Women who choose plain water over sweet fizzy drinks or fruit juice, have a lower risk of developing diabetes.
Replacing sweet drinks with water could help stave off the metabolic disorder, according to researchers at the Harvard School of Public Health.
But adding water to the sugary beverages a person consumes throughout the day won't make a difference, they said.
Study: Women who choose plain water over sweet fizzy drinks or fruit juice, have a lower risk of developing diabetes
The results are based on the drinking habits of 83,000 women followed for more than a decade.
Lead researcher Dr Frank Hu said it is well established that sugary beverages are bad for diabetes risk.
People have recommended drinking plain water instead of sugar-sweetened beverages, he said, 'and the question is whether this kind of substitution has any impact on diabetes'.
Dr Hu and his team collected data from the massive Nurses Health Study, which tracked the health and lifestyle of tens of thousands of women across the U.S.
The study included 82,902 women who answered questions about their diet and health over a 12-year span.
Over time, about 2,700 of them developed diabetes.
The amount of water women drank did not seem to influence their diabetes risk - those who drank more than six cups a day had the same risk as women who drank less than one cup a day.
However, sugar-sweetened drinks and fruit juice were tied to a higher risk of diabetes - about 10 per cent higher for each cup consumed each day.
The research team estimated that if women replaced one cup of fizzy drink or fruit juice with one cup of plain water, their diabetes risk would fall by 7 or 8 per cent.
'The reality is fruit juices contain the same amount of calories and sugar as soft drinks'
While it is not a huge reduction in the risk, 'because diabetes is so prevalent in our society, even 7 or 8 per cent reduction in diabetes risk is quite substantial in terms of the population,' Dr Hu said.
About 10 per cent of women, or 12.6million, have diabetes in the U.S.
A 7 per cent reduction would mean that instead of ten out of every 100 women having diabetes, the number would be closer to nine out of every 100.
Dr Hu's study, published in the American Journal of Clinical Nutrition, also found that unsweetened coffee or tea might be a good alternative to sugary beverages.
The researchers estimated that replacing one cup of a carbonated drink or fruit juice with one cup of coffee or tea could reduce the risk of developing diabetes by 12 to 17 per cent.
Dr Hu said the study is important in pointing out that fruit juice is not an optimal substitute for soda or other sugar-sweetened drinks.
He said: 'The reality is those juices contain the same amount of calories and sugar as soft drinks.'
The bottom line, he said, is that plain water is one of the best calorie-free choices for drinks, and 'if the water is too plain, you can add a squeeze of lemon or lime'.
Dr Barry Popkin, a professor at the University of North Carolina School of Public Health who was not involved in the study, said: 'It is essentially not that water helps, except with hydration, but that the others hurt.'
Read more: http://www.dailymail.co.uk/health/article-2153137/Drinking-plain-water-instead-fizzy-drinks-fruit-juice-lowers-risk-women-developing-diabetes.html#ixzz1wZg5E4zU