice, pastries, and most breakfast cereals are refined grains, meaning the fiber-rich outer layers have been stripped away during processing. What’s left digests quickly and has a high glycemic index, a measure of how fast a food raises blood sugar. Non-starchy vegetables, legumes, whole fruits, and intact whole grains, by contrast, tend to have a moderate or low glycemic index.
Among all the things that influence insulin secretion, dietary carbohydrate has the most potent effect, and the type of carbohydrate matters enormously. High-glycemic foods trigger a sharp insulin spike after eating. Over time, this pattern promotes fat storage, increases hunger, and may slow your metabolic rate. Animal studies show a clear progression: a high-glycemic diet first produces elevated insulin levels, then increased fat cell size, then greater overall body fat, then lower energy expenditure, and finally increased hunger. It becomes a self-reinforcing cycle.
One compelling piece of genetic research found that higher insulin secretion strongly predicted higher body mass index, but not the reverse. In other words, the insulin spikes appear to drive weight gain rather than weight gain driving the insulin problem. This doesn’t mean eating a slice of white bread will give you diabetes, but a diet built around refined carbohydrates creates the metabolic conditions that move you in that direction.
Processed Meat and Diabetes Risk
Hot dogs, bacon, sausage, deli meats, and other processed meats are consistently linked to higher type 2 diabetes risk in large population studies. The connection isn’t just about the fat content. Processed meats contain preservatives like nitrates and nitrites, high levels of sodium, compounds formed during high-heat cooking, and heme iron, all of which can affect the body in ways that promote insulin resistance.
These compounds contribute to oxidative stress (a type of cellular damage), chronic low-grade inflammation, and direct toxic effects on pancreatic cells that produce insulin. Interestingly, when researchers looked at which specific component explained the most risk, sodium had a stronger statistical link than saturated fat, cholesterol, or heme iron. This suggests the preserving and processing itself, not just the meat, is a key part of the problem.
Ultra-Processed Foods as a Category
Beyond individual ingredients, the overall level of food processing matters. Ultra-processed foods include things like packaged snacks, frozen meals, instant noodles, candy, flavored yogurts, and fast food. A large analysis published in Diabetes Care, drawing on data from three major U.S. studies covering over 5 million person-years of follow-up, found that people in the highest category of ultra-processed food consumption had a 46% higher risk of type 2 diabetes compared to those who ate the least. Each additional daily serving of ultra-processed food was associated with a 5% increase in risk.
A broader meta-analysis combining multiple studies found that every 10% increase in ultra-processed food as a share of someone’s diet was linked to a 12% higher risk of type 2 diabetes. These foods tend to combine refined carbohydrates, added sugars, unhealthy fats, sodium, and artificial additives in ways that are easy to overeat. They’re engineered for palatability and convenience, which makes portion control difficult.
What About Artificial Sweeteners?
Many people switch to diet sodas or sugar-free products assuming they’re a safe alternative. The picture is more complicated than that. Research from the Weizmann Institute of Science found that artificial sweeteners, despite having no calories, can alter the composition of gut bacteria in ways that raise blood sugar levels. In mouse studies, animals fed artificial sweeteners developed glucose intolerance, and transferring their gut bacteria to other mice reproduced the same metabolic problems.
In humans, data from 381 non-diabetic individuals showed that long-term consumption of artificial sweeteners was associated with increased weight and higher fasting blood glucose levels. Even short-term consumption produced changes in blood sugar control and shifts in gut bacteria composition. This doesn’t mean artificial sweeteners are definitively worse than sugar, but the assumption that they’re metabolically neutral appears to be wrong for many people.
Foods That Lower Your Risk
The flip side of this question matters just as much. Fiber is one of the most protective dietary factors against type 2 diabetes. It slows the absorption of sugar into the bloodstream, feeds beneficial gut bacteria, and helps you feel full on fewer calories. The Dietary Guidelines for Americans recommend 22 to 34 grams of fiber per day depending on age and sex, but most Americans fall well short of that. Good sources include beans, lentils, whole oats, vegetables, nuts, and seeds.
Whole fruit deserves a special mention because it’s often unfairly lumped in with sugary foods. Large studies of postmenopausal women found no association between whole fruit intake and diabetes risk, even at the highest levels of consumption. Moderate amounts of 100% fruit juice (up to about 8 ounces per day) also showed no significant link to increased diabetes risk. The fiber, water content, and micronutrients in whole fruit slow sugar absorption enough to avoid the metabolic problems caused by the same amount of sugar in a soda.
Physical activity plays a major role alongside diet. Being active fewer than three times per week is an independent risk factor for type 2 diabetes. Combining regular movement with a diet built around whole, minimally processed foods is the most effective way to reduce risk. Even modest weight loss of 5 to 7% of body weight can substantially lower the chances of progressing from prediabetes to full type 2 diabetes.
Why It’s About Patterns, Not Single Foods
The honest answer to “what food causes diabetes” is that no single food does. Type 2 diabetes develops over years as the result of sustained metabolic stress from a combination of diet, activity levels, genetics, and body composition. Having overweight or obesity is the strongest modifiable risk factor. Being 45 or older, having a family history, or belonging to certain racial and ethnic groups (African American, Hispanic/Latino, American Indian, Alaska Native, and some Pacific Islander and Asian American populations) also increases risk independently of diet.
What diet does is create the conditions that accelerate or slow the process. A pattern heavy in sugary drinks, refined grains, processed meats, and ultra-processed packaged foods pushes the body toward insulin resistance, liver fat accumulation, and chronic inflammation. A pattern centered on vegetables, legumes, whole grains, nuts, and whole fruits works against those same processes. The most impactful single change most people can make is eliminating daily sugary beverages, since the evidence linking them to diabetes risk is among the strongest for any dietary factor.