The snack that moved blood sugar most wasn't the sweet one: in 785 adults wearing glucose sensors, bread and buns topped the list, and a brisk hour afterwards pulled it back down

Most advice about blood sugar is built around meals. Snacks get less attention, even though many people eat two or three a day, and they're often eaten on the go, at odd hours, with little thought. A team at the Saw Swee Hock School of Public Health, National University of Singapore, set out to watch what snacks do to blood sugar in real life rather than in a laboratory. Their study was published online in the American Journal of Clinical Nutrition on 7 October 2026.

They followed 785 men and women aged 21 to 69, none with diabetes, for nine days of normal life. Each wore a continuous glucose monitor, a small sensor on the skin that reads glucose every few minutes, and an accelerometer that recorded movement and sleep. Six times a day their phones asked short questions about what they had just eaten or drunk. That produced 3,325 snacking episodes. For each one the researchers measured how far glucose rose above its starting level over the next two hours, a figure called the incremental area under the curve, which averaged 63.8 mmol/l·min. Because every person contributed several snacks, the main comparisons were made within the same person: how their own glucose behaved after one kind of snack compared with another.

Bread or buns went with the largest extra rise, about 31 units more than other snacks, roughly half the average response on top. Deep-fried foods added about 20, sweets about 15 and sugary drinks about 12. Timing mattered too: the same person's glucose rose more after an afternoon snack (about 9 units) or an early-evening one (about 11) than after a morning one. Movement worked the other way. Each hour of moderate to vigorous activity in the two hours after a snack went with about 28 units less, so on the model's straight-line reading, 15 minutes of brisk walking would take off about 7.

There are limits worth knowing. This is an observational study, so it shows patterns rather than proof that bread itself, rather than what came with it, caused the rise. Snacks were self-reported in broad categories, not weighed, so portion size is unknown, and 'bread or buns' covers anything from plain toast to sweet, filled buns. Everyone was free of diabetes, so the rises were the kind a healthy body handles; whether trimming them protects against diabetes later isn't something this study can show. We could only read the paper's summary, so details such as how snacks were defined are taken from it alone. Still, the practical picture is simple and fits earlier work: what a snack is made of, when you have it, and whether you sit still afterwards all shape what it does to your blood sugar, and a starchy snack isn't automatically gentler than a sweet one.