A 15-minute walk after each meal could prevent older people developing type-2 diabetes, a study has found.
The post-meal walks control blood sugar as well as one long walk, research by George Washington University suggested.
Elevated blood sugar after meals could increase the risk of type-2 diabetes, so resting after eating "is the worst thing you can do", the study said.
Diabetes UK said there were "small differences" between exercise routines - but any activity was beneficial.
The US study was the first to test short bouts of exercise in the "risky period" following meals, when blood sugar can rise rapidly, lead author Loretta DiPietro said.
She said high blood sugar after meals was a key risk factor in the progression from impaired glucose tolerance - what the study called "pre-diabetes" - to type-2 diabetes and cardiovascular disease.
The study found three 15-minute walks were as effective at reducing blood sugar over a 24-hour period as one 45-minute walk of the same "easy-to-moderate" pace.
But walking after food was "significantly more effective" at "blunting the potentially damaging elevations in post-meal blood sugar commonly observed in older people".
Older people may be "particularly susceptible" to poor blood sugar control after meals due to insulin resistance in the muscles and slow or low insulin secretion from the pancreas, the researchers said.
They found the best time to walk was after the evening meal, which is often the largest of the day and therefore causes the greatest rise in blood sugar.
More research needed
This increase often lasted "well into the night and early morning", the study found, but it was "curbed significantly" as soon as people started to walk.
Researchers studied 10 people aged 60 and over who were at risk of developing type-2 diabetes due to higher-than-normal levels of fasting blood sugar and insufficient physical activity.
Dr DiPietro said the findings could lead to an "inexpensive strategy" for preventing type-2 diabetes, but said the results must be confirmed by larger trials.
Weight loss and exercise are widely accepted as key ways to prevent type-2 diabetes, which occurs when the body does not produce enough insulin to function properly, or the body's cells do not react to insulin.
Diabetes UK estimates there are up to seven million UK people at "high risk" of developing type-2 diabetes.
Dr Matthew Hobbs, the charity's head of research, said the study reinforced the message that exercise was "extremely important" to reduce the risk.
Talking about the comparison between one 45-minute walk and three 15-minute walks after meals, he added: "Although there were some small differences, the important take-home message is that doing any physical activity, even at a low intensity, is good for you."